| Objective To screen salt-tolerant esterase-producing strains from yellow water and analyze their metabolic products. Methods Esterase-producing strains were isolated from yellow water and identified using morphological, physiological, biochemical, and molecular biological methods. Results Nine esterase-producing strains were screened from yellow water, among which CZ-1, CZ-5 and CZ-8 were Paenibacillus dendritiformis, CZ-9 was Paenibacillus cookii, CZ-10, CZ-13 and CZ-15 were Bacillus velezensis, and CZ-3 was Saccharomyces cerevisiae. P5-5 is Pichia manshurica. All the 9 strains had good salt-alkali tolerance, and could grow at pH 2.0-11.0, and the salt tolerance was as high as 120 g/L. Experiments showed that when using caproic acid as the substrate, the esterifying enzyme activities of strains CZ-1, CZ-3, CZ-5, CZ-8, CZ-9, CZ-13, CZ-15 and P5-5 were 69.93, 70.62, 6.01, 67.65, 35.31, 48.51, 69.24 and 71.45 U/mL respectively, and strain CZ-10 had no esterifying enzyme activity. GC-MS analysis showed that 12 volatile components of alcohols, 7 volatile components of aldehydes, 1 volatile component of ethers, 3 volatile components of amines, 11 volatile components of ketones, 9 volatile components of esters, 3 volatile components of acids and 22 other volatile components were detected in the fermentation broth. Conclusion Nine esterifying enzyme-producing strains were screened from yellow water, all of which had good salt and alkali tolerance and esterifying enzyme activity. P5-5 had the highest esterifying enzyme activity and the most types of volatile components, which provided a theoretical basis for the subsequent treatment and application of yellow water. |
