Fumiko Nagai

Degradation of estrogens by Rhodococcus zopfii and Rhodococcus equi isolates from activated sludge in wastewater treatment plants

ABSTRACT We have isolated four strains of Rhodococcus which specifically degrade estrogens by using enrichment culture of activated sludge from wastewater treatment plants. Strain Y 50158, identified as Rhodococcus zopfii, completely and rapidly degraded 100 mg of 17β-estradiol, estrone, estriol, and ethinyl estradiol/liter, as demonstrated by thin-layer chromatography and gas chromatography-mass spectrometry analyses. Strains Y 50155, Y 50156, and Y 50157, identified as Rhodococcus equi, showed degradation activities comparable with that of Y 50158. Using the random amplified polymorphism DNA fingerprinting test, these three strains were confirmed to have been derived from different sources. R. zopfii Y 50158, which showed the highest activity among these four strains, revealed that the strain selectively degraded 17β-estradiol during jar fermentation, even when glucose was used as a readily utilizable carbon source in the culture medium. Measurement of estrogenic activities with human breast cancer-derived MVLN cells showed that these four strains each degraded 100 mg of 17β-estradiol/liter to 1/100 of the specific activity level after 24 h. It is thus suggested that these strains degrade 17β-estradiol into substances without estrogenic activity.

Characterization of Phascolarctobacterium succinatutens sp. nov., an asaccharolytic, succinate-utilizing bacterium isolated from human feces.

ABSTRACT Isolation, cultivation, and characterization of the intestinal microorganisms are important for understanding the comprehensive physiology of the human gastrointestinal (GI) tract microbiota. Here, we isolated two novel bacterial strains, YIT 12067T and YIT 12068, from the feces of healthy human adults. Phylogenetic analysis indicated that they belonged to the same species and were most closely related to Phascolarctobacterium faecium ACM 3679T, with 91.4% to 91.5% 16S rRNA gene sequence similarities, respectively. Substrate availability tests revealed that the isolates used only succinate; they did not ferment any other short-chain fatty acids or carbohydrates tested. When these strains were cocultured with the xylan-utilizing and succinate-producing bacterium Paraprevotella xylaniphila YIT 11841T, in medium supplemented with xylan but not succinate, their cell numbers became 2 to 3 orders of magnitude higher than those of the monoculture; succinate became undetectable, and propionate was formed. Database analysis revealed that over 200 uncultured bacterial clones from the feces of humans and other mammals showed high sequence identity (>98.7%) to YIT 12067T. Real-time PCR analysis also revealed that YIT 12067T-like bacteria were present in 21% of human fecal samples, at an average level of 3.34 × 108 cells/g feces. These results indicate that YIT 12067T-like bacteria are distributed broadly in the GI tract as subdominant members that may adapt to the intestinal environment by specializing to utilize the succinate generated by other bacterial species. The phylogenetic and physiological properties of YIT 12067T and YIT 12068 suggest that these strains represent a novel species, which we have designated Phascolarctobacterium succinatutens sp. nov.

Flavobacterium longum sp. nov. and Flavobacterium urocaniciphilum sp. nov., isolated from a wastewater treatment plant, and emended descriptions of Flavobacterium caeni and Flavobacterium terrigena

Two Gram-staining-negative, strictly aerobic, non-endospore-forming, non-motile, rod-shaped bacteria, designated strains YIT 12745T and YIT 12746T, were isolated from sludge from a wastewater treatment plant. 16S rRNA gene sequence analyses indicated that these strains belonged to the genus Flavobacterium. In these analyses, strains YIT 12745T and YIT 12746T were most closely related to the type strains of Flavobacterium caeni and Flavobacterium terrigena, with 16S rRNA gene sequence similarity values of 94.9% and 96.2%, respectively. For both novel strains, menaquinone (MK-6) was the only respiratory quinone. The major fatty acids of strain YIT 12745T were iso-C15:1 G (14.4%), iso-C16:0 (13.2%), C15:0 (12.9%), iso-C15:0 (12.9%) and iso-C17:0 3-OH (11.5%). Those of strain YIT 12746T were iso-C15:0 (21.5%), iso-C16:0 (13.3%), C15:0 (12.0%) and iso-C15:1 G (11.9%). The genomic DNA G+C contents of strains YIT 12745T and YIT 12746T were 48.7 and 30.9 mol%, respectively. From their differential phenotypic and phylogenetic characteristics, these strains are considered to represent two novel species of the genus Flavobacterium, for which the names Flavobacterium longum sp. nov. (type strain YIT 12745T=JCM 19141T=DSM 27077T) and Flavobacterium urocaniciphilum sp. nov. (type strain YIT 12746T=JCM 19142T=DSM 27078T) are proposed. Emended descriptions of Flavobacterium caeni and Flavobacterium terrigena are also proposed.

CO2-dependent growth of Succinatimonas hippei YIT 12066T isolated from human feces

Succinatimonas  hippei  is a new bacterial species isolated from human feces. Here we report that the growth of S. hippei YIT 12066T depends on CO2 or bicarbonate and the headspace gas produced by microbiota. Genetic defect for carbonic anhydrase in this bacterium suggested a reason for the syntrophic property of CO2 dependency and may suggest an adaptation to its habitat.

Development of the Reverse Passive Latex Agglutination Method for the Detection and Quantification of the Genus Nitrospira in the Wastewater Treatment Process

This report describes a new immunological method for the detection and quantification of Nitrospira populations using the reverse passive latex agglutination (RPLA). The numbers of the genus Nitrospira have been quantified only by molecular biological techniques such as FISH and quantitative PCR to date. Using high-density latex particles and a specific polyclonal antibody, Nitrospira populations in the wastewater treatment process were quantified in the shortest 4 h of incubation. The minimum detectable number of Nitrospira cells was 7.0×105 (log10 5.85) cells/ml. It is thought that the RPLA method can quantify Nitrospira populations more simply, economically, and speedily than molecular biological techniques or the culture method, because this procedure has a simple protocol and does not require the use of specialized equipment, expensive reagents, or technical skill. Therefore it is applicable for use in the everyday control and maintenance of water quality in wastewater treatment facilities where equipment is not sufficient or in the field.