Copranaerobaculum intestinale gen. nov., sp. nov., a novel anaerobic bacterium isolated from human faeces.

A novel obligate anaerobic organism, designated DONG20-135T, was isolated from human faeces collected in Beijing, PR China. Cells were Gram-stain-negative, rod-shaped, non-motile and non-spore-forming. Growth occurred at 25‒45 °C (optimum, 30‒35 °C), a pH range of 6-9 (optimum, pH 8) and in the presence of 0‒3.5 % (w/v) NaCl (optimum, 0.5‒1.5 %). The major fatty acids were C16 : 0, C18 : 1 ω9c and C10 : 0, the polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, four glycolipids, six aminolipids, three aminophospholipids and four unidentified lipids. No respiratory quinones were detected. The cell-wall peptidoglycan of the strain was A1γ type, containing meso-diaminopimelic acid. The 16S rRNA gene sequences shared a lower identity (<92.7 % similarity) with the described species. The phylogenetic tree based on 16S rRNA gene sequences and the protein-concatamer tree showed that strain DONG20-135T formed a distinct lineage within the family Erysipelotrichaceae. The genomic DNA G + C content was 42.2 mol%. Based on the results of phenotypic, chemotaxonomic and genomic analyses, strain DONG20-135T represents a novel genus of the family Erysipelotrichaceae, for which the name Copranaerobaculum intestinale gen. nov., sp. nov. is proposed (=KCTC 15868T=CGMCC 1.17357T).

Short-term high-dose gavage of hydroxychloroquine changes gut microbiota but not the intestinal integrity and immunological responses in mice.

AIMS: Hydroxychloroquine (HCQ), a widely used antimalarial drug, is proposed to treat coronavirus disease 2019 (COVID-19). However, no report is currently available regarding the direct effects of HCQ on gut microbiota, which is associated with the outcomes of elderly patients with COVID-19. Here, we first investigated the effects of HCQ on intestinal microecology in mice. MAIN METHODS: Fifteen female C57BL/6J mice were randomly divided into two groups: HCQ group (n = 10) and control group (n = 5). Mice in the HCQ group were administered with HCQ at dose of 100 mg/kg by gavage daily for 14 days. The feces of mice were collected before and on the 7th and 14th days after HCQ challenge, and then analyzed by 16S rRNA amplicon sequencing. At the end of the experiment, the hematology, serum biochemistry and cytokines were determined, respectively. The mRNA expression of tight junction proteins in colonic tissues were also studied by RT-PCR. KEY FINDINGS: HCQ challenge had no effects on the counts of white blood cells, the levels of serum cytokines, and the gene expression of tight junction proteins in colon. HCQ also did not increase the content of serum d-lactate in mice. Notably, HCQ significantly decreased the diversity of gut microbiota, increased the relative abundance of phylum Bacteroidetes whereas decreased that of Firmicutes. SIGNIFICANCE: Short-term high dose HCQ challenge changes gut microbiota but not the intestinal integrity and immunological responses in mice. Special attention should be paid to the effects of HCQ on intestinal microecology in future clinical use.

Correlation of diet, microbiota and metabolite networks in inflammatory bowel disease.

