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  • 1.
    Andersson, Sofia
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Characterization of Bacterial Biofilms for Wastewater Treatment2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Research performed at the Division of Environmental Microbiology has over the last years resulted in the isolation of possible bacterial key-organisms with efficient nutrient removal properties (Comamonas denitrificans, Brachymonas denitrificans, Aeromonas hydrophila). Effective use of these organisms for enhanced nutrient removal in wastewater treatment applications requires the strains to be retained, to proliferate and to maintain biological activity within theprocess. This can be achieved by immobilization of the organisms using an appropriate system.Two putative immobilization systems, agar entrapment and biofilm formation, wereassessed. Surface attached biofilm growth provided better results with respect to cell retention,proliferation and microbial activity than immobilization in agar beads. Thus, biofilm physiology was further characterized using simplified systems of single, dual or multi strain bacterial consortia containing the key-organisms as well as other wastewater treatment isolates. Mechanisms for initial adherence, biofilm formation over time, dynamics and characteristics of extracellular polymeric substances (EPS) and exopolysaccharides, nutrient removal activity as well as the effect of bacterial interactions were investigated. The results showed that all theassessed bacterial strains could form single strain biofilm providing that a suitable nutrientsupply was given. Production of EPS was found to be critical for biofilm development and both EPS and polysaccharide residue composition varied with bacterial strain, culture conditions and biofilm age. Denitrification and phosphorus removal activity of the keyorganisms was maintained in biofilm growth. Co-culturing of two or more strains resulted in both synergistic and antagonistic effects on biofilm formation as well as the microbial activitywithin the biofilm. Bacterial interactions also induced the synthesis of new polysaccharideswhich were not produced in pure strain biofilms.The complexity of single and mixed strain biofilm development and the implications of interactions on biofilm performance were underlined in this study. The data presented can be useful for modeling of biofilm systems, serve as a tool for selection of bacterial strain combinations to use for bioaugmentation/bioremediation or provide a base for further experiment design.

  • 2.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Bioaugmentation for enhanced denitrification in a labscale treatment system2006In: Proceedings of the Second IASTED International Conference on Advanced Technology in the Environmental Field / [ed] Ubertini, L, ACTA Press, 2006, p. 63-67Conference paper (Refereed)
    Abstract [en]

    The effect of bioaugmentation was investigated in a predenitrification lab-scale wastewater treatment system. The aim was to investigate the difference between two approaches to bioaugmentation: one in which suspended overnight culture was used as inoculum and another where bacteria immobilized in 1% agar beads were used. Pure cultures of the denitrifying bacteria Comamonas denitrificans ATCC 700936T were used in the experiments. The effect of bioaugmentation on the system was monitored using fluorescent in situ hybridization (FISH) and denitrification activity tests. The bioaugmentation with suspended bacteria showed a rapid initial (4 days) increase in denitrification activity. After 8 days the activity declined to the level of the reference system and cells of C. denitrificans were no longer detectable. Augmentation with agar-embedded bacteria resulted in a small increase in activity and very few bacteria of C. denitrificans could be observed.

  • 3.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Influence of microbial interactions and EPS/polysaccharide composition on nutrient removal activity in biofilms formed by strains found in wastewater treatment systems2011In: Microbiology Research, ISSN 0944-5013, E-ISSN 1618-0623, Vol. 166, no 6, p. 449-457Article in journal (Refereed)
    Abstract [en]

    The study of biofilm function, structure and microbial interactions might help to improve our understanding of biofilm wastewater treatment processes. However, few reports specifically address the influence of interactions within multispecies biofilms on microbial activity and biofilm composition. Thus, the relationship between biofilm formation, denitrification activity, phosphorus removal and the composition of extracellular polymeric substances (EPS), exopolysaccharides and the bacterial community was investigated using biofilms of denitrifying and phosphorus removing strains Comamonas denitrificans 110, Brachymonas denitrificans B79, Aeromonas hydrophila L6 and Acinetobacter calcoaceticus ATCC23055. Denitrification activity within the biofilms generally increased with the amount of biofilm while phosphorus removal depended on bacterial growth rate. Synergistic effects of co-growth on denitrification (B. denitrificans B79 and A. hydrophila L6) and phosphorus removal (C. denitrificans 110 with either A. calcoaceticus or A. hydrophila L6) were observed. B. denitrificans B79 was highly affected by interspecies interactions with respect to biofilm formation, denitrification activity and EPS composition, while C. denitrificans 110 remained largely unaffected. In some of the dual and quadruple strain biofilms new exopolysaccharide monomers were detected which were not present in the pure strain samples.

