Community structure and dynamics of anaerobic chlorinated ethene-degrading enrichment cultures.
Published: 2005
Language: eng
Number of pages: 181
Description: The purpose of this research was to characterize a set of anaerobic chlorinated ethene-degrading cultures referred to as KB-1. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequence analysis were used to identify key populations in cultures enriched on each chlorinated ethene. Two Dehalococcoides populations were detected in KB-1. One, designated KB-1/VC, was found in all cultures. The other, designated KB-1/PCE, was absent in highly enriched cultures maintained on vinyl chloride. Novel SYBRRTM Green real-time quantitative PCR methods were developed for thirteen of the populations detected: Acetobacterium, Bacteroides, Dehalococcoides, Geobacter, Spirochaetes, Sporomusa, Sulfurospirillum, Syntrophobacter, Syntrophus, Methanomethylovorans, Methanomicrobiales, Methanosaeta, and Methanosarcina. These quantitative PCR techniques were used on thirty DNA samples from various KB-1 cultures, revealing that  Dehalococcoides spp. were the dominant detectable members of most cultures, followed by Sporomusa, Spirochaetes, and  Methanomethylovorans populations. A Geobacter population was present only in cultures maintained on perchloroethene and trichloroethene, suggesting that this population degraded perchloroethene to cis-1,2-dichloroethene. This hypothesis was supported by a timecourse experiment during which the  Geobacter population grew alongside Dehalococcoides spp. during trichloroethene degradation to cis-1,2-dichloroethene, while complete dechlorination to ethene was associated with Dehalococcoides  growth. Dehalococcoides was also associated with dihaloelimination of 1,2-dichlorethane to ethene. The acetogenic  Sporomusa population grew on methanol as well as H2/CO 2 and may have converted methanol to H2 for Dehalococcoides  spp.Dehalococcoides KB-1/PCE and KB-1/VC had identical 16S rRNA gene sequences to published strains with different substrate ranges. Ribosomal intergenic spacer analysis was unable to resolve differences between  Dehalococcoides populations because Dehalococcoides does not have the usual arrangement of rRNA genes. Gyrase B gene sequence analysis using the novel Dehalococcoides-specific primer sets was also unable to distinguish between organisms with identical 16S rRNA gene sequences.Efforts to isolate a Dehalococcoides population capable of rapid growth on vinyl chloride and H2 yielded a nonmethanogenic, >95% pure Dehalococcoides KB-1/VC culture that grew on all dechlorination steps from trichloroethene to ethene. Amending this culture with methanol resulted in higher dechlorination rates, which may have been attributable to the sudden growth of Sporomusa in these cultures.
Notes: Source: Dissertation Abstracts International, Volume: 66-10, Section: B, page: 5542.

Thesis (Ph.D.)--University of Toronto, 2005.

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