Grant Susan, Sorokin Dimitry Y, Grant William D, Jones Brian E, Heaphy Shaun
Department of Microbiology and Immunology, University of Leicester, University Road, LE1 9HN, Leicester, UK.
Extremophiles. 2004 Oct;8(5):421-9. doi: 10.1007/s00792-004-0402-7. Epub 2004 Jul 28.
Samples of sediments and surrounding soda soils (SS) from the extremely saline and alkaline lakes of the Wadi el Natrun in the Libyan Desert, Egypt, were obtained in October 2000. Anaerobic enrichment cultures were grown from these samples, DNA isolated, and the bacterial diversity assessed by 16S rRNA gene clone analysis. Clones derived from lake sediments (LS) most closely matched Clostridium spp., Natronoincola histidinovorans, Halocella cellulolytica, Bacillus spp., and the Cytophaga-Flexibacter-Bacteroides group. Similar clones were identified in the SS, but Bacillus spp. predominated. Many of the clones were most closely related to organisms already identified in alkaline or saline environments. Two genomic DNA libraries were made from the pooled LS enrichments and a single SS-enrichment sample. A novel cellulase activity was identified and characterized in each. The lake cellulase ORF encoded a protein of 1,118 amino acids; BLASTP analysis showed it was most closely related to an endoglucanase from Xanthomonas campestris. The soil-cellulase ORF encoded a protein of 634 amino acids that was most closely related to an endoglucanase from Fibrobacter succinogenes.
2000年10月，从埃及利比亚沙漠瓦迪纳特伦盐碱度极高的湖泊中采集了沉积物样本以及周围的苏打土壤（SS）样本。利用这些样本进行厌氧富集培养，提取DNA，并通过16S rRNA基因克隆分析评估细菌多样性。来自湖泊沉积物（LS）的克隆与梭菌属、组氨酸嗜钠菌、纤维素分解嗜盐菌、芽孢杆菌属以及噬纤维菌-屈挠杆菌-拟杆菌菌群最为匹配。在苏打土壤样本中也鉴定出了类似的克隆，但芽孢杆菌属占主导。许多克隆与已在碱性或盐性环境中鉴定出的生物最为密切相关。从合并的湖泊沉积物富集培养物和一个苏打土壤富集培养物样本构建了两个基因组DNA文库。在每个文库中都鉴定并表征了一种新的纤维素酶活性。湖泊纤维素酶的开放阅读框编码一种含有1118个氨基酸的蛋白质；BLASTP分析表明，它与野油菜黄单胞菌的一种内切葡聚糖酶关系最为密切。土壤纤维素酶的开放阅读框编码一种含有634个氨基酸的蛋白质，与产琥珀酸丝状杆菌的一种内切葡聚糖酶关系最为密切。