  • 4.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Biological nutrient removal by individual and mixed strain biofilmsManuscript (Other academic)
  • 5.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Characterization of extracellular polymeric substances from denitrifying organism Comamonas denitrificans2009In: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 82, no 3, p. 535-543Article in journal (Refereed)
    Abstract [en]

    Extracellular polymeric substances (EPS) play an important role in the formation and activity of biofilms in wastewater treatment (WWT). The EPS of the denitrifying biomarker Comamonas denitrificans strain 110, produced in different culture media and growth modes, were characterized. The EPS mainly contained protein (3-37%), nucleic acids (9-50%), and carbohydrates (3-21%). The extracellular DNA was found to be important for initial biofilm formation since biofilm, but not planktonic growth, was inhibited in the presence of DNase. The polysaccharide fraction appeared to consist of at least two distinct polymers, one branched fraction (A) made up of glucose and mannose with a molecular weight around 100 kDa. The other fraction (B) was larger and consisted of ribose, mannose, glucose, rhamnose, arabinose, galactose, and N-acetylglucosamine. Fraction B polysaccharides were mainly found in capsular EPS which was the dominant type in biofilms and agar-grown colonies. Fraction A was abundant in the released EPS, the dominant type in planktonic cultures. Biofilm and agar-grown EPS displayed similar overall properties while planktonic EPS showed clear compositional disparity. This study presents results on the physiology of a key WWT organism, which may be useful in the future development of improved biofilm techniques for WWT purposes.

  • 6.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Rajarao, Gunaratna Kuttuva
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Persistence and competition of denitrifying biofilms subjected to a natural wastewater floraManuscript (Other academic)
  • 7.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Biofilm formation and interactions of bacterial strains found in wastewater treatment systems2008In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 283, no 1, p. 83-90Article in journal (Refereed)
    Abstract [en]

    Biofilm formation and adherence properties of 13 bacterial strains commonly found in wastewater treatment systems were studied in pure and mixed cultures using a crystal violet microtiter plate assay. Four different culture media were used, wastewater, acetate medium, glucose medium and diluted nutrient broth. The medium composition strongly affected biofilm formation. All strains were able to form pure culture biofilms within 24 h in at least one of the tested culture media and three strains were able to form biofilm in all four culture media, namely Acinetobacter calcoaceticus ATCC 23055, Comamonas denitrificans 123 and Pseudomonas aeruginosa MBL 0199. The adherence properties assessed were initial adherence, cell surface hydrophobicity, and production of amyloid fibers and extracellular polymeric substances. The growth of dual-strain biofilms showed that five organisms formed biofilm with all 13 strains while seven formed no or only weak biofilm when cocultured. In dual-strain cultures, strains with different properties were able to complement each other, giving synergistic effects. Strongest biofilm formation was observed when a mixture of all 13 bacteria were grown together. These results on attachment and biofilm formation can serve as a tool for the design of tailored systems for the degradation of municipal and industrial wastewater.

  • 8.
    Andersson, Sofia
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Nilsson, Mirja
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Assessment of carrier materials for biofilm formation and denitrification2008In: Vatten, ISSN 0042-2886, Vol. 64, p. 201-207Article in journal (Refereed)
  • 9.
    Azeem, Muhammad
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Borg-Karlson, Anna Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Antagonistic activity of Bacillus subtilis A18 – A19 against Heterobasidion speciesArticle in journal (Other academic)
  • 10.
    Azeem, Muhammad
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Nagahama, Kazuhiro
    Terenius, Olle
    Dept of genetics microbiology and toxicology, Stockholm University.
    Nordenhem, Henrik
    SLU, Uppsala.
    Nordlander, Göran
    SLU, Uppsala.
    Borg-Karlson, Anna Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chemo- and biodiversity of microbes associated with pine weevil (Hylobius abietis)Manuscript (preprint) (Other academic)
  • 11.
    Azeem, Muhammad
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Nordenhem, Henrik
    SLU, Uppsala.
    Nordlander, Göran
    SLU, Uppsala.
    Borg-Karlson, Anna Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Penicillium expansum Volatiles Reduce Pine Weevil Attraction to Host Plants2013In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 39, no 1, p. 120-128Article in journal (Refereed)
    Abstract [en]

