Abstract

Hypersaline environments harbor a rich microbiota, which produces a wide variety of compounds with potential biotechnological applications. This study was aimed at characterization of halophilic bacteria inhabiting the Eshtehard Desert and screening their hydrolytic activity. Soil samples were taken from Eshtehard Desert, and 32 morphologically distinct colonies were obtained. These isolates were screened for their ability to produce hydrolase enzymes. Of 32 halophilic isolates, most (18 isolates) exhibited lipase activity, followed by protease (12 isolates), and amylolytic activity (11 isolates). Ten potential isolates with higher levels of enzyme activity were characterized using phenotypic and genotypic methods. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates belonged to Gammaproteobacteria and Firmicutes. In terms of genera, the isolates belonged to five major genera including Halomonas, Halobacillus, Idiomarina, Oceanobacillus, and Bacillus. The strains belonging to the Firmicutes phylum showed high proteolytic and lipolytic activities. Characterization of the halophilic enzymes showed that in most cases the optimum salt requirement was within the range of 0.5–1 M, optimum temperature between 45–55°C, and their optimum activity was found to occur at pH 8.0 or above. It may be concluded that the diversity of halophilic bacteria in the Eshteharsd Desert can be considered as a potential source of hydrolytic enzymes. To our knowledge, this is the first report on the ability of Idiomarina sp. to produce amylase. The thermostability and alkaliphilic nature of the enzymes obtained in this study make them potentially useful as catalysis under harsh physicochemical conditions encountered in industrial processes.

中文翻译：

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Eshtehard Desert（伊朗）生产水解酶的中度嗜盐细菌

摘要

高盐环境具有丰富的微生物群，可产生具有潜在生物技术应用潜力的多种化合物。这项研究的目的是表征居住在埃斯哈特沙漠中的嗜盐细菌并筛选其水解活性。从埃什特哈德沙漠采集土壤样品，获得了32个形态上不同的菌落。筛选这些分离物产生水解酶的能力。在32个嗜盐分离株中，大多数（18个分离株）表现出脂肪酶活性，其次是蛋白酶（12个分离株）和淀粉分解活性（11个分离株）。使用表型和基因型方法表征了十种具有较高酶活性水平的潜在分离株。基于16S rRNA基因序列的系统发育分析表明，该分离株属于。γ变形杆菌和Firmicutes。在属方面，株为五大属包括盐单胞菌，Halobacillus为，Idiomarina，Oceanobacillus和芽孢杆菌。属于Firmicutes的菌株门具有很高的蛋白水解和脂解活性。嗜盐酶的特性表明，在大多数情况下，最佳盐分需求在0.5-1 M范围内，最佳温度在45-55°C之间，并且发现其最佳活性发生在pH 8.0或更高的条件下。可以得出结论，埃什特哈斯沙漠中嗜盐细菌的多样性可以被认为是水解酶的潜在来源。据我们所知，这是有关碘叶藻能力的第一份报告。产生淀粉酶。在这项研究中获得的酶的热稳定性和碱性使它们在工业过程中遇到的苛刻物理化学条件下作为催化的潜在用途。