Corynebacterium hylobatis sp. nov. and Corynebacterium lemuris sp. nov., two novel species of the genus Corynebacterium isolated from faeces of primates.

Two Gram-stain positive, aerobic, short-rod-shaped, catalase-positive, oxidase-negative and non-motile strains, designated YIM 101343T and YIM 101645T, were isolated from faeces of Hylobates hoolock and Lemur catta, respectively. The results of 16S rRNA gene analysis indicated that both represented members of the genus Corynebacterium, and they shared a similarity of 98.0 % with each other. Corynebacterium marinum DSM 44953T showed the highest similarity with both strains YIM 101343T (99.0 %) and YIM 101645T (97.3 %). The results of phylogenetic analysis based on 16S rRNA gene indicated that strain YIM 101343T formed a cluster with C. marinum DSM 44953T and Corynebacterium comes 2019T, strain YIM 101645T formed a cluster with Corynebacterium halotolerans YIM 70093T, and the two clusters were neighbours. The genomic size of strain YIM 101343T was 3068751 bp and that of strain YIM 101645T was 3169714 bp. The dDDH, ANI and AAI values among strains YIM 101343T, YIM 101645T and the closely related species indicated that the two isolates represented two different novel species. Both strains contained meso-diaminopimelic acid and short-chain mycolic acids, and the major menaquinones were MK-9(H2) and MK-8(H2). The major polar lipids of the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids (>10 %) of both strains were C16 : 0, summed feature 4 and C18 : 1ω9c, but C17 : 1 ω8c was only present as a major component in YIM 101645T . In addition, phenotypic and some chemotaxonomic characteristics of strains YIM 101343T, YIM 101645T and the closely related species were different. Thus, strains YIM 101343T and YIM 101645T should represent two novel species of the genus Corynebacterium, for which the names Corynebacterium hylobatis sp. nov. and Corynebacterium lemuris sp. nov. are proposed, respectively. The type strains are YIM 101343T (=DSM 45970T=CCTCC AB 2013221T) and YIM 101645T (=BCRC 16963T=CCTCC AB 2013281T=KCTC 39868T).

Streptothiazolidine B, a new cytotoxic alkaloid produced by Streptomyces violaceoruber.

A new cytotoxic alkaloid, named streptothiazolidine B (1), together with three known compounds (2-4), were isolated from Streptomyces violaceoruber. The structure of the undescribed compound was established using 1D and 2D NMR, and HRESIMS. Streptothiazolidine B was isolated and identified as an amide alkaloid with a unique thiazolidine side chain and its absolute configuration was determined by a combination of NOESY experiment and ECD analysis. Streptothiazolidine B exhibited significant cytotoxic activities against two human tumor cell lines, Li-7 and A2780, with IC50 values of 7.8, and 9.1 µM. Meanwhile, compound 4 showed obvious cytotoxic activities against four human tumor cell lines, THP-1, HT29, Li-7 and A2780, with IC50 values ranging from 3.1 to 10.2 µM.

Secondary metabolites from the Actinomadura sp. and their cytotoxic activity.

Actinomadura sp., which is usually found in muddy habitats, produces various secondary metabolites with biological activities. In this study, five new compounds named formosensin A (1), formosensin B (2), oxanthroquinone-3-O-α-d-mannose (8), oxanthromicin A (9), and oxanthromicin B (10) were isolated from the culture of Actinomadura sp. together with five known compounds (3-7). Their structures were elucidated by extensive spectroscopic methods including NMR and MS. In particular, the absolute configurations of compounds 1 and 2 were determined using computational methods. Moreover, compounds 1-2 and 8-10 were screened for cytotoxic activity using a panel of human tumor cell lines. Compound 9 induced significant cytotoxicity in five human tumor cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW480) with IC50 values of 8.7, 17.5, 15.0, 17.8, and 14.6 µM, respectively. These findings suggested that compound 9 could provide therapeutic benefits in the treatment of tumor-related diseases.

Gut microbiota and differential genes-maintained homeostasis is key to maintaining health of individuals with Yang-deficiency constitution.