    The pine weevil Hylobius abietis (L.) is a severe pest of conifer seedlings in reforested areas of Europe and Asia. To identify minimally toxic and ecologically sustainable compounds for protecting newly planted seedlings, we evaluated the volatile metabolites produced by microbes isolated from H. abietis feces and frass. Female weevils deposit feces and chew bark at oviposition sites, presumably thus protecting eggs from feeding conspecifics. We hypothesize that microbes present in feces/frass are responsible for producing compounds that deter weevils. Here, we describe the isolation of a fungus from feces and frass of H. abietis and the biological activity of its volatile metabolites. The fungus was identified by morphological and molecular methods as Penicillium expansum Link ex. Thom. It was cultured on sterilized H. abietis frass medium in glass flasks, and volatiles were collected by SPME and analyzed by GC-MS. The major volatiles of the fungus were styrene and 3-methylanisole. The nutrient conditions for maximum production of styrene and 3-methylanisole were examined. Large quantities of styrene were produced when the fungus was cultured on grated pine bark with yeast extract. In a multi-choice arena test, styrene significantly reduced male and female pine weevils' attraction to cut pieces of Scots pine twigs, whereas 3-methylanisole only reduced male weevil attraction to pine twigs. These studies suggest that metabolites produced by microbes may be useful as compounds for controlling insects, and could serve as sustainable alternatives to synthetic insecticides.

  • 12.
    Azeem, Muhammad
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norin, Emil
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Terenius, Olle
    Dept of genetics microbiology and toxicology, Stockholm University.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Nordlander, Göran
    SLU, Uppsala.
    Nordenhem, Henrik
    SLU, Uppsala.
    Borg-Karlson, Anna Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fungal metabolite mask the host plant odor of the pine weevil (Hylobius abietis)Article in journal (Other academic)
  • 13.
    Bodlund, Ida
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Sabarigirisan, K
    Anna University, Chennai.
    Chelliah, R
    Anna University, Chennai.
    Sankaran, K
    Anna University, Chennai.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Screening of Coagulant Proteins from Plant Materials in Southern IndiaManuscript (preprint) (Other academic)
  • 14.
    Chelliah, R
    et al.
    Anna University, Chennai.
    Bodlund, Ida
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Sankaran, K
    Anna University, Chennai.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Antibacterial activity of Mustard and Moringa seed extracts against pathogenic organismsManuscript (preprint) (Other academic)
  • 15.
    Desta, Adey F.
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Dalhammer, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Kittuva, Gunatrana R.
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    A modified culture-based study of bacterial community composition in a tannery wastewater treatment plant2010In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 62, no 11, p. 2543-2549Article in journal (Refereed)
    Abstract [en]

    Though culture-independent methods have been used in preference to traditional isolation techniques for characterization of microbial community of wastewater treatment plants, it is difficult to widely apply this approach in resource-poor countries. The present study aimed to develop a test to identify the culturable portion of bacterial community in a high-strength wastewater. Wastewater samples were collected from nitrification-denitrification and settling tanks of the treatment plant of Elmo Leather AB tannery located in Boras, Sweden. After cultivating on nutrient agar with the optimal dilution (10(-2)), phenotypic and biochemical identification of the bacteria were done with colony morphology, Gram reaction, growth on MacConkey, phenylethanol media, triple sugar Iron agar slants, catalase and oxidase tests. Biochemical grouping of the isolates was done based on their test results for MacConkey, phenylethanol media, triple sugar Iron agar and oxidase test reaction. From the biochemical groups, isolates were randomly selected for API test and 16SrRNA gene sequencing. The isolates from the denitrification, nitrification tank were identified to be Paracoccus denitrificans (67%), Azoarcus spp (3%) and Spingomonas wittichii (1%). From the settling tank, Paracoccus denitrificans (22%), Corynebacterium freneyi (20%) and Bacillus cereus (1%) were identified. The grouping based on biochemical test results as well as the identification based on sequencing has shown coherence except for discrepancies with the API test. The preliminary implications of the grouping based on culture-based characteristics and its potential application for resource-limited environmental microbial studies is discussed.

