Significant Improvement of Straw  Lignocellulose Degradation Rate by Subordination Consortium Composed of Cellulomonas ZJW-6 and Acinetobacter DA-25

Abstract BackgroundThe effective utilization of lignocellulose is essential for achieving circular economy and sustainable agricultural development. The screening of lignocellulose-degrading strains from the environment and artificial establishment of microbial consortia can achieve better degradation effects. In this paper, microbial consortium 625 was established and screened based on high lignocellulose degradation ability but low β-glucosidase activity of Cellulomonas ZJW-6 to complement enzyme activity and enhance lignocellulose degradation by exerting the subordination effect. This research provides an effective strategy for artificially establishing microbial consortia, improving lignocellulose degradation efficiency, and enhancing bioenergy production.ResultsIn order to establish high-efficiency microbial consortia, Cellulomonas ZJW-6 with low β-glucosidase activity was combined in pairs with 14 strains with high β-glucosidase activity according to the enzyme activity complementation principle, from which microbial consortium 625 composed of strains ZJW-6 and DA-25 was screened, which had significantly enhanced lignocellulose degradation rate compared with purely cultured ZJW-6 strain and other 13 combinations. The single factor test showed that consortium 625 had better pH and temperature tolerance. The lignocellulose degradation rate of this consortium was 57.62% after verification test under optimized conditions using response surface method. The induction test showed that the growth of strain DA-25 was inhibited by strain ZJW-6 and its filtrate, while strain DA-25 and its filtrate promoted the growth of strain ZJW-6 and significantly enhanced the activities of key enzymes in the consortium 625 lignocellulose degrading system, among which the β-Glucosidase activity was significantly higher than that in purely cultured ZJW-6 strain. ConclusionMicrobial consortium 625, composed of Cellulomonas ZJW-6 (dominant strain) and Acinetobacter DA-25, with high lignocellulose degradation efficiency, was screened according to the enzyme activity complementation principle. Interestingly, microbial consortium 625 exhibited complementation in enzyme activities of its two strains, improvement in its tolerance to temperature and pH, and the same effect of DA-25 filtrate as strain DA-25. Based on the previous studies on Acinetobacter, we speculate that a certain compound adverse to the growth of strain DA-25 may be produced during lignocellulose degradation by strain ZJW-6, while secretions of strain DA-25 inhibit this compound leading to an increase in the growth and enzyme activity of strain ZJW-6.