Journal of Microbiology

Journal Article

Bacteroides sedimenti sp. nov., isolated from a chloroethenesdechlorinating consortium enriched from river sediment: Mohamed Ismaeil , Naoko Yoshida , Arata Katayama; J. Microbiol. 2018;56(9):619-627. Published online August 23, 2018; DOI: https://doi.org/10.1007/s12275-018-8187-z

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Abstract: A Gram-negative, anaerobic, non-motile, non-spore-forming bacterial strain, designated YN3PY1T, was isolated from a chloroethene-dechlorinating consortium originally enriched from river sediment. The strain enhanced the dechlorination of cis-dichloroethene to ethene by Dehalococcoides, especially at the early stages of cultivation. Strain YN3PY1T was the first isolate of the genus Bacteroides, obtained from animal- independent environments, and its 16S rRNA gene had the highest sequence similarity (97.1%) with Bacteroides luti JCM 19020T in the ‘Coprosuis’ clade of the genus Bacteroides. Strain YN3PY1T formed a phylogenetic cluster with other phylotypes detected from sediments and paddy soil, and the cluster was affiliated with a linage of so-called free-living Bacteroides detected from animal-independent environments, suggesting specific adaptations to sediment-like environments. The strain showed typical phenotypes of Bacteroides, i.e., polysaccharolytic anaerobe having anteiso-C15:0 as the most abundant fatty acid and MK-11 as one of the major respiratory quinones. Additionally, the strain uniquely transforms glucose to lactate and malate, has MK-12 as another major respiratory quinone, and grows at comparatively low temperatures, i.e. 10–40°C, with an optimum at 28°C. Based on the presented data, strain YN3PY1T (= KCTC 15656T = NBRC 113168T) can be proposed as a novel species of the genus Bacteroides and named as Bacteroides sedimenti sp. nov.

Research Support, Non-U.S. Gov'ts

Molecular Characterization of Polychlorinated Biphenyl-Dechlorinating Populations in Contaminated Sediments: Kyoung-Hee Oh , Ellen B. Ostrofsky , Young-Cheol Cho; J. Microbiol. 2008;46(2):165-173. Published online June 11, 2008; DOI: https://doi.org/10.1007/s12275-007-0214-4

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Abstract: Polychlorinated biphenyl (PCB)-dechlorinating microorganisms were characterized in PCB-contaminated sediments using amplified ribosomal DNA restriction analysis (ARDRA). The sediments were prepared by spiking Aroclor 1248 into PCB-free sediments, and were inoculated with microorganisms eluted from St. Lawrence River sediments. PCB-free sediments inoculated with the same inoculum served as the control. Four restriction fragment length polymorphism (RFLP) groups in the eubacterial and two in the archaeal domain were found exclusively in PCB-spiked sediment clone libraries. Sequence analysis of the four eubacterial clones showed homology to Escherichia coli, Lactosphaera pasteurii, Clostridium thermocellum, and Dehalobacter restrictus. The predominant archaeal sequence in the PCB-spiked sediment clone library was closely related to Methanosarcina barkeri, which appear to support earlier findings that methanogens are involved in PCB dechlorination. When the dot-blot hybridization was performed between the sediment DNA extract and the probes designed with eubacterial RFLP groups, the intensity of two of eubacterial RFLP groups, which showed high sequence homology to C. pascui and D. restrictus, was highly correlated with the number of dechlorinating microorganisms suggesting these two members intend to contribute to PCB dechlorination.

Reductive Dechlorination of Polychlorinated Biphenyls as Affected by Natural Halogenated Aromatic Compounds: Jongseol Kim , Ahmi Lee , Yong-Suk Moon , Jae-Seong So , Sung-Cheol Koh; J. Microbiol. 2006;44(1):23-28.; DOI: https://doi.org/2341 [pii]

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Abstract: We investigated the effects of halogenated aromatic compounds (HACs) including naturally occurring ones (L-thyroxine, 3-chloro-L-tyrosine, 5-chloroindole, 2-chlorophenol, 4-chlorophenol and chlorobenzene) on polychlorinated biphenyl (PCB) dechlorination in sediment cultures. A PCB-dechlorinating enrichment culture of sediment microorganisms from the St. Lawrence River was used as an initial inoculum. When the culture was inoculated into Aroclor 1248 sediments amended with each of the six HACs, the extent of dechlorination was not enhanced by amendment with HACs. The dechlorination patterns in the HAC-amended sediments were nearly identical to that of the HAC-free sediments except the 3-chloro-L-tyrosine-amended ones where no dechlorination activity was observed. When these sediment cultures were transferred into fresh sediments with the same HACs, the dechlorination specificities remained the same as those of the initial inoculations. Thus, in the present study, the substrate range of the highly selected enrichment culture could not be broadened by the HACs. It appears that HACs affect PCB dechlorination mainly through population selection rather than enzyme induction of single population.

