Microbial diversity in biofilms from corroding heating systems

Kjellerup, BV; Thomsen, TR; Nielsen, JL; Højris, Bo; Frølund, B.; Nielsen, Per Halkjær

doi:10.1080/08927010500070992

Cited by 23 publications

(28 citation statements)

References 55 publications

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“…In order to disrupt clusters of cells, 1-ml samples of culture were placed in a sterile 1.5-ml microcentrifuge tube and centrifuged for 10 min at 16,000 ϫ g. A 900-l aliquot of the supernatant was discarded, the pellet was resuspended in the remaining 100 l, and then the sample was exposed to mild sonication for 20 min (twice for a total of 40 min) in a Fisher Scientific FS20 sonicating water bath (Fisher Scientific Inc.). Staining of cells with 4Ј,6Ј-diamidino-2-phenylindole (DAPI) was done as previously described (17).…”

Section: Methodsmentioning

confidence: 99%

Dehalorespiration with Polychlorinated Biphenyls by an Anaerobic Ultramicrobacterium

May

Miller

Kjellerup

et al. 2008

Appl Environ Microbiol

136

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Anaerobic microbial dechlorination is an important step in the detoxification and elimination of polychlorinated biphenyls (PCBs), but a microorganism capable of coupling its growth to PCB dechlorination has not been isolated. Here we describe the isolation from sediment of an ultramicrobacterium, strain DF-1, which is capable of dechlorinating PCBs containing double-flanked chlorines added as single congeners or as Aroclor 1260 in contaminated soil. The isolate requires Desulfovibrio spp. in coculture or cell extract for growth on hydrogen and PCB in mineral medium. This is the first microorganism in pure culture demonstrated to grow by dehalorespiration with PCBs and the first isolate shown to dechlorinate weathered commercial mixtures of PCBs in historically contaminated sediments. The ability of this isolate to grow on PCBs in contaminated sediments represents a significant breakthrough for the development of in situ treatment strategies for this class of persistent organic pollutants.Polychlorinated biphenyls (PCBs) were manufactured between 1930 and 1978, and their widespread use in high-temperature electrical coolants, hydraulic fluids, paints, carbonless paper, and as dedusting agents has resulted in their global distribution in even the most remote regions of the planet and throughout the food chain. The 2005 Priority List of Hazardous Substances (http: //www.atsdr.cdc.gov/cercla/) published by the U.S. Agency for Toxic Substances and Disease Registry ranks PCBs fifth out of 275 substances. Ranking on this list is a combined metric based on the compound's prevalence at facilities within the United States, known or suspected toxicity, and potential for human exposure. With the discovery of Desulfomonile tiedjei strain DCB1 (24) in 1984, the door was opened for the study of bacteria that can reductively dechlorinate halogenated organic compounds that were manufactured for a wide range of applications throughout the 20th century. Subsequently, it was discovered that such bacteria can couple their growth to reductive dehalogenation in a process referred to as dehalorespiration (15) or halorespiration (15,22). There has been an explosion of discoveries in this field, resulting in the identification of dozens of different species and strains that are capable of dechlorinating compounds ranging from chlorinated ethenes (19) to dioxins (5). Most of the bacteria that reductively dechlorinate toxic halogenated industrial pollutants have turned out to be members of the genus Dehalococcoides. Although several of these microorganisms have been successfully developed for commercially viable bioremediation of soils contaminated with chlorinated solvents, a proven effective treatment for in situ treatment of PCBs does not currently exist. As a result, the only accepted treatments for PCBs are remedial technologies such as dredging and capping, which are expensive, disruptive to the environment, and impractical to implement over large areas and in remote locations.Dehalococcoides ethenogenes strain 195, the first of the...

