Chen Xiao-Ge, Stabnikova Olena, Tay Joo-Hwa, Wang Jing-Yuan, Tay Stephen Tiong-Lee
Environmental Engineering Research Center, School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore.
Extremophiles. 2004 Dec;8(6):489-98. doi: 10.1007/s00792-004-0412-5. Epub 2004 Aug 21.
A proteolytic thermophilic bacterial strain, designated as strain SF03, was isolated from sewage sludge in Singapore. Strain SF03 is a strictly aerobic, Gram stain-positive, catalase-positive, oxidase-positive, and endospore-forming rod. It grows at temperatures ranging from 35 to 65 degrees C, pH ranging from 6.0 to 9.0, and salinities ranging from 0 to 2.5%. Phylogenetic analyses revealed that strain SF03 was most similar to Saccharococcus thermophilus, Geobacillus caldoxylosilyticus, and G. thermoglucosidasius, with 16S rRNA gene sequence identities of 97.6, 97.5 and 97.2%, respectively. Based on taxonomic and 16S rRNA analyses, strain SF03 was named G. caldoproteolyticus sp. nov. Production of extracellular protease from strain SF03 was observed on a basal peptone medium supplemented with different carbon and nitrogen sources. Protease production was repressed by glucose, lactose, and casamino acids but was enhanced by sucrose and NH4Cl. The cell growth and protease production were significantly improved when strain SF03 was cultivated on a 10% skim-milk culture medium, suggesting that the presence of protein induced the synthesis of protease. The protease produced by strain SF03 remained active over a pH range of 6.0-11.0 and a temperature range of 40-90 degrees C, with an optimal pH of 8.0-9.0 and an optimal temperature of 70-80 degrees C, respectively. The protease was stable over the temperature range of 40-70 degrees C and retained 57 and 38% of its activity at 80 and 90 degrees C, respectively, after 1 h.
从新加坡的污水污泥中分离出一株蛋白水解嗜热细菌菌株，命名为SF03菌株。SF03菌株是严格需氧、革兰氏染色阳性、过氧化氢酶阳性、氧化酶阳性且形成芽孢的杆菌。它在35至65摄氏度、pH值6.0至9.0以及盐度0至2.5%的条件下生长。系统发育分析表明，SF03菌株与嗜热糖球菌、嗜热解木糖地芽孢杆菌和嗜热葡萄糖苷酶地芽孢杆菌最为相似，其16S rRNA基因序列同一性分别为97.6%、97.5%和97.2%。基于分类学和16S rRNA分析，SF03菌株被命名为嗜热解蛋白地芽孢杆菌新种。在添加不同碳源和氮源的基础蛋白胨培养基上观察到SF03菌株产生细胞外蛋白酶。葡萄糖、乳糖和酪蛋白氨基酸会抑制蛋白酶的产生，但蔗糖和氯化铵会增强其产生。当SF03菌株在10%脱脂牛奶培养基上培养时，细胞生长和蛋白酶产生显著改善，这表明蛋白质的存在诱导了蛋白酶的合成。SF03菌株产生的蛋白酶在pH值6.0至11.0和温度40至90摄氏度的范围内保持活性，最佳pH值分别为8.0至9.0，最佳温度为70至80摄氏度。该蛋白酶在40至70摄氏度的温度范围内稳定，在80和90摄氏度下分别保温1小时后，仍保留其活性的57%和38%。
