关键词: 枯草芽孢杆菌, 半抑制浓度, 耐盐水解酶, 世代时间

Abstract: To screen microbial resources for decomposing organic carbon in high-salt organic wastewater, one strain of salt-tolerant enzyme-producing bacterium was isolated and screened from bamboo shoot processing waste by dilution coating method and decolorization circle plate test method. The strain was identified based on morphology, scanning electron microscopy observation, physiological and biochemical characteristics, and 16S rRNA gene sequence analysis. A single-factor control method was used to optimize the growth conditions of the strain. The growth of the strain under salt stress and the activities of hydrolytic enzymes (protease, cellulose, and amylase) were measured. A salt-tolerant and organic carbon decomposing strain of Bacillus stubilis ACP81 was obtained, which was able to grow in NaCl solutions with concentrations ranging from 1% to 19%, with optimal growth at 1% NaCl and 5% NaCl as the semi-inhibitory concentration of the strain. The activity of cellulase, neutral protease, and β-amylase in the culture of the strain was 72.4, 3.2, and 0.3 U·mL^-1 respectively at the semi-inhibitory concentration (5% NaCl). Under salt stress, the cellulase and β-amylase activities of strain ACP81 increased with increasing NaCl salt concentration, while the neutral protease showed an opposite trend and the generation time became gradually longer. The isolated Bacillus subtilis ACP81 reached the salinity tolerance range of moderately salinityloving bacteria and had an advantage of cellulase and β-amylase production in hypertonic environment, which can be used as a candidate strain for biochemical treatment of high-salt organic wastewater.

Key words: Bacillus subtilis, semi-inhibitory concentration, salt-resistant hydrolase, generation time.