Effects of Sulfate Concentration on the Anaerobic Dechlorination of Polychlorinated Biphenyls in Estuarine Sediments: Young-Cheol Cho , Kyoung-Hee Oh; J. Microbiol. 2005;43(2):166-171.; DOI: https://doi.org/2167 [pii]

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Abstract: In order to determine the effects of sulfate concentration on the anaerobic dechlorination of polychlorinated biphenyls, sediments spiked with Aroclor 1242 were made into slurries using media which had various sulfate concentrations ranging from 3 to 23 mM. The time course of dechlorination clearly demonstrated that dechlorination was inhibited at high concentration of sulfate due to less dechlorination of meta-substituted congeners. When the dechlorination patterns were analyzed by the calculation of Euclidean distance, the dechlorination pathway in the 3 mM sulfate samples was found to be different from that observed in the 13 mM samples, although the extent of dechlorination in these two samples was similar. It is possible that the dechlorination in the high sulfate concentration samples is inhibited by the suppression of growth of methanogen, which have been shown to be meta-dechlorinating microorganisms.

Dechlorination of 4-Chlorobenzoate by Pseudomonas sp. DJ-12: Chae, Jong Chan , Kim, Chi Kyung; J. Microbiol. 1997;35(4):290-294.

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Abstract: 4-Chlorobiphenyl-degrading Pseudomonas sp. DJ-12 was able to degrade 4-chlorobenzoate(4CBA), 4-iodobenzoate, and 4-bromobenzoate completely under aerobic conditions. During. the degradation of 4CBA by Pseudomonas sp. DJ-12, chloride ions were released by dechlorination and 4-hydroxybenzoate was produced as an intermediate metabolite. The NotI-KNA fragments of pKC157 containing dechlorination genes hybridized with the gene encoding 4CBA:CoA dehalogenase of Pseudomonas sp. CBS3 which is responsible for the hydrolytic dechlorination of 4CBA. These results imply that Pseudomonas sp. DJ-12 degrades 4CBA to 40hydroxybenzoate via dechlorination as the initial step of its degradativ pathway. The genes responsible for dechlorination of 4CBA were found to be blcated on the chromosomal DNA of Pseudomonas sp. DJ-12.

Effect of Moisture Content on Reductive Dechlorination of Polychlorinated Biphenyls and Population Dynamics of Dechlorinating Microorganisms: O-Seob Kwon , Young Eui Kim , Jong Gyu Park; J. Microbiol. 2001;39(3):195-201.

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Abstract: The effect of moisture content on the reductive dechlorination of polychlorinated biphenyls and population dynamics of dechlorinating microorganisms was investigated in sediments spiked with Aroclor 1248. In sediment slurry with an overlying water layer, dechlorination ensued after a 4-week lag period and reduced the average number of chlorines per biphenyl from 3.91 to 3.15 after 48 weeks. In the sediments of reduced moisture content, however, dechlorination occurred after a lag period of 12 weeks and decreased the average number of chlorines per biphenyl to only 3.62, and the dechlorination rate was also slower. When the population size of dechlorinators, methanogens, and sulfate-reducing bacteria was determined by the most probable number techniques, however, no difference was found between the slurry and the low-moisture sediments, except for methanogens. The growth of dechlorinating populations coincided with the end of the lag period and they then increased by 3 orders of magnitude in two conditions. Specific growth rate of dechlorinators showed little difference between the slurry and the low-moisture sediments; however, growth yield was high in the sediments of reduced moisture content. The reduction of sediment moisture decreased the dechlorination rate and extent of PCBs but did not inhibit the growth of PCB dechlorinators.

Structural Analysis of the fcbABC Gene Cluster Responsible for Hydrolytic Dechlorination of 4-Chlorobenzoate from pJS1 Plasmid of Comamonas sp. P08: Jeong-Soon Lee , Kyoung Lee , Jong-Ok Ka , Jong-Chan Chae , Chi-Kyung Kim; J. Microbiol. 2003;41(2):89-94.

