The genus Arthrobacter is a source of many natural products that are critical in the development of new medicines. Here, we isolated a novel carotenoid from Arthrobacter sp. QL17 and characterized its properties. The carotenoid was extracted with methanol, and purified by column chromatography and semi-preparative HPLC. Based on micrOTOF-Q and NMR analyses, the pigment was chemically characterized as 2,2 '-((((1E,3E,5E,7E,9E,11E,13E,15E,17E,19E)-3,7,14,18-tetramethylicosa-1,3,5,7,9,11,13,15,17,19-decaene-1,20-diyl)bis(2,2,4-trimethylcyclohex-3-ene-3,1-diyl)) bis(ethan-2-yl-1-ylidene))bi(propane-1,3-diol), and named arthroxanthin. The biological activities of arthroxanthin were evaluated with DPPH, ABTS and MTT assays. Arthroxanthin exhibited excellent radical scavenging properties, as shown for 2, 20-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-n-(3,2-ethyl-benzothiazole-6-sulfonic acid) ammonium salt (ABTS), respectively, with IC50s of 69.8 and 21.5 mu g/mL. It also showed moderate anticancer activities against HepG2, Hela, MDAB-231, SW480, and MKN-45 with IC50 values of 107.6, 150.4, 143.4, 195.9, and 145.5 mu g/mL, respectively. Therefore, arthroxanthin derived from Arthrobacter sp. QL17 may be a potent antioxidant and anticancer agent for food and pharmaceutical use.

对青海省祁连山永久冻土区天然气水合物DK-2钻孔的11件样品进行分析,通过微生物群落分析来探寻水合物层样品与非水合物层样品的差别。在11件样品中均发现了细菌16S rDNA,未检测到海洋天然气水合物地区常见的古菌16S rDNA、mcrA(Ⅰ,Ⅱ)、pmoA、mmoX和mxaF。分析得到的细菌16S rDNA分属5个门,包括变形杆菌门、放线菌门、拟杆菌门、厚壁菌门和异常球菌-栖热菌门,随着样品深度的增加,细菌多样性有降低的趋势。对非水合物层样品DK2-19和水合物层样品DK2-25进行细菌系统发育树分析,发现这2个样品群落结构相差较大。水合物层样品与非水合物层样品细菌群落对比后发现,水合物层样品中γ-变形杆菌的比例低于非水合物层样品中γ-变形杆菌的比例,而Arthrobacter属多发现于非水合物层的样品中。