Microbial Extraction Of Vitamins B From Lignocellulosic Biomass And Their Fermentation Applications

The long-term focus of lignocellulosic biorefinery is on overcoming the technical barriers in the process,such as pretreatment,detoxification,saccharification and fermentation and so on.Few studies concerned the high content of vitamins B in lignocellulosic biomass and their effective utilization.On one hand,the extraction of vitamins B during the biorefinery chain can improve the added value of the product and further achieve the high utilization of lignocellulosic biomass.On the other hand,the full applications of vitamins B in the straw hydrolysate not only promote the fermentation of bio-based chemicals based on the cellulose as substract,but also reduce the addition of exogenous vitamins.The fact greatly reduces the fermentation cost and exhibits superiority compared with the fermentation process of the starch substrate.The first part of thesis studied the microbial extraction of biotin from lignocellulosic biomass and its application in glutamic acid fermentation.High content of biotin in lignocellulosic biomass could be reserved during the dry biorefinery process.Compared with different biotin auxotrophic strains,Corynebacterium glutamicum S9114 was found to have the strongest ability of biotin accumulation and could effectively extract biotin from corn leaves hydrolysate(179.2?g/L biotin).Subsequently,a recombinant strain C.glutamicum S9114(pH36mob-bioYMN)having a rapid absorption ability to biotin was obtained by plasmid expression and genome integration of the gene cluster bioYMN encoding biotin transporter.C.glutamicum S9114(pH36mob-bio YMN)was as the starting strain to extract biotin from the corn leaves hydrolysate and cells were harvested.The content of intracellular biotin was about 303.8 mg/kg,which was much higher than commercial fermentation nutrient additives,such as yeast extract(YE,?2 mg/kg),molasses(?1 mg/kg)and corn steep liquor(CSL,?0.75 mg/kg).The biotin nutrient additives were successfully applied in glutamic acid fermentation to replace pure biotin and CSL.This was the first report on microbial extraction of biotin from lignocellulose feedstocks and production of nutrient additives with extremely high biotin content from biorefinery plants.In the second part of thesis studied the vitamins B in lignocellulose biomass facilitating cellulosic L-lactic acid fermentation.Vitamins B are important nutrients for many microbial fermentations.Vitamins B2,B3,and B5 were the key vitamins in L-lactic acid production using the bacterium Pediococcus acidilactici ZY271.The vitamins B in the corn stover hydrolysate partly fulfilled the vitamins B requirements of P.acidilactici ZY271 in L-lactic acid production.Therefore,supplementation of the specific vitamins B(such as VB3 and VB5)into corn stover hydrolysate led to the further increase of cellulosic L-lactic acid productivity.This study provided a new solution for enhancement of biorefinery fermentation efficiency by utilization of vitamin B compounds in lignocellulose biomass.In conclusion,this study achieved the microbial extraction of vitamins B in lignocellulosic biomass and their promotion in bio-based chemicals fermentation(glutamic acid,L-lactic acid).A new process for extracting and producing nutrient additives similar to YE,CSL was found and utilization of vitamins B in lignocellulose biomass provided a new solution for enhancement of biorefinery fermentation efficiency.