School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan.
J Biosci Bioeng. 2011 Mar;111(3):272-8. doi: 10.1016/j.jbiosc.2010.11.015. Epub 2010 Dec 24.
A thermophilic microorganism, SBS-4S, was isolated from a hot spring located in Gilgit, Northern Areas of Pakistan. It was found to be an aerobic, gram-positive, rod-shaped, thermophilic bacterium that grew on various sugars, carboxylic acids and hydrocarbons at temperatures between 45°C and 75°C. Complete 16S rRNA gene sequence of the microorganism exhibited homology to various species of genus Geobacillus. A highest homology of 99.8% was found with Geobacillus kaustophilus. A partial (0.7 kbp) chaperonin gene sequence also showed a highest homology of 99.4% to that of G. kaustophilus whereas biochemical characteristics of the microorganism were similar to Geobacillus uzenensis. Based on biochemical characterization, 16S rRNA and chaperonin gene sequences, we identified SBS-4S as a strain of genus Geobacillus. Strain SBS-4S produced several extracellular enzymes including amylase, protease and lipase. The lipase encoding gene was cloned, expressed in Escherichia coli and the gene product was characterized. The recombinant lipase was optimally active at 60°C with stability at wide pH range (6-12). The enzyme activity was enhanced remarkably in the presence of Ca(+2). The K(m) and the V(max) for the hydrolysis of p-nitrophenyl acetate were 3.8mM and 2273 μmol min(-1)mg(-1), respectively. The ability of the recombinant enzyme to be stable at a wide pH range makes it a potential candidate for use in industry.
从巴基斯坦北部吉尔吉特的一处温泉中分离到一株嗜热微生物 SBS-4S。它是一种需氧、革兰氏阳性、杆状、嗜热细菌，能够在 45°C 到 75°C 之间的各种糖、羧酸和碳氢化合物上生长。该微生物的完整 16S rRNA 基因序列与各种芽孢杆菌属的物种具有同源性。与 Geobacillus kaustophilus 的同源性最高，为 99.8%。部分（0.7 kbp）伴侣蛋白基因序列与 G. kaustophilus 的同源性也最高，为 99.4%，而该微生物的生化特性与 Geobacillus uzenensis 相似。基于生化特性、16S rRNA 和伴侣蛋白基因序列，我们鉴定 SBS-4S 为芽孢杆菌属的一个菌株。菌株 SBS-4S 产生多种胞外酶，包括淀粉酶、蛋白酶和脂肪酶。克隆了脂肪酶编码基因，在大肠杆菌中表达，并对基因产物进行了表征。重组脂肪酶在 60°C 时具有最佳活性，在较宽的 pH 范围（6-12）下具有稳定性。在 Ca(+2)存在下，酶活性显著增强。水解对硝基苯乙酸的 K(m)和 V(max)分别为 3.8mM 和 2273 μmol min(-1)mg(-1)。该重组酶在较宽 pH 范围内稳定的能力使其成为工业应用的潜在候选者。