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Section: Methodsmentioning

confidence: 99%

Dehalorespiration with Polychlorinated Biphenyls by an Anaerobic Ultramicrobacterium

May

Miller

Kjellerup

et al. 2008

Appl Environ Microbiol

136

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“…Interestingly, the isolation of T. thermophilus from heating water systems has been reported [102]. Within this context it is notable that heating water systems harbor obviously rather diverse microbial communities [103], [104].…”

Section: Discussionmentioning

confidence: 99%

The Metagenome-Derived Enzymes LipS and LipT Increase the Diversity of Known Lipases

et al. 2012

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Triacylglycerol lipases (EC 3.1.1.3) catalyze both hydrolysis and synthesis reactions with a broad spectrum of substrates rendering them especially suitable for many biotechnological applications. Most lipases used today originate from mesophilic organisms and are susceptible to thermal denaturation whereas only few possess high thermotolerance. Here, we report on the identification and characterization of two novel thermostable bacterial lipases identified by functional metagenomic screenings. Metagenomic libraries were constructed from enrichment cultures maintained at 65 to 75°C and screened resulting in the identification of initially 10 clones with lipolytic activities. Subsequently, two ORFs were identified encoding lipases, LipS and LipT. Comparative sequence analyses suggested that both enzymes are members of novel lipase families. LipS is a 30.2 kDa protein and revealed a half-life of 48 h at 70°C. The lipT gene encoded for a multimeric enzyme with a half-life of 3 h at 70°C. LipS had an optimum temperature at 70°C and LipT at 75°C. Both enzymes catalyzed hydrolysis of long-chain (C12 and C14) fatty acid esters and additionally hydrolyzed a number of industry-relevant substrates. LipS was highly specific for (R)-ibuprofen-phenyl ester with an enantiomeric excess (ee) of 99%. Furthermore, LipS was able to synthesize 1-propyl laurate and 1-tetradecyl myristate at 70°C with rates similar to those of the lipase CalB from Candida antarctica. LipS represents the first example of a thermostable metagenome-derived lipase with significant synthesis activities. Its X-ray structure was solved with a resolution of 1.99 Å revealing an unusually compact lid structure.

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“…Before the removal of biofilms, coupons were rinsed with filtered (0.2‐μm pore size) DHS water. Biofilm samples used for total cell counts and FISH were removed and fixed on site (Kjellerup et al , 2005). FISH was performed as described previously (Kjellerup et al , 2005); the applied FISH probes (Thermo Hybaid, Ulm, Germany) are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Phylogenetic and functional diversity of bacteria in biofilms from metal surfaces of an alkaline district heating system

Kjeldsen

Kjellerup

Egli

et al. 2007

FEMS Microbiology Ecology

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District heating systems (DHS) are extreme aqueous environments characterized by high temperatures, high pH (9.5-10.0), and low nutrient availability. Culture-independent and culture-dependent techniques showed that DHS may nevertheless harbour geno- and phenotypically diverse bacterial biofilm communities. Approximately 50% of the cells in biofilms growing on mild steel coupons in rotortorque reactors connected to the return line (40 degrees C) of a Danish DHS were detectable by FISH analysis and thus were probably metabolically active. A bacterial 16S rRNA gene clone library generated from the biofilms was dominated by proteobacterial phylotypes (closely related to known aerobic species) and by phylotypes affiliated to the anaerobic class Clostridia. Anoxic enrichment cultures derived from biofilms primarily contained 16S rRNA gene and dsrAB (encoding major subunits of dissimilatory sulfite reductase) phylotypes affiliated to the latter class. Alkalitolerant and neutrophilic anaerobic bacteria were isolated from the DHS, including novel Gram-positive and deltaproteobacterial sulfate-reducers and sulfite-reducers constituting novel Gram-positive lineages. In total, 39 distinct 16S rRNA gene phylotypes representing ten classes were identified. The detection of several alkalitolerant, sulfide-producing, and, thus, potentially biocorrosive species underlines the need to maintain a high water quality in the DHS in order to prevent the proliferation of these species.

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Microbial diversity in biofilms from corroding heating systems

Cited by 23 publications

References 55 publications

Dehalorespiration with Polychlorinated Biphenyls by an Anaerobic Ultramicrobacterium

Dehalorespiration with Polychlorinated Biphenyls by an Anaerobic Ultramicrobacterium

The Metagenome-Derived Enzymes LipS and LipT Increase the Diversity of Known Lipases

Phylogenetic and functional diversity of bacteria in biofilms from metal surfaces of an alkaline district heating system

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