  • 16. Ghebremichael, K. A.
    et al.
    Gunaratna, K. R.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Single-step ion exchange purification of the coagulant protein from Moringa oleifera seed2006In: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 70, no 5, p. 526-532Article in journal (Refereed)
    Abstract [en]

    The coagulant protein from Moringa oleifera (MO) seed was purified using a single-step batch ion exchange (IEX) method. Adsorption and elution parameters were optimized. Impact of the purification on the reduction of organic and nutrient release to the water was studied. The matrix was equilibrated using ammonium acetate buffer, and the optimum ionic strength of NaCl for elution was 0.6 M. The time for adsorption equilibrium was between 90 and 120 min. Maximum adsorption capacity of the matrix, estimated with the Langmuir model, was 68 mg protein/g adsorbent. The purified protein does not release organic and nutrient loads to the water, which are the main concerns of the crude extract. This work suggests that a readily scalable single-step IEX purification method can be used to produce the coagulant protein and it can be carried out with locally available facilities. This will promote the use of MO in large water treatment plants and other industries.

  • 17. Ghebremichael, K. A.
    et al.
    Gunaratna, K. R.
    Henriksson, H.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    A simple purification and activity assay of the coagulant protein from Moringa oleifera seed2005In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 39, no 11, p. 2338-2344Article in journal (Refereed)
    Abstract [en]

    Use of extracts from Moringa oleifera (MO) is of great interest for low-cost water treatment. This paper discusses water and salt extraction of a coagulant protein from the seed, purification using ion exchange, its chemical characteristics, coagulation and antimicrobial properties. The coagulant from both extracts is a cationic protein with pI greater than 9.6 and molecular mass less than 6.5 kDa. Mass spectrometric analysis of the purified water extract indicated that it contained at least four homologous proteins, based on MS/MS peptide sequence data. The protein is thermoresistant and remained active after 5 h heat treatment at 95 degrees C. The coagulant protein showed both flocculating and antibacterial effects of 1.1-4 log reduction. With samples of high turbidity, the MO extract showed similar coagulation activity as alum. Cecropin A and MO extract were found to have similar flocculation effects for clay and microorganisms. Simple methods for both the purification and assay of MO coagulating proteins are presented, which are necessary for large-scale water treatment applications.

  • 18.
    Larsdotter, Karin
    et al.
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Jansen, Jes La Cour
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Biologically mediated phosphorus precipitation in wastewater treatment with microalgae2007In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 28, no 9, p. 953-960Article in journal (Refereed)
    Abstract [en]

    A lab-scale continuous microalgal culture was grown on sterile-filtered wastewater in order to clarify the phosphorus removing mechanisms in a microalgal treatment step that treats residual phosphorus from a hydroponic wastewater treatment pilot plant. The phosphorus assimilation was dependent on algal biomass production, whereas the chemical precipitation was dependent on phosphorus load, i.e. an increase in average precipitation rate with decreased hydraulic retention time was observed. The chemical precipitation was mainly a result of the increased pH, which was biologically mediated by the photosynthesising algae. The precipitate was composed of a calcium phosphate with magnesium included, magnesium hydroxide and calcite. A significant nitrogen removal was also experienced, which implies that the microalgal wastewater treatment is appropriate both for phosphorus and nitrogen removal.

