Abstract

Los Humeros volcanic complex, located at the eastern end of the Trans Mexican Volcanic Belt, possess superficial thermal manifestations (fumaroles, heat steam-soils and alteration zones), with temperatures between 50 °C and 90 °C. This is the first work to explore the bacterial diversity of a steam soil of Los Humeros geothermal field using a metagenomic 16S RNA gene analysis, and the presence of lipolytic enzymes’ genes after an enrichment culture by a whole-genome shotgun approach. High diversity indexes were found in soil samples, with Firmicutes, Chloroflexi, Proteobacteria, Actinobacteria and Acidobacteria as the most prevalent phyla. Alicyclobacillus was the most prevalent genus at 15 cm and Anoxybacillus at 50 cm depth; anaerobic and obligate thermophilic and hyperthermophilic members were found at 50 cm depth. Firmicutes was favored by the oil-rich medium, and the dominant genera were Geobacillus and Caldibacillus. 165 genes related to lipolytic enzymes were found; carboxilesterases and phospholipases C were the most abundant, and 43% were assigned to uncharacterized lipolytic enzymes. The diversity as well as the high percentage of non-characterized lipolytic enzymes found after soil enrichment in an oil-rich medium suggest the presence of biotechnologically promising organisms and enzymes that deserve to be investigated.

摘要

位于墨西哥横贯火山带东端的洛斯胡梅罗斯火山综合体，具有地表热表现（喷气孔，热蒸汽土壤和蚀变带），温度在50°C至90°C之间。这是一项利用宏基因组16S RNA基因分析探索Los Humeros地热田的蒸汽土壤细菌多样性以及通过全基因组and弹枪富集培养后脂解酶基因的存在的第一项工作。在土壤样品中发现了较高的多样性指数，其中最主要的菌群有Firmicutes，Chloroflexi，Proteobacteria，放线菌和Acidobacteria。脂环芽孢杆菌是15厘米处最普遍的属，而在50厘米深度处是嗜氧杆菌；在50厘米深度处发现厌氧和专性嗜热和超嗜热成员。厚皮类被富含油的培养基所偏爱，优势种为地芽孢杆菌和钙芽孢杆菌。发现了165个与脂肪分解酶有关的基因。羧酸酯酶和磷脂酶C最丰富，其中43％被归类为未表征的脂解酶。在富含油的培养基中土壤富集后发现的多样性以及未表征的脂解酶的百分比很高，表明存在生物技术上有希望的生物和酶，值得研究。