Screening of lignin degrading strain BYL-7 and optimization of degradation conditions

Abstract:

[Background] Microbial degradation lignin has attracted more attention due to its characteristics of high degradation efficiency and environmental protection. [Objective] Screening highly efficient lignin degradation fungi and optimizing their degradation conditions. [Methods] High efficiency lignin degradation strains were screened by guaiacol-PDA and aniline blue plate methods, and the culture conditions were optimized by single-factor screening and response surface experiment. [Results] An efficient lignin degradation bacteria BYL-7 was screened and initially identified as Trametes versicolor by morphological and multi-sequence analysis. The single factor test proved that the initial pH, temperature and inoculum amount were the significant influencing factors for lignin degradation, and the response surface test determined that the optimal conditions for degradation lignin were initial pH 6.7, temperature 25 °C, and inoculum amount 8%. Under these conditions, the alkaline lignin degradation rate was 36.5%, which was 54.0% higher than before; the degradation rates of rice straw lignin, hemicellulose, and cellulose were 32.8%, 21.5%, and 13.2%, respectively. Among them, the lignin degradation rate was enhanced by 36.1% compared with before. Laccase activity peaked at 120.0 U/L in the 6th day, which was 25.0% higher than before; the lignin peroxidase activity reached a peak of 1 343.8 U/L in the 6th day, which was 36.0% higher than before; the manganese peroxidase activity peaked at 463.8 U/L in the 5th day, which was 31.7% higher than before. [Conclusion] The experimental results provided a useful bacteria resource for lignin degradation, but also accumulated relevant data for subsequent research on lignin.