  • 19.
    Larsdotter, Karin
    et al.
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Jansen, Jes La Cour
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Microalgae as a phosphorus trap after hydroponic wastewater treatmentManuscript (Other academic)
  • 20.
    Leta, Seyoum
    et al.
    KTH, School of Biotechnology (BIO).
    Assefa, F.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Enhancing biological nitrogen removal from tannery effluent by using the efficient Brachymonas denitrificans in pilot plant operations2005In: World Journal of Microbiology & Biotechnology, ISSN 0959-3993, E-ISSN 1573-0972, Vol. 21, no 4, p. 545-552Article in journal (Refereed)
    Abstract [en]

    Laboratory scale and pilot plant reactors were inoculated with an efficient denitrifier, Brachymonas denitrificans (CCUG 45880), in order to evaluate whether a bio-augmentation approach can be used to enhance biological nitrogen removal from tannery effluents. To determine the effectiveness of the introduced strain, denitrifying activity in the activated sludge was monitored by nitrate uptake rate ( NUR) measurement of NO3-N. Fluorescent in situ hybridization ( FISH) technique was used to monitor the growth of the augmented species. The laboratory scale nitrate removal efficiency with the introduced B. denitrificans (3.7 +/- 0.6 mg NO3-N gVSS(-1) h(-1)) was higher than that of the activated sludge without the addition of the bacteria (3.5 +/- 0.7 mg NO3-N gVSS(-1) h(-1)); the NUR in the pilot plant after and before the introduction of the strain was also of the magnitude of 12.0 +/- 1.4 and 10.6 +/- 1.4 mg NO3- N gVSS(-1) day(-1), respectively. In situ hybridization results revealed that the introduced denitrifying bacteria significantly facilitated the development of a dense denitrifying bacterial population in the activated sludge, which enhanced in situ denitrification activity. FISH data indicated that once introduced, B. denitrificans remained abundant throughout the experimental period. The ability to seed a bioreactor with bacterial strain capable of removing target pollutants from tannery effluents in a mixed microbial community suggests that this approach could have commercial applications.

  • 21.
    Marobhe, Nancy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva, Gunaratna R.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Effect of coagulant protein from Vigna and Parkinsonia seeds on bacteria isolated from Ruvu River in Tanzania2008In: World Journal of Microbiology & Biotechnology, ISSN 0959-3993, E-ISSN 1573-0972Article in journal (Other academic)
  • 22.
    Marobhe, Nancy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Kuttuva, Gunaratna R.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Simple and rapid methods for purification and characterization of active coagulants from the seeds of Vigna unguiculata and Parkinsonia aculeata2007In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 28, no 6, p. 671-681Article in journal (Refereed)
    Abstract [en]

    The coagulating properties of aqueous crude extracts and purified proteins of Vigna unguicilata and Parkinsomia aculeata seeds, which are traditional water coagulants in rural areas of Tanzania, were studied. The coagulation activity assays were done using one millilitre (ml) of kaolin water samples. Coagulating proteins were purified in two-step ion exchange chromatography. The properties of coagulant protein were compared with Moringa oleifera. Coagulating components eluted by 0.6 M NaCl in both coagulants are cationic proteins that have the molecular mass of about 6 kDa, which is very similar to that of M. oleifera. The proteins of V. unguiculata and P. aculeata eluted by 0.3 M NaCl also harbour coagulation activity but proteins eluted with 0.6 M NaCl have higher activity. The dosage for coagulation using purified proteins of both coagulants is about 5 to 10 times lower than that of crude seed extracts. The optimum floc settling time of water treated by crude seed extracts and purified proteins ranged between two and two and half hours. Coagulating proteins of both coagulants elated by 0.6 M NaCl are thermoresistant and retained coagulation activity of 87% to 92% after boiling for two hours at 80 degrees C and one hour at 95 degrees C. Thermotolerant proteins of V. unguiculata eluted by 0.6 M NaCl and P. aculeata have wider pH range of 5.5 to 8.5 for coagulation activity than those of M. oleifera proteins. The present investigation reveals the possibility of using purified natural coagulants for water treatment to produce safe drinking water.