OBJECTIVES: Microbiota dysbiosis in inflammatory bowel disease (IBD) has been widely reported. The gut microbiota connect diet to the metabolism by producing small molecules via diverse metabolic pathways. In this study we aimed to investigate the dietary preferences of IBD patients, and to explore the interactions among gut microbiota composition, dietary components, and metabolites in relation to IBD. METHODS: Dietary preferences of IBD patients (including those with ulcerative colitis [UC] and Crohn's disease [CD]) and health controls were investigated, and their gut microbiota were analyzed using 16S rRNA gene sequencing and metagenomic analyses of fecal and biopsy samples. The metabolite profiles of the samples were then analyzed using gas and liquid chromatography-mass spectrometry analyses. RESULTS: The daily intake of folic acid, niacin, vitamins C and D, calcium, and selenium differed significantly between patients with IBD and healthy controls. A decrease in long-chain (such as arachidic, and oleic acid) and medium-chain fatty acids (sebacic acid and isocaproic acid) as well as bile acid was observed in patients with IBD. Compared with healthy controls, 22 microbial species (including Sulfolobus acidocaldarius, and Clostridium clostridioforme CAG132) in the UC group and 37 microbial species (such as Bacteroides fragilis and Fusobacterium nucleatum) in the CD group were found to be correlated to diet and metabolites. Bacteroides fragilis was enriched in patients with IBD and associated with multi-nutrients, and 21 metabolites including 25-hydroxyvitamin D3 and taurolithocholic acid. CONCLUSIONS: This study provides an interaction network to identify key micronutrients, microbiota components and metabolites that contribute to IBD.

Mitochondrial modulation of apoptosis induced by low-dose radiation in mouse testicular cells.

OBJECTIVE: To investigate whether apoptosis induced by low-dose radiation (LDR) is regulated by mitochondrial pathways in testicular cells. METHODS: Male mice were exposed to whole-body LDR, and changes in mitochondrial function and in expression of apoptotic factors were analyzed in the testicular cells as follows. Total nitric-oxide synthase (T-NOS) and Na+/K+ ATPase activities were biochemically assayed. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) were determined by flow cytometry using fluorescent probes. Levels of mRNAs encoding cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) were quantified by real-time reverse-transcription PCR (RT-PCR). Expression of Cyt c, AIF, caspase-9, and caspase-3 at the protein level was assessed by western blotting and immunohistochemistry. RESULTS: LDR induced an increase in T-NOS activity and ROS levels, and a decrease in Na+/K+ ATPase activity and mitochondrial Δψm, in the testicular cells. The intensity of these effects increased with time after irradiation and with dose. The cells showed remarkable swelling and vacuolization of mitochondria, and displayed a time- and dose-dependent increase in the expression of Cyt c, AIF, procaspase-9, and procaspase-3. Activation of the two procaspases was confirmed by detection of the cleaved caspases. The changes in expression of the four apoptotic factors were mostly limited to spermatogonia and spermatocytes. CONCLUSION: LDR can induce testicular cell apoptosis through mitochondrial signaling pathways.

Cellular fatty acids as chemical markers for differentiation of Acinetobacter baumannii and Acinetobacter calcoaceticus.

OBJECTIVE: Gas chromatography (GC) was used to investigate the cellular fatty acid (CFA) composition of 141 Acinetobacter baumannii and 32 A. calcoaceticus isolates from different locations in China and to find chemical markers to differentiate these two closely related bacteria. METHODS: Whole cell fatty acid methyl esters (FAMEs) were obtained by saponification, methylation, and extraction for GC analysis, followed by a standardized Microbial Identification System (MIS) analysis. RESULTS: All A. baumannii and A. calcoaceticus strains contained some major fatty acids, namely, 18:1 ω9c, 16:0, Sum In Feature 3, 12:0, 17:1ω8c, 3-OH-12:0, 17:0, Sum In Feature 2, 2-OH-12:0, and 18:0 compounds. Although most of the total CFAs are similar between A. baumannii and A. calcoaceticus strains, the ratios of two pairs of CFAs, i.e., Sum In Feature 3/18:1 ω9c versus 16:0/18:1 ω9c and Sum In Feature 3/18:1 ω9c versus unknown 12.484/18:1 ω9c fatty acids, could differentiate these two closely related bacteria. A. baumannii could be easily classified into two subgroups by plotting some ratios such as Sum In Feature 3/16:0 versus 17:0 and Sum In Feature 3/2-OH-12:0 versus 17:0 fatty acids. CONCLUSION: The ratios of some CFAs could be used as chemical markers to distinguish A. baumannii from A. calcoaceticus.