潜在的水体修复菌Bacillus subtilis H001的筛选及其高密度培养

High-density Culture and Potential Aquatic Remediation Activity of Bacillus subtilis H001

摘要:

在水产养殖规模日益扩大和集约化程度不断提高时，带来了养殖水体富营养化、亚硝酸盐超标、致病微生物等问题，在其中引入益生菌，可起到预防和控制的作用。从10株枯草芽孢杆菌中，筛选出菌株H001具有较高淀粉酶和蛋白酶酶活，分别为36.7 U/mL和35.6 U/mL。当麸皮浸汁为40 g/L，玉米浸汁为15 g/L，豆粕为20 g/L，H001菌落总数（TCN）对数值分别为12.1，12.1和14.0。当玉米浸汁与豆粕粉质量比为2：1时，麸皮浸汁与豆粕粉的质量比为2:1时，H001的TCN对数值都约为15.0。在模拟水体中，当亚硝酸盐含量分别为5.0 mg/L、10.0 mg/L、20.0 mg/L、30.0 mg/L、40.0 mg/L和50.0 mg/L时，菌株H001对其降解率分别为95.0%、95.0%、84.1%、68.6%、48.5%和44.4%。综上所述，具有较高淀粉酶和蛋白酶酶活的枯草芽孢杆菌H001，其培养基经优化后TCN提高到1.6×1015 CFU/mL，优化后培养基组合经济且适合于H001的高密度培养，H001是一种潜在的养殖水体修复菌。

Abstract:

The increase in scale and degree of intensification of aquaculture has led to several environmental issues, such as eutrophication, excessive nitrite content, and presence of pathogenic microorganisms, in the water bodies used for aquaculture. Introduction of probiotics into such water bodies can help prevent and control these critical issues. Bacillus subtilis strain H001 was selected from among ten screened strains as it showed higher amylase (36.7 U/mL) and protease (35.6 U/mL) activities. The medium components were varied in order to optimize the medium for H001 growth, and the effect was investigated in terms of the logarithm of total colony number [log(TCN)]. Highest log(TCN) values for H001 were obtained for 40 g/L bran-based broth, 15g/L corn-based broth, and 20 g/L soybean meal, at 12.1, 12.1, and 14.0, respectively. The log(TCN) was approximately 15 when the mass ratio of corn-based broth (or bran-based broth) to soybean meal was 2:1. The rate of nitrite degradation by H001 in the simulated water body was 94.5%, 95.0%, 84.1%, 68.6%, 48.5%, and 44.4% when the initial nitrite concentration was 5.0, 10.0, 20.0, 30.0, 40.0, and 50.0 mg/L, respectively. In summary, the TCN of Bacillus subtilis H001 with higher amylase and protease activities increased to 1.6 × 1015 CFU/mL after the medium was optimized. This optimized medium was economical and suitable for high-density culture of H001. Strain H001 is presented as a potential aquatic bioremediation agent for water bodies used in aquaculture.