Screening Of Lignin-Degrading Bacteria And Optimization Of Enzyme Production Conditions

Lignin is one of the most abundant and cheapest renewable energy sources in nature.Lignin has a variety of degradation pathways,of which biodegradation is currently recognized as the most effective way to degrade lignin.Biodegradation of lignin has broad application prospects in various industries.Many topics today focus on how to screen out efficient lignin.Lignin-degrading strains and produced higher ligninase activity.In this paper,strains with efficient lignin degradation ability were screened from the habitat.From the culture time,culture temperature,dissolved oxygen,inoculation amount,and initial pH value,it was determined that the strains secreted Laccase(Lac)enzyme activity,lignin The most influential factors and their optimal ranges of the enzyme activity of Lignin-peroxidase(Lip)and Mn dependent peroxidase(Mnp)were analyzed,and the enzyme production conditions of the strain were optimized by response surface methodology.The following conclusions were drawn from the research:(1)30 strains with lignin-degrading ability were obtained from the primary screening,and 9 strains with strong lignin-degrading ability were obtained after re-screening.By comparing the ability of three enzymes to produce Lac,Lip and Mnp,4 high-efficiency lignin-degrading strains were selected and identified as Talaromyces siamensis MJ1,Penicillium sp.MJ8,and Talaromyces verrucae respectively.Talaromyces verruculosus MJ9,Aspergillus flavipes MJ26.(2)Single-factor experiments were carried out on 4 high-efficiency lignin-degrading strains,and it was found that when the culture time was 6 d,the Lac and Mnp-producing abilities of each strain reached the best,and when the culture time was 10 d,the Lip-producing ability reached the best;The optimum temperature range for enzyme production of strains MJ1 and MJ26 is 25-35?,and the most suitable temperature for enzyme production is 30?.The temperature is 35?;strains MJ1,MJ8,MJ9,MJ26 produce better enzymes under the culture conditions of the shaker rotation speed of 120r/min;The suitable enzyme-producing inoculum amount is 2%,the optimal enzyme-producing inoculum amount of strains MJ8 and MJ9 is 2-6%,and the most suitable enzyme-producing inoculum amount is 4%;The pH value of the best enzyme production range is 4-6,and the pH value of MJ8 is 5-7.The three factors that had the greatest influence on the enzyme production ability of the four strains were temperature,inoculation amount and pH.(3)Box-behnken test design and response surface analysis were used to analyze and optimize the enzyme production capacity of strains MJ1,MJ8,MJ9 and MJ26,and the interaction and strength of each factor on the enzyme production capacity of strains were analyzed in detail.The optimum conditions for MJ1 enzyme production were temperature 30.1?,inoculation amount 1.66%and pH 5.2.Lac,Lip and Mnp enzyme activities were 109.39 U,119.47 U and 227.75U,respectively.The optimum culture conditions for MJ8 were temperature 34.1 ?,inoculation amount 4.58%and pH 5.8,under which the activities of Lac,Lip and Mnp were 78.86,91.33 and 152.32U,respectively.The optimum culture conditions for MJ9 were temperature 35.7?,inoculation amount 3.97%and pH5.0,under which the activities of Lac,Lip and Mnp were 62.64 U,98.41 U and 196.14U,respectively.The optimum culture conditions for MJ26 were temperature 30.6?,inoculation amount 2.31%and pH 5.2,under which the activities of Lac,Lip and Mnp were 66.02,76.30 and 175.83U,respectively.The results showed that there was little difference between the optimized lignin enzyme activity and the simulated predicted results,which indicated that the optimized results were reliable.From habitat in this study,4 strains with efficient strains of lignin degradation ability and it was optimized by single factor and response surface method,4 isolates of lignin hydrolytic enzyme production capacity,to provide efficient and lignin degradation bacteria enzyme production fermentation,provide a reference for biological mass degradation of lignin,and lay a foundation for the follow-up related research.