  • 23. Norstrom, Anna
    et al.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Lee, Natuschka M.
    The microbial characterization of a hydroponic treatment step for domestic wastewater - towards an expanded view on the plant-microbial hydroecology2008In: Journal of Environmental Engineering and Science, ISSN 1496-2551, E-ISSN 1496-256X, Vol. 7, no 6, p. 635-644Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to explore the microbial composition in the hydroponic step of a pilot plant for treatment of domestic wastewater under temperate climate conditions. The pilot plant was designed for nitrogen removal and operated at constant conditions. The microbial composition was investigated over a period of 6 month,; using fluorescence in situ hybridization (FISH) to identify key microbial groups. Nitrification rate measurements confirmed the presence and activity of aerobic nitrifying populations. The FISH analysis demonstrated that Proteobacteria, followed by Nitrospirae and Planctomycetes, represented the three most abundant bacterial groups. Interestingly, further FISH studies suggested the presence of one other bacterial group associated with ammonium-oxidizing processes: anaerobic ammonium-oxidizing bacteria within the Planctomycetales. This suggests that the nitrogen turnover in hydroponics systems may be attributed to more complex processes than previous models based only on those performed by aerobic ammonium-oxidizing bacteria.

  • 24.
    Okoli, Chuka
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology. KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Rajarao-Kuttuva, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Protein-functionalized magnetic iron oxide nanoparticles: time efficient potential-water treatment2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 10, p. 1194-Article in journal (Refereed)
    Abstract [en]

    Recent advances in nanoscience suggest that the existing issues involving water quality could be resolved or greatly improved using nanomaterials, especially magnetic iron oxide nanoparticles. Magnetic nanoparticles have been synthesized for the development and use, in association with natural coagulant protein for water treatment. The nanoparticles size, morphology, structure, and magnetic properties were characterized by transmission electron microscope, X-ray diffraction, and superconducting quantum interference device magnetometry. Purified Moringa oleifera protein was attached onto microemulsions-prepared magnetic iron oxide nanoparticles (ME-MION) to form stable protein-functionalized magnetic nanoparticles (PMO+ME-MION). The turbidity removal efficiency in both synthetic and surface water samples were investigated and compared with the commonly used synthetic coagulant (alum) as well as PMO. More than 90 % turbidity could be removed from the surface waters within 12 min by magnetic separation of PMO? ME-MION; whereas gravimetrically, 70 % removal in high and low turbid waters can be achieved within 60 min. In contrast, alum requires 180 min to reduce the turbidity of low turbid water sample. These data support the advantage of separation with external magnetic field (magnetophoresis) over gravitational force. Time kinetics studies show a significant enhancement in ME-MION efficiency after binding with PMO implying the availability of large surface of the ME-MION. The coagulated particles (impurities) can be removed from PMO+ME-MIONby washing with mild detergent or cleaning solution. To our knowledge, this is the first report on surface water turbidity removal using protein-functionalized magnetic nanoparticle.

  • 25.
    Okoli, Chuka
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology. KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Mariey, Laurence
    Spectrochemistry, ENSICAEN, France.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification2011In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 86, no 11, p. 1386-1393Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water-in-oil microemulsion systems (ME-MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME-MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME-MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X-ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1-MION and ME 2-MION) obtained have a size range 7-10 nm. The protein and ME-MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT-IR); the presence of three peaks at 2970, 2910 and 2870 cm(-1) respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS-PAGE. CONCLUSION: The ME-MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein.

  • 26.
    Okoli, Chuka
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology. KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Qin, Jian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Dalhammar, Gunnel
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Characterization of Superparamagnetic Iron Oxide Nanoparticles and Its Application in Protein Purification2011In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 11, no 11, p. 10201-10206Article in journal (Refereed)
    Abstract [en]

    The application of surface modified magnetic adsorbent particles in combination with magnetic separation techniques has received considerable awareness in recent years. There is a particular need in protein purification and analysis for specific, functional and generic methods of protein binding on solid supports. Nanoscale superparamagnetic iron oxide particles have been used to purify a natural coagulant protein extracted from Moringa oleiferaseeds. Spectrophotometric analysis of the coagulant protein was performed using synthetic clay solution as substrate. Protein binding with carboxyl and silica surface modified superparamagnetic iron oxide nanoparticles (SPION) were compared with the known carboxyl methyl cellulose (CMC) beads of ∼1 m. SPION modified with carboxyl surface showed higher binding capacity towards the coagulant protein compared to the CMC beads. The high surface area to volume ratio of the carboxyl-coated SPION resulted in high binding capacity and rapid adsorption kinetics of the crude protein extract. The purification and molecular weight of coagulant protein is analyzed by SDS-PAGE. This approach utilizes the most efficient, feasible and economical method of coagulant protein purification and it can also be applicable to other proteins that possess similar properties.

