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首页> 外文期刊>Cytology and genetics >Screening and Genetic Identification of Acidic and Neutral Protease-Producing Yeasts Strains by 26S rRNA gene Sequencing
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Screening and Genetic Identification of Acidic and Neutral Protease-Producing Yeasts Strains by 26S rRNA gene Sequencing

机译：酸性和中性蛋白酶生产酵母菌株的筛选和遗传鉴定的26S rRNA基因测序。

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Protease enzymes (proteases), particularly those produced by microorganisms, play very important roles in industry, due to their diverse applications. Considering the richness of microbial diversity in nature, a good chance always exists that proteases more suitable, with better properties for commercial application, may be discovered while screening novel microorganisms from local environments. In this study, 94 yeasts were isolated from different natural sources collected from the Abha region, Kingdom of Saudi Arabia, to determine extracellular protease production and activity. Among them, 23 isolates (24.46%) showed protease activity using a casein hydrolysis test. Of these, five isolates (21.74%) were selected and identified as the best protease producers by exhibiting the largest clearance zones around colonies. A 26S rRNA gene D1/D2 domain sequence alignment, comparison, and phylogenetic analysis of our study yeasts to published D1/D2 domain rRNA gene sequences from GenBank, identifies the isolates as Rhodotorula mucilaginosa KKU-M12c, Cryptococcus albidus KKU-M13c, Pichia membranifaciens KKU-M18c, Hanseniaspora uvarum KKU-M19c, and Candida californica KKU-M20c. The influence of varying pH (4.0-9.0) on the yield and activity of the proteases was investigated using 0.5% (w/v) casein as a substrate, to detect optimum pH values for yeast extracellular protease production. Enzyme activity was measured using qualitative and quantitative assays. Results show all of the study yeasts secreting protease enzyme at all tested pH levels, with the exception of pH 9.0. This indicates that none of the five yeasts are alkaline protease producers. Maximum protease activity (187 U/mL) was observed in strain H. uvarum KKU-M19c at pH 6.0 (only), indicating that strain KKU-M19c only produces neutral protease. The other four yeast isolates, R. mucilaginosa KKU-M12c, C. albidus KKU-M13c, P. membranifaciens KKU-M18c, and C. californica KKU-M20c, produced both acidic (at pH 4.0) and neutral (at pH 6.0 and 7.0) proteases. Strain C. californica KKU-M20c was found to be the best acidic and neutral protease producer (138 U/mL at pH 4.0, and 185 U/mL at pH 7.0). This is the first report of the discovery and isolation of local, powerful yeasts producing acidic and neutral protease enzymes from the Abha region, Kingdom of Saudi Arabia.
机译：蛋白酶（蛋白酶），尤其是微生物产生的蛋白酶，由于其用途广泛，在工业中起着非常重要的作用。考虑到自然界中微生物多样性的丰富性，在从当地环境中筛选新型微生物时，总是有机会发现更适合商业用途的更适合的蛋白酶。在这项研究中，从沙特阿拉伯王国阿卜哈地区收集的不同天然来源中分离出94种酵母，以确定细胞外蛋白酶的产生和活性。其中，使用酪蛋白水解试验显示23种分离物（24.46％）具有蛋白酶活性。其中，通过展示菌落周围最大的清除区，选择了五种分离物（21.74％）并确定为最佳蛋白酶生产者。从我们的研究酵母菌到GenBank中已发表的D1 / D2域rRNA基因序列的26S rRNA基因D1 / D2域序列比对，比较和系统进化分析，确定了分离株为Rhodotorula mucilaginosa KKU-M12c，白隐隐球菌KKU-M13c，膜毕赤酵母（Pichia membranifaciens） KKU-M18c，Hanseniaspora uvarum KKU-M19c和加利福尼亚念珠菌KKU-M20c。使用0.5％（w / v）酪蛋白作为底物，研究了pH变化（4.0-9.0）对蛋白酶产量和活性的影响，以检测酵母细胞外蛋白酶生产的最佳pH值。使用定性和定量测定法测量酶活性。结果显示，所有研究的酵母均在所有测试的pH水平下分泌蛋白酶，但pH 9.0除外。这表明五种酵母都不是碱性蛋白酶的产生者。在pH 6.0（仅）的H. uvarum KKU-M19c菌株中观察到最大蛋白酶活性（187 U / mL），这表明KKU-M19c菌株仅产生中性蛋白酶。其他四种酵母分离株R. mucilaginosa KKU-M12c，al。C. albidus KKU-M13c，P. membranifaciens KKU-M18c和C. californica KKU-M20c分别产生酸性（pH 4.0）和中性（pH 6.0和7.0）蛋白酶。发现菌株加州棉菌株KKU-M20c是最好的酸性和中性蛋白酶生产者（在pH 4.0下为138U / mL，在pH 7.0下为185U / mL）。这是从沙特阿拉伯王国阿卜哈地区发现并分离出产生酸性和中性蛋白酶的本地强力酵母的第一份报告。

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