Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
BMC Microbiol. 2010 Nov 23;10:298. doi: 10.1186/1471-2180-10-298.
Bacteria may compete with yeast for nutrients during bioethanol production process, potentially causing economic losses. This is the first study aiming at the quantification and identification of Lactic Acid Bacteria (LAB) present in the bioethanol industrial processes in different distilleries of Brazil.
A total of 489 LAB isolates were obtained from four distilleries in 2007 and 2008. The abundance of LAB in the fermentation tanks varied between 6.0 × 105 and 8.9 × 108 CFUs/mL. Crude sugar cane juice contained 7.4 × 107 to 6.0 × 108 LAB CFUs. Most of the LAB isolates belonged to the genus Lactobacillus according to rRNA operon enzyme restriction profiles. A variety of Lactobacillus species occurred throughout the bioethanol process, but the most frequently found species towards the end of the harvest season were L. fermentum and L. vini. The different rep-PCR patterns indicate the co-occurrence of distinct populations of the species L. fermentum and L. vini, suggesting a great intraspecific diversity. Representative isolates of both species had the ability to grow in medium containing up to 10% ethanol, suggesting selection of ethanol tolerant bacteria throughout the process.
This study served as a first survey of the LAB diversity in the bioethanol process in Brazil. The abundance and diversity of LAB suggest that they have a significant impact in the bioethanol process.
在生物乙醇生产过程中，细菌可能会与酵母争夺营养物质，从而导致经济损失。这是首次针对巴西不同酿酒厂的生物乙醇工业过程中存在的乳酸菌（LAB）进行定量和鉴定的研究。
2007 年和 2008 年，从四个酿酒厂共获得 489 株 LAB 分离株。发酵罐中 LAB 的丰度在 6.0×105 到 8.9×108 CFUs/mL 之间变化。原甘蔗汁中含有 7.4×107 到 6.0×108 LAB CFUs。根据 rRNA 操纵子酶限制图谱，大多数 LAB 分离株属于乳杆菌属。各种乳杆菌属的物种在整个生物乙醇过程中都存在，但在收获季节末期最常发现的物种是发酵乳杆菌和葡萄酒乳杆菌。不同的 rep-PCR 模式表明，发酵乳杆菌和葡萄酒乳杆菌的不同种群同时存在，表明种内存在很大的多样性。这两个种的代表性分离株都有能力在含有高达 10%乙醇的培养基中生长，这表明在整个过程中都选择了耐乙醇的细菌。
本研究首次对巴西生物乙醇工艺中的 LAB 多样性进行了调查。LAB 的丰度和多样性表明它们对生物乙醇工艺有重大影响。