  • 27.
    Okoli, Chuka
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology. KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sanchez-Dominguez, Margarita
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Civera, Concepción
    Solans, Conxita
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Comparison and Functionalization Study of Microemulsion-Prepared Magnetic Iron Oxide Nanoparticles2012In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 22, p. 8479-8485Article in journal (Refereed)
    Abstract [en]

    Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 rim were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization similar to 35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications.

  • 28.
    Pavankumar, Asalapuram Ramachand
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology (closed September 2009).
    Ayyappasamy, S. P.
    Sankaran, K.
    Small RNA fragments in complex culture media cause alterations in protein profiles of three species of bacteria2012In: BioTechniques, ISSN 0736-6205, E-ISSN 1940-9818, Vol. 52, no 3, p. 167-172Article in journal (Refereed)
    Abstract [en]

    Efforts to delineate the basis for variations in protein profiles of different membrane fractions from various bacterial pathogens led to the finding that even the same medium [e.g., Luria Bertani (LB) broth] purchased from different commercial sources generates remarkably dissimilar protein profiles despite similar growth characteristics. Given the pervasive roles small RNAs play in regulating gene expression, we inquired if these source-specific differences due to media arise from disparities in the presence of small RNAs. Indeed, LB media components from two different commercial suppliers contained varying, yet significant, amounts of 10-80 bp small RNAs. Removal of small RNA from LB using RNaseA during media preparation resulted in significant changes in bacterial protein expression profiles. Our studies underscore the fact that seemingly identical growth media can lead to dramatic alterations in protein expression patterns, highlighting the importance of utilizing media free of small RNA during bacteriological studies. Finally, these results raise the intriguing possibility that similar pools of small RNAs in the environment can influence bacterial adaptation.

  • 29.
    Pavankumar, Asalapuram Ramachand
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    kayathri, Rajarathinam
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Murugan, Natarajan Arul
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Qiong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Okoli, Chuka
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Kuttuva Rajarao, Gunaratna
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Dimerization of flocculent protein from Moringa oleifera: experimental evidence and in silico interpretationArticle in journal (Refereed)
    Abstract [en]

    Many proteins exist in dimeric and other oligomeric forms to gain stability and functional advantages. In this study, the dimerization property of a coagulant protein (MO2.1) from Moringa oleifera seeds was addressed through laboratory experiments, protein-protein docking studies and binding free energy calculations. The structure of MO2.1 was predicted by homology modelling, while binding free energy and residues-distance profile analyses provided insight into the energetics and structural factors for dimer formation. Since the coagulation activities of the monomeric and dimeric forms of MO2.1 were comparable, it was concluded that oligomerization does not affect the biological activity of the protein.

  • 30. Raberg, U.
    et al.
    Edlund, M. L.
    Terziev, N.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Testing and evaluation of natural durability of wood in above ground conditions in Europe - an overview2005In: Journal of Wood Science, ISSN 1435-0211, E-ISSN 1611-4663, Vol. 51, no 5, p. 429-440Article, review/survey (Refereed)
    Abstract [en]

    Natural durability of wood is determined by the European standard EN 252 for specimens in ground contact and EN 113 for basidiomycetes in the laboratory, but no test exists for above ground conditions. For above ground conditions, the European prestandard ENV 12037 and EN 330 are used to determine the durability of treated wood. The most important factors for fungal establishment on the surface and within wood are the moisture content, the surrounding temperature, and the relative humidity. Strength tests are the most sensitive for decay detection, but neither strength tests nor identification of fungi responsible for the decay are included in the standards of above ground durability in field tests. To detect decay, visual examination , pick or splinter tests, and mass loss determination are used. Identifying fungi with traditional methods, e.g., growth on solid medium, is time consuming and complicated. Molecular methods like polymerase chain reaction and sequencing do not require mycological skill for identification to species level, and furthermore the methods do not depend on the subjective judgement like most traditional methods, but are based on the objective information of the target organism (e.g., nucleotide sequences). The next generation of standard field tests will probably consider the drawbacks of standard tests today and be rapid and include both quality tests like molecular identification and nondestructive quantitative tests, e.g., acoustic tests. Laboratory tests can be improved by using fungi identified from field trials and by combining different fungi in the same test and thus simulate degradation in practice.

