Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology Rapid City, SD, USA.
Front Microbiol. 2013 Feb 15;4:18. doi: 10.3389/fmicb.2013.00018. eCollection 2013.
Eight fermentative bacterial strains were isolated from mixed enrichment cultures of a composite soil sample collected at 1.34 km depth from the former Homestake gold mine in Lead, SD, USA. Phylogenetic analysis of their 16S rRNA gene sequences revealed that these isolates were affiliated with the phylum Firmicutes belonging to genera Bacillus and Clostridium. Batch fermentation studies demonstrated that isolates had the ability to ferment glucose, xylose, or glycerol to industrially valuable products such as ethanol and 1,3-propanediol (PDO). Ethanol was detected as the major fermentation end product in glucose-fermenting cultures at pH 10 with yields of 0.205-0.304 g of ethanol/g of glucose. While a xylose-fermenting strain yielded 0.189 g of ethanol/g of xylose and 0.585 g of acetic acid/g of xylose at the end of fermentation. At pH 7, glycerol-fermenting isolates produced PDO (0.323-0.458 g of PDO/g of glycerol) and ethanol (0.284-0.350 g of ethanol/g of glycerol) as major end products while acetic acid and succinic acid were identified as minor by-products in fermentation broths. These results suggest that the deep biosphere of the former Homestake gold mine harbors bacterial strains which could be used in bio-based production of ethanol and PDO.
从美国南达科他州 Lead 的前 Homestake 金矿 1.34 公里深处采集的混合富集培养物中分离出了 8 株发酵细菌菌株。它们的 16S rRNA 基因序列的系统发育分析表明，这些分离物属于厚壁菌门，属于芽孢杆菌属和梭菌属。批式发酵研究表明，这些分离物能够将葡萄糖、木糖或甘油发酵为工业上有价值的产品，如乙醇和 1,3-丙二醇（PDO）。在 pH 值为 10 的葡萄糖发酵培养物中，检测到乙醇作为主要发酵终产物，其产率为 0.205-0.304 g 乙醇/g 葡萄糖。而在发酵结束时，一株木糖发酵菌株产生了 0.189 g 乙醇/g 木糖和 0.585 g 乙酸/g 木糖。在 pH 值为 7 时，甘油发酵分离物产生了 PDO（0.323-0.458 g PDO/g 甘油）和乙醇（0.284-0.350 g 乙醇/g 甘油）作为主要的发酵终产物，而乙酸和琥珀酸则被鉴定为发酵液中的少量副产物。这些结果表明，前 Homestake 金矿的深部生物圈中蕴藏着可用于生物基乙醇和 PDO 生产的细菌菌株。