OBJECTIVE: Yang-deficiency constitution (YADC) is a common unbalanced constitution that predisposes individuals to certain diseases. However, not all people with YADC manifest develop diseases. This calls for delineation of the underlying molecular mechanisms. Previous studies suggested that the gut microbiota and gene differential expression should be considered. METHODS: In the present study, we compared profiles of gut microbiota between four healthy YADC individuals and those of five healthy balanced constitution (BC) counterparts, based on 16S rRNA gene sequence analysis. Furthermore, YADC relevant genes identified by comparing 62 healthy YADC and 58 healthy BC individuals in total to perform intersection analysis, functional clustering and pathway enrichment analyses. RESULTS: The levels of harmful gut microbiota (Prevotellaceae, LDA score > 4.0, P = 0.0141) and beneficial gut microbiota (Ruminococcaceae, LDA score > 4.0, P = 0.0025, Faecalibacterium, LDA score > 4.0, P = 0.0484) were both elevated in healthy YADC individuals. Also, we found that the specific metabolic pathway with 2, 6-Dichloro-p-hydroquinone 1, 2-Dioxygenase (PcpA) as the core in gut microbiota and the glutathione transferase activity has been enriched by YADC relevant genes in healthy YADC individuals were both responsible for the detoxification of halogenated aromatic hydrocarbon substances. CONCLUSIONS: Both beneficial and harmful factors had been detected in healthy YADC individuals, functionally, they may have triggered homeostasis to maintain the health of individuals with YADC. The homeostasis may be maintained by beneficial and harmful factors from gut flora and genes. Future studies are expected to focus on halogenated aromatic hydrocarbons and their detoxification processes.

Pathway and molecular mechanisms for malachite green biodegradation in Exiguobacterium sp. MG2.

Malachite green (MG), N-methylated diaminotriphenylmethane, is one of the most common dyes in textile industry and has also been used as an effective antifungal agent. However, due to its negative impact on the environment and carcinogenic effects to mammalian cells, there is a significant interest in developing microbial agents to degrade this type of recalcitrant molecules. Here, an Exiguobacterium sp. MG2 was isolated from a river in Yunnan Province of China as one of the best malachite green degraders. This strain had a high decolorization capability even at the concentration of 2500 mg/l and maintained its stable activity within the pH range from 5.0 to 9.0. High-pressure liquid chromatography, liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry were employed to detect the catabolic pathway of MG. Six intermediate products were identified and a potential biodegradation pathway was proposed. This pathway involves a series of reactions of N-demethylation, reduction, benzene ring-removal, and oxidation, which eventually converted N-methylated diaminotriphenylmethane into N, N-dimethylaniline that is the key precursor to MG. Furthermore, our molecular biology experiments suggested that both triphenylmethane reductase gene tmr and cytochrome P450 participated in MG degradation, consistent with their roles in the proposed pathway. Collectively, our investigation is the first report on a biodegradation pathway of triphenylmethane dye MG in bacteria.

Decolorizing activity of malachite green and its mechanisms involved in dye biodegradation by Achromobacter xylosoxidans MG1.

An Achromobacter xylosoxidans MG1 strainisolated from the effluent treatment plant of a textile and dyeing factory from Yunnan Province in China was found capable of decolorizing the malachite green dye at a high efficacy. Strain MG1 reduced 86% malachite green at the concentration of 2,000 mg/l within 1 h, representing a greater ability for decolorizing and a higher tolerance of this compound than all previously reported bacteria. Color removal was optimal at pH 6 and 38°C. Further experimental evidences demonstrated that both cytoplasmic and extracellular biodegradation contributed to the decolorization of malachite green. Nested PCR was employed to identify the candidate genes responsible for malachite green decolorization, and we identified a cytoplasmic triphenylmethane reductase gene with 100% amino acid similarity to the corresponding gene in Citrobacter sp. strain. In contrast to our expectation, the addition of metyrapone had little effect on the cytoplasmic biodegradation, suggesting that cytochrome P450 was not involved in the high-performance reduction. The extracellular biodegradation was likely attributable to the secretion of extracellular proteases and some heat-resistant compounds.