| 11772624 |
Tiirola MA, Mannisto MK, Puhakka JA, Kulomaa MS: Isolation and characterization of Novosphingobium sp. strain MT1, a dominant polychlorophenol-degrading strain in a groundwater bioremediation system. Appl Environ Microbiol. 2002 Jan;68(1):173-80.
A high-rate fluidized-bed bioreactor has been treating polychlorophenol-contaminated groundwater in southern Finland at 5 to 8 degrees C for over 6 years. We examined the microbial diversity of the bioreactor using three 16S ribosomal DNA (rDNA)-based methods: denaturing gradient gel electrophoresis, length heterogeneity-PCR analysis, and restriction fragment length polymorphism analysis. The molecular study revealed that the process was dependent on a stable bacterial community with low species diversity. The dominant organism, Novosphingobium sp. strain MT1, was isolated and characterized. Novosphingobium sp. strain MT1 degraded the main contaminants of the groundwater, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol, at 8 degrees C. The strain carried a homolog of the pcpB gene, coding for the pentachlorophenol-4-monooxygenase in Sphingobium chlorophenolicum. Spontaneous deletion of the pcpB gene homolog resulted in the loss of degradation ability. Phenotypic dimorphism (planktonic and sessile phenotypes), low growth rate (0.14 to 0.15 h (-1)), and low-copy-number 16S rDNA genes (single copy) were characteristic of strain MT1 and other MT1-like organisms isolated from the bioreactor. |
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