  • 31. Raberg, U.
    et al.
    Hogberg, N. O. S.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Detection and species discrimination using rDNA T-RFLP for identification of wood decay fungi2005In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, no 6, p. 696-702Article in journal (Refereed)
    Abstract [en]

    In the present work PCR technology was used as a tool to detect the early stages of wood decay and was compared with microscopic evaluation. The wood decay fungi Postia placenta and Coniophora puteana were detectable in interior wood samples by terminal restriction fragment length polymorphism (T-RFLP) after 2 weeks of incubation with monocultures, while microscopic detection of hyphae was not possible until after 7 weeks. A potential problem when fungal communities are studied with T-RFLPs of rDNA is that intra-specific variation complicates data analysis. In this work, we show that intra-specific sequence variation in the internal transcribed spacer of the rDNA in Coniophora puteana allows T-RFLP identification of this species. This is due to intra-specific variations in fragment length, in combination with the absence of point mutations in the selected restriction sites.

  • 32. Raberg, Ulrika
    et al.
    Brischke, Christian
    Rapp, Andreas O.
    Hogberg, Nils O. S.
    Land, Carl Johan
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    External and internal fungal flora of pine sapwood (Pinus sylvestris L.) specimens in above-ground field tests at six different sites in south-west Germany2007In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 61, no 1, p. 104-111Article in journal (Refereed)
    Abstract [en]

    The occurrence of fungal species on pine sapwood samples obtained from an above-ground field test study was analysed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing. Samples were taken from eight double-layer set-ups that were exposed to the environment at six different locations in south-west Germany. The occurrence of fungal species was correlated with decay intensity and rot types on one hand, and characteristics of the test sites, such as precipitation, average temperature and height above sea level on the other hand. In total, 62 different fungal species were found based on T-RFLP cloning and sequencing. Of the 39 species that were found four or more times, 30 were ascomycetes, five were basidiomycetes, and four could not be classified. The most common fungus found in this study was Coniochaeta ligniaria ((Grev.) Cooke), a soft rot fungus that occurred in 87 of 152 samples (57%). No single factor at the test sites seemed to be decisive for the abundance of fungal species or decay intensity. Within the first years of this study, soft rot fungi was found more frequently in pine sapwood specimens than basidiomycetes.

  • 33.
    Singh, Lakhvinder
    et al.
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Pavankumar, Asalapuram Ramachandran
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Lakshmanan, Ramnath
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Rajarao, Gunaratna Kuttuva
    KTH, School of Biotechnology (BIO), Environmental Microbiology.
    Effective removal of Cu2+ ions from aqueous medium using alginate as biosorbent2012In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 38, no 1, p. 119-124Article in journal (Refereed)
    Abstract [en]

    Removal of heavy metals present in the environment is always of high importance in order to balance ecology with healthy life forms. Biosorption of Cu2+ ions from simulated aqueous medium were studied using calcium alginate beads. Experiments were designed and performed according to Box-Behnken matrix of response surface methodology. The effects of four vital operating variables on the metal-ion sorption characteristics of calcium alginate beads were studied: alginate dosage, initial copper concentrations, pH and agitation time. A high regression coefficient between the variables and response (R-2 = 0.9974) supported excellent evaluation of experimental data by second order polynomial regression model. Maximum removal of Cu2+ ions from aqueous medium was observed at pH 5.5, alginate dosage 2.5% and initial copper concentration of 275 mg l(-1) with an agitation time of 50 min. Thus, the experimental data obtained has been fitted well with Langmuir and Freundlich isotherm models and also exhibited very high correlation coefficients which confirmed suitability of the model and biosorption process. The study revealed that the alginate beads could be used as an ideal material for the removal of Cu2+ ions about 85.3% from aqueous medium and it would be applicable in the process development to treat industrial effluents.

1 - 33 of 33
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