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  • 1.
    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)
  • 2.
    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.

  • 3.
    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.

  • 4. Hogberg, N.
    et al.
    Land, Carl Johan
    KTH, Superseded Departments, Biotechnology.
    Identification of Serpula lacrymans and other decay fungi in construction timber by sequencing of ribosomal DNA - A practical approach2004In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 58, no 2, p. 199-204Article in journal (Refereed)
    Abstract [en]

    We have approached species identification of wood decay fungi in construction wood by means of sequencing ribosomal DNA. Sequencing of the Internal Transcribed Spacer (ITS), which includes the 5.8S rDNA, is straightforward and provides a basis for species identification. Identification was either by BLAST search on sequences in GenBank or phylogenetic analysis. A number of important wood decay fungi such as Serpula lacrymans, S. himantioides, Antrodia serialis, A. sinuosa, Gloeophyllum sepiarium, Fomitopsis pinicola, Resinicium bicolor and Junghuhnia collabens have been successfully identified from fruitbodies and directly from wood samples. Sequence variants were found within the species sampled including S. himantioides, the close relative of S. lacrymans. But, among 27 samples from fruitbodies and mycelium of S. lacrymans, unexpectedly, no sequence variation was detected.

  • 5.
    Land, Carl Johan
    et al.
    KTH, Superseded Departments, Biotechnology.
    Must, A.
    Hogberg, N.
    Identification of fungi, especially Stachybotrys chartarum from gypsum boards, by means of PCR and sequencing of ribosomal DNA2003In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 12, no 4, p. 227-229Article in journal (Refereed)
    Abstract [en]

    Gypsum boards infested by Stachybotrys chartarum are often found in built-in constructions. A PCR-based analysis method has been developed for S. chartarum using specific primers based on the Tri5 gene. Another method for detecting fungi is by species identification via sequencing of ribosomal DNA. Sequencing of ITS (Internal Transcribed Spacer) and the 5.8s rDNA is straightforward and provides a basis for species identification. The sequences were searched for by means of BLAST (Basic Local Alignment Search Tool) in the GenBank. The PCR technique will be an important step in the future both toward detecting fungal infestations at an early stage because of the ability to detect specifically the infestation without time-consuming cultivation in the laboratory and allowing reliable species identification based on sequences obtained from databases.

  • 6. 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.

  • 7. 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.

  • 8. 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.

  • 9. Råberg, Ulrika
    et al.
    Terziev, Nasko
    Land, Carl Johan
    Early soft rot colonization of Scots sapwood pine in above-ground exposure2009In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 63, no 2, p. 236-240Article in journal (Refereed)
    Abstract [en]

    The early colonization of Scots pine (Pinus sylvestris L) sapwood exposed above ground (staple bed) was studied. Two different types of exposures were used, one in an open field and the other in a shaded field. Decay type and degree of degradation due to soft rot and mass and strength loss of wood were correlated. Fungal species in Scots pine sapwood were identified by sequencing, using the fungal nuclear ribosomal DNA (nrDNA) after 24 months. The most abundant decay type found was soft rot, which also agreed with the mass loss (7-8%). Pine sapwood did not differ significantly between the two sites regarding the average mass loss during the time of exposure. The early colonization of wood by soft rot fungi together with mass loss indicates that this fungal type might be more common in above-ground conditions than recognized earlier.

1 - 9 of 9
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