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Abstract: Bacterial strain No. P08 isolated from wastewater at the Cheongju industrial complex was found to be capable of degrading 4-chlorobenzoate under aerobic condition. P08 was identified as Comamonas sp. from its cellular fatty acid composition and 16S rDNA sequence. The fcb genes, responsible for the hydrolytic dechlorination of 4-chlorobenzoate, were cloned from the plasmid pJS1 of Comamonas sp. P08. The fcb gene cluster of comamonas sp. P08 was organized in the order fcbB-fcbA-fcbT1-fcbT2-fcbT3-fcbC. This organization of the fcb genes was very similar to that of the fcb genes carried on the chromosomal DNA of Pseudomonas sp. DJ-12. However, it differed from the fcbA-fcbB-fcbC ordering of Arthrobacter sp. SU. The nucleotide sequences of the fcbABC genes of strain P08 showed 98% and 53% identities to those of Pseudomonas sp. DJ-12 and Arthrobacter sp. SU, respectively. This suggests that the fcb genes might have been derived from Pseudomonas sp. DJ-12 to form plasmid pJS1 in Comamonas sp. P08, or that the fcb genes in strain DJ-12 were transposed from Comamonas sp. P08 plasmid.

Influence of Transition-Metal Cofactors on the Reductive Dechlorination of Polychlorinated Biphenyls (PCBs): O-Seob Kwon , Young-Jin Kim § , Kyung-Je Cho , Jin Ae Lee , Young Eui Kim , In Young Hwang , Jae Hyun Kwon; J. Microbiol. 2003;41(3):189-195.

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Abstract: To enhance the reductive dechlorination of polychlorinated biphenyls (PCBs) under anaerobic conditions, we examined the adjunctive effects of cobalt (Co) and nickel (Ni), which are the central metals of transition-metal cofactors of coenzyme F_430 and vitamin B_12, respectively, on the dechlorination of Aroclor 1248. After 32 weeks of incubation, the average numbers of chlorines per biphenyl in culture vials supplemented with 0.2, 0.5, and 1.0 mM of Co reduced from 3.88 to 3.39, 2.92, and 3.28, respectively. However, the numbers of chlorine after supplementing with Ni decreased from 3.88 to 3.43, regardless of the Ni concentrations. The observed congener distribution patterns of all vials with different conditions were similar to the pattern produced by the dechlorination process of H' after 21 weeks of incubation, and these patterns were unchanged up to week 32, except for vials supplemented with 0.5 and 1.0 mM of Co. In vials containing 0.5 mM of Co, meta-rich congeners, such as 25/ 25-, 24/25-, and 25/23-chlorobiphenyls (CBPs), which were found as accumulated products of dechlorination in other conditions, were further dechlorinated, and 25/2-, 24/2-, and 2/2-CBPs were concomitantly increased after 32 weeks of incubation. In this case, the congener distribution was similar to the dechlorination pattern of process M. From these results, we suggested that the enrichment of cultures with Co might stimulate the growth of specific populations of meta-dechlorinators, and that populations might promote a change in the dechlorination process from H' to M, which is known to be less effective on the dechlorination of the more highly chlorinated congeners of PCBs.

Characteristics of Several Bacterial Isolates Capable of Degrading Chloroaliphatic Compounds via Hydrolytic Dechlorination: Ji-Sook Song , Dong-Hun Lee , Kyoung Lee , Chi-Kyung Kim; J. Microbiol. 2003;41(4):277-283.

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Abstract: Haloaliphatic hydrocarbons have been widely used as solvents and ingredients of pesticides and herbicides. However, when these compounds contaminate the environment, they can be very hazardous to animals and humans because of their potential toxicity and carcinogenicity. Therefore, lots of studies have been made for microbial degradation of those pollutant chemicals. In this study, 11 bacterial strains capable of degrading 1,2-dichloroethane (1,2-DCA), 2-chloropropionic acid (2-CPA), 2,3-dichloropropionic acid (2,3-DCPA), and 2-monochloroacetic acid (2-MCA) by hydrolytic dechlorination under aerobic conditions were isolated from wastewaters and rice paddy soil samples. Their morphological and biochemical characteristics and their degradation capabilities of haloaliphatic hydrocarbons were examined. On the basis of the 16S rDNA sequences, 8 different kinds of microbial species, including Pseudomonas plecoglossicida, Xanthobacter flavus, Ralstonia eutropha, were identified. All of the isolated strains can degrade MCA. In particular, strains UE-2 and UE-15 degraded 1,2-DCA, and strain CA-11 degraded 2,3-DCPA, which are hardly degraded by other strains.

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