Monitoring of Desulfitobacterium frappieri PCP‐1 in pentachlorophenol‐degrading anaerobic soil slurry reactors

Abstract

Anaerobic biodegradation of pentachlorophenol (PCP) was studied in rotative bioreactors containing 200 g of PCP-contaminated soil and 250 ml of liquid medium. Reactors were bioaugmented with cells of Desulfitobacterium frappieri strain PCP-1, a bacterium able to dehalogenate PCP to 3-chlorophenol. Cells of strain PCP-1 were detected by quantitative PCR for at least 21 days in reactors containing 500 mg of PCP per kg of soil but disappeared after 21 days in reactors with 750 mg of PCP per kg of soil. Generally, PCP was completely removed in less than 9 days in soils contaminated with 189 mg of PCP per kg of soil. Sorption of PCP to soil organic matter reduced its toxicity and enhanced the survival of strain PCP-1. In some non-inoculated reactors, the indigenous microorganisms of some soils were also able to degrade PCP. These results suggest that anaerobic dechlorination of PCP in soils by indigenous PCP-degrading bacteria, or after augmentation with D. frappieri PCP-1, should be possible in situ and ex situ when the conditions are favourable for the survival of the degrading microorganisms.

Microbial degradation of chlorinated phenols

“…The main product of the biotransformation was 3-CP. In the sequel study, D. frappieri strain PCP-1 was inoculated into rotating biological contactor reactors (RBC) treating soil slurries of PCP contaminated soil (Lanthier et al 2000). PCP was completely removed in less than 9 d in soils contaminated with 189 mg PCP kg -1 of soil.…”

Biodiversity of Dehalorespiring Bacteria with Special Emphasis on Polychlorinated Biphenyl/Dioxin Dechlorinators

“…At the same time, Desulfitobacterium hafniense was described with the type strain DCB-2 T (=DSM 10664 T ) 30) , which is able to dechlorinate pentachlorophenol and 3-chloro-4-hydroxyphenylacetate but not PCE. Some other strains of Desulfitobacterium hafniense were reported to dechlorinate pentachlorophenol 22,79,122) , 2,4,6-trichlorophenol 24) , 3-chloro-4-hydroxy-phenylacetate 51,52) , and PCE 51,120) . Strain PCP-1 was isolated from a methanogenic consortium and classified originally as a new species of the genus Desulfitobacterium with the name Desulfitobacterium frappieri 22) .…”

Geographic distribution of Desulfitobacterium frappieri PCP-1 and Desulfitobacterium spp. in soils from the province of Quebec, Canada

“…from DNA directly extracted from soil samples, specific PCR signals were detected in several soil slurries, suggesting that indigenous Desulfitobacterium are highly competitive with the indigenous microbiota of these soils. The competetivity of inoculated D. frappieri PCP‐1 with indigenous microbiota of various environments has already been demonstrated in different mixed bacterial communities such as anaerobic soil microcosms [23], rotative soil slurry bioreactors [12], and an upflow anaerobic sludge bed reactor [24], as strain PCP‐1 was still present and active several weeks after inoculation. D. dehalogenans was also detected several days after inoculation in anaerobic soil microcosms [25].…”

“…All soils were sieved and flushed for 5 min with a mixture of H 2 /CO 2 /N 2 at a ratio of 8:1:1 before use. The ITB, MS and TS soils were previously described in detail [12]. Most soils sampled at industrial sites or near wood poles had previously been tested for the presence of some pollutants (Table 1).…”