Search

Background: Bioprospecting of actinobacteria isolated from Kubuqi desert, China for antibacterial, antifungal and cytotoxic metabolites production and their structure elucidation. Results: A total of 100 actinobacteria strains were selectively isolated from Kubuqi desert, Inner Mongolia, China. The taxonomic characterization revealed Streptomyces as the predominant genus comprising 37 different species, along with the rare actinobacterial genus Lentzea. The methanolic extracts of 60.8% of strains exhibited potent antimicrobial activities against Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Salmonella enterica, Saccharomyces cerevisiae and high to mild in vitro cytotoxicity against PC3 (prostate cancer) and A549 (lung carcinoma) cell lines. The metabolomics analysis by TLC, HPLC-UV/vis, HPLC-MS and NMR showed the presence of compounds with molecular weights ranging from 100 to 1000 Da. The scale-up fermentation of the prioritized anti-Gram-negative strain PU-KB10–4 (Streptomyces griseoviridis), yielded three pure compounds including; griseoviridin (1; 42.0 mgL− 1) with 20 fold increased production as compared to previous reports and its crystal structure as monohydrate form is herein reported for the first time, mitomycin C (2; 0.3 mgL− 1) and a new bacterial metabolite 4-hydroxycinnamide (3; 0.59 mgL− 1). Conclusions: This is the first report of the bioprospecting and exploration of actinobacteria from Kubuqi desert and the metabolite 4-hydroxycinnamide (3) is first time isolated from a bacterial source. This study demonstrated that actinobacteria from Kubuqi desert are a potential source of novel bioactive natural products. Underexplored harsh environments like the Kubuqi desert may harbor a wider diversity of actinobacteria, particularly Streptomyces, which produce unique metabolites and are an intriguing source to develop medicinally valuable natural products. [ABSTRACT FROM AUTHOR]

A novel in vitro 3D micronucleus assay was developed in China using the EpiSkin™ 3D human skin model. This EpiSkin™ Micronucleus Assay showed good predictivity and reproducibility during internal validation and is expected to contribute to in vitro genotoxicity testing as a follow-up for positive results from 2D micronucleus assay. Having developed the assay in one laboratory, further work focused on the transferability and inter-laboratory reproducibility in two additional Chinese authority laboratories (Guangdong Provincial Center for Disease Control and Prevention and Zhejiang Institute for Food and Drug Control). Formal training was provided for both laboratories, which resulted in good transferability based on the results of two positive compounds, such as mitomycin C and vinblastine. Independent experiments were then performed, and inter-laboratory reproducibility was checked using 2-acetylaminofluorene, 5-fluorouracil, 2,4-dichlorophenol, and d -limonene. The dose-responses of the positive control chemical, mitomycin C, were similar to those of the developing laboratory, and all test chemicals were correctly classified by all laboratories. Overall, there was a good transferability as well as intra- and inter-laboratory reproducibility of the EpiSkin™ Micronucleus Assay. This study further confirmed the assay's robustness and provided confidence to enter following validation stages for scientific acceptance. [ABSTRACT FROM AUTHOR]

A whole-cell bacterial bioreporter Acinetobacter baylyi strain ADP1_recA_lux that responds to genotoxins was employed to directly assess the adverse effects of the bioavailable fraction of mitomycin C (MMC), benzo[a]pyrene (BaP), chromium (VI) and lead (II) in amended soils and soil samples from two fragile areas in China without soil pre-treatment. The amended soils containing pollutants with the concentrations as low as 0.4 mg/kg MMC, 0.5 mg/kg BaP, 520 mg/kg Cr (VI) and 2072 mg/kg Pb (II) were found to be toxic. Soil particle-associated pollutants accounted for 86%, 100%, 29%, and 92% of the genotoxicity in the MMC, BaP, Cr (VI), and Pb (II) amended soil, respectively. The soils from contaminated sites were also valid to be genotoxic. The results suggest both free and soil particle-associated pollutants are bioavailable to soil organisms and a solid-phase contact bioreporter assay to soil contamination could provide a rapid screening tool for environmental risk assessment. [ABSTRACT FROM AUTHOR]

An Escherichia coli O157:H7 outbreak in China in 1999 caused 177 deaths due to hemolytic uremic syndrome. Sixteen outbreak associated isolates were found to belong to a new clone, sequence type 96 (ST96), based on multilocus sequence typing of 15 housekeeping genes. Whole genome sequencing of an outbreak isolate, Xuzhou21, showed that the isolate is phylogenetically closely related to the Japan 1996 outbreak isolate Sakai, both of which share the most recent common ancestor with the US outbreak isolate EDL933. The levels of IL-6 and IL-8 of peripheral blood mononuclear cells induced by Xuzhou21 and Sakai were significantly higher than that induced by EDL933. Xuzhou21 also induced a significantly higher level of IL-8 than Sakai while both induced similar levels of IL-6. The expression level of Shiga toxin 2 in Xuzhou21 induced by mitomycin C was 68.6 times of that under non-inducing conditions, twice of that induced in Sakai (32.7 times) and 15 times higher than that induced in EDL933 (4.5 times). Our study shows that ST96 is a novel clone and provided significant new insights into the evolution of virulence of E. coli O157:H7. [ABSTRACT FROM AUTHOR]

Abstract Aim: To assess the safety and efficacy of fornix-based tra­beculectomy with the ‘anchoring’ corneal suture technique in Chinese patients. Methods: A retrospective non-comparative case series of 66 eyes of 63 Chinese patients who underwent fornix-based trabeculectomy combined with intraoperative mitomycin C (MMC) 0.4 mg/mL for 2-5 min were studied. Conjunctival wound closure of all eyes was with the anchoring corneal suture technique using a 9-0 nylon suture to prevent leakage at the corneolimbal interface. The success rate, with or without anti-glaucoma medication, the complication rate and the longevity of the drainage blebs were analyzed. Results: At a mean follow-up period of 447.36 ± 337.98 days, the mean intraocular pressure decreased from 26.83 ± 7.90 mmHg to 17.74 ± 8.74 mmHg (P < 0.001). The mean glaucoma medication decreased from 2.95 ± 0.98 preoperatively to 1.23 ± 1.41 postoperatively (P < 0.001). Thirty-one eyes (47.0%) required no anti-glaucoma medication postoperatively. Twenty eyes (30.3%) had qualified success postoperatively. Eight eyes (12.1%) had early wound leakage that resolved with conservative treatment. Three eyes (4.5%) required surgical repair. One eye (1.5%) had hypotonous maculopathy. No other major complications were encountered. Conclusion: Fornix-based trabeculectomy with adjunctive mitomycin C employing the anchoring corneal suture technique appears to be both safe and effective in Chinese patients. [ABSTRACT FROM AUTHOR]