Study On The Characteristics Of Guaiacol Production From Lignin By Bacillus TYF-LIM-B05

Lignin,as one of the main components of lignocellulose,is the most abundant renewable natural aromatic polymer in nature,which has a potential application prospect.Realizing the multi-channel efficient utilization of lignin is helpful to alleviate major problems such as resource constraints and environmental pollution.The special reticular structure of polyphenols makes lignin depolymerize into high value-added aromatic compounds under certain conditions,which is of great significance to the value-added utilization and resource utilization of lignin.Using biological fermentation to achieve this transformation could overcome the shortcomings of traditional physical and chemical methods,such as high energy consumption and high pollution,which shows more application advantages and development potential.In this paper,48 strains were isolated from spoilage vinegar and fermented grains.A lignin degrading bacteria,which was resistant to high temperature,acid,salt and ethanol,was further screened and named TYF-LIM-B05.It was identified as Bacillus by physiological,biochemical and molecular biology,and its 16 S r DNA sequence was 98% similar to that of Bacillus paralicheniformis KJ-16.TYF-LIM-B05 can use different kinds of monosaccharides,disaccharides,polysaccharides,alkali lignin,microcrystalline cellulose,straw,etc.as the sole carbon source for growth metabolism,showing a potential to utilize a wide range of carbon sources.The metabolites of TYF-LIM-B05 with glucose,xylan and lignin as the sole carbon source respectively were detected by GC-MS.The results showed that acetone is a common metabolite of three carbon source substrates.In addition,TYF-LIM-B05 can ferment lignin to produce guaiacol,an important platform chemical.Based on the above findings,the fermentation conditions for guaiacol production by strain TYF-LIM-B05 were studied.The optimal conditions were: the concentration of alkali lignin 15g/L,the p H 7.0,the fermentation temperature 40?,and the time 48 h.Under these conditions,the yield of guaiacol could reach 100