The Promotion Effect Of Rhodococcus Biological Pretreatment On Enzymatic Hydrolysis Of Straw Biomass

Converts a wide range of natural biomass into biofuels or biochemicals is an efficient,green and sustainable method.The cell wall of straw-like biomass has a stable structure and complex components.Various cellulose degrading enzymes cannot combine with the cellulose on the surface of the reaction substrate,which greatly inhibits the enzymatic hydrolysis of lignocellulose.A variety of pretreatment processes were used to remove the combined layer of lignin and hemicellulose in the straw biomass material,which increases the porosity of cellulose and loosens the structure,increases the effective contact area between cellulose and enzyme,and improves the saccharification efficiency of cellulase.In addition to physical pretreatment and chemical pretreatment,it has been found that the use of microbial pretreatment can improve straw utilization,which has the advantages of mild reaction conditions and no harmful byproducts,and low cultivation cost.It has great application potential in the process of straw degradation.In this study,Rhodococcus was used as a biological pretreatment strain of corn stalks,to explore the role of Rhodococcus on the enzymatic hydrolysis of straw biomass,and to find a feasible biological pretreatment method.Rhodococcus biphilus sp.B403 is a strain of Rhodococcus that can degrade aromatic hydrocarbon compounds selected from the soil in our laboratory.The strain can open the benzene ring structure through redox and decomposition into other substances.This study measured the growth of the strain in different media,selected the most suitable medium and expanded the culture in the most suitable medium,and the culture solution containing substantially no bacterial cells was obtained by low-temperature centrifugation as a crude enzyme solution for corn straw slice treatment.Corn straw powder was treated with the bacterial solution containing Rhodococcus biphilus sp.B403,it was found that pretreatment can significantly improve the enzymatic hydrolysis efficiency of corn straw,indicating that Rhodococcus pretreatment promoted the enzymatic hydrolysis of corn straw.The fiber structure of the corn straw after pretreatment was observed,and it was found that Rhodococcus had a certain destructive effect on the corn straw structure.It was observed by fluorescence microscope that the action area of Rhodococcus on corn straw was mainly concentrated in the surrounding tissues of the catheter and the sieve tube.After pretreatment,there were obvious structural changes in this area,and the decrease in fluorescence intensity to a certain extent indicated that the content of lignin had decreased.The lignin structure on the surface of the corn structure is no longer intact,and more internal cellulose structure is exposed,thereby increasing the surface area of the straw material,the availability of cellulase is increased,and the cellulase and cellulose are better combined,improve the hydrolysis effect of cellulase.In summary,this study used Rhodococcus biphilus sp.B403 to pretreat the biological straw,which promoted the enzymatic saccharification effect of cellulase on corn straw,and analyzed the destruction of corn straw structure by Rhodococcus.The principle of Rhodococcus pretreatment to promote enzymatic hydrolysis of corn stalk biomass was analyzed,and some new ideas and methods were provided for the biological pretreatment of natural straw materials.