A novel, strictly anaerobic, non-motile, non-spore-forming, Gram-negative, short, straight rod with tapered ends, designated YIT 12065T, was isolated from human faeces. Strain YIT 12065T was saccharolytic and negative for catalase, oxidase and urease, hydrolysis of aesculin and gelatin, nitrate reduction and indole production. The end products of glucose fermentation were acetic acid and a small amount of butyric acid. The DNA G+C content was 51.3 mol%. The predominant fatty acids were iso-C15 : 0, C16 : 0 and C14 : 0. Respiratory quinones were not detected. The cell wall contained glutamic acid, serine, alanine and ll-diaminopimelic acid. The whole-cell sugars were ribose, rhamnose, galactose and glucose. Phylogenetic analyses based on 16S rRNA gene sequences using three treeing algorithms revealed that the strain formed a novel family-level lineage within the phylum Firmicutes, class Clostridia, order Clostridiales. Caldicoprobacter oshimai JW/HY-331T was shown to be the closest named relative on the basis of 16S rRNA gene sequence similarity (86.9 %), followed by Tindallia californiensis DSM 14871T (86.3 %) and Clostridium ganghwense JCM 13193T (86.1 %). Similar 16S rRNA gene sequences (98.6–96.7 %) were found amongst faecal uncultured clones of human and dugong (Dugong dugon). They clustered with strain YIT 12065T in a distinct and deep evolutionary lineage of descent in the order Clostridiales. The distinct phylogenetic position supports the proposal of Christensenella gen. nov., with the type species Christensenella minuta sp. nov. (type strain YIT 12065T = DSM 22607T = JCM 16072T). A new family Christensenellaceae fam. nov. is also proposed.
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 12067 T 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 3679 T , 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 succinateproducing bacterium Paraprevotella xylaniphila YIT 11841 T , 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 12067 T . Real-time PCR analysis also revealed that YIT 12067 T -like bacteria were present in 21% of human fecal samples, at an average level of 3.34 ؋ 10 8 cells/g feces. These results indicate that YIT 12067 T -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 12067 T and YIT 12068 suggest that these strains represent a novel species, which we have designated Phascolarctobacterium succinatutens sp. nov.A dvances in culture-independent molecular techniques have allowed a more complete and accurate assessment of the biodiversity of the ecosystem of the human gastrointestinal (GI) tract microbiota (10, 52) and have revealed that most of the phylotypes detected are uncultured (42). For a better understanding of the physiology of the human GI tract microbiota, it is important to isolate, cultivate, and characterize the intestinal microorganisms. Such undertakings provide information on the ecology and physiology of the GI tract microbiota that cannot be acquired from gene sequence information alone. For example, a study that used an isolated strain in the gnotobiotic mouse model revealed that one of the bacteria most frequently detected from human feces, Bacteroides thetaiotaomicron, modulates the expression of host genes involved in nutrient absorption, mucosal barrier fortification, xenobiotic metabolism, angiogenesis, and postnatal intestinal maturation (19). Therefore, cultivation of previously uncultured bacteria will also contribute to a more comprehensive understanding of the human GI tract microbiota through not only the phenotypic characterization of these species but also the sequencing of their whole genomes as a reference for metagenomic studies (53)...
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 17-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 17-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 17-estradiol/liter to 1/100 of the specific activity level after 24 h. It is thus suggested that these strains degrade 17-estradiol into substances without estrogenic activity.Natural estrogens, including 17-estradiol (E2), estrone (E1), and estriol (E3), are excreted in the urine of humans and cattle, most of which flows into wastewater treatment plants. As some natural estrogens are discharged into environments without processing, it is estimated that estrogen discharge is increasing in urban areas (14,15,17). Feminization of a male organism has been noted in rivers and lakes into which sewage is discharged from wastewater treatment plants, and loss of ecological balance is causing concern (7,20,21,29). Since the use of low-dosage oral contraceptive pills was approved by the Central Pharmaceutical Affairs Council in Japan in 1999, environmental loading of ethinyl estradiol (EE2), a synthetic estrogen, is expected to increase (27; T. Yoshimoto, S. Murakami, K. Hamasato, H. Omura, Y. Goda, A. Kobayashi, and S. Fujimoto, Abstr. 4th Annu. Meet. Jpn. Soc. Endocr. Disrupt. Res., p. 155, 2001).Between 1998 and 2000, the Ministry of Land, Infrastructure and Transport conducted a 3-year nationwide survey of 25 endocrine disruptors at 47 wastewater treatment plants in 13 districts of Japan (Tokyo, Sapporo, Sendai, Ibaraki, Saitama, Kawasaki, Yokohama, Nagoya, Shiga, Kyoto, Osaka, Kobe, and Fukuoka). E2, E1, and EE2 concentrations were measured in wastewater and treated wastewater flowing into wastewater treatment plants. EE2 was not detected in any sample in the treatment plants, but E1 and E2 were detected in all plants.The measurement values of E2 and E1 in wastewater influent and treated wastewater were 0.0091 to 0.094 g/liter (125 samples), Ͻ0.0002 (not detected) to 0.066 g/liter (146 samples), 0.015 to 0.077 g/liter (23 samples), and Ͻ0.0005 (not detected) to 0.063 g/liter (24 samples), respectively. The concentrations of E2 were analyzed by an enzyme...
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