Isolation and screening of gossypol degrading microorganisms and evaluation of their application in preparation of cottonseed meal fermented feed

YE Ze; JI Bin; PENG Yinan; WANG Zhiye

doi:10.13557/j.cnki.issn1002-2813.2025.10.016

Abstract：The study collected fermented feed samples from Gansu Province and isolate bacteria by acetic acid gossypol as the sole carbon source.Through microscopic observation,16S rDNA sequencing,and physiological and biochemical analysis,a strain of Bacillus subtilis FH-1 was isolated.FH-1 strain can tolerate a pH of 3.0 and 0.4%bovine bile salts.After four hours of cultivation in artificial intestinal fluid,the number of live bacteria increased significantly(P<0.05),and it was sensitive to multiple antibiotics.Gossypol degradation experiments showed that FH-1 degraded 68.28%acetic acid gossypol at 24 hours.Single-factor experiments and orthogonal experiments determined that the optimal conditions for the fermentation of cottonseed meal were a substrate to water ratio of 1.0∶0.9,an inoculation amount of 10%,a fermented temperature of 42℃,and a fermented time of 96 h.Under these conditions,the degradation rate of gossypol was 60.03%.Compared with the raw materials,the content of crude protein and crude fat in the FH-1 fermented diet decreased,the phosphorus content increased,and the content of acetic acid,butyric acid and lactic acid significantly increased(P<0.05).Scanning electron microscopy showed that the plant tissues of cottonseed meal solid-state fermented by the FH-1 strain shrank and collapsed.Microbial flora analysis indicated that compared with the raw materials,the types of opportunistic pathogenic bacteria in the FH-1 strain fermented diet decreased,and the proportion of beneficial microorganisms increased.The study indicates that fermented cottonseed meal with FH-1 strain can reduce the content of free gossypol in the diet,improve the palatability of the diet,promote the proliferation of beneficial microorganisms,and has a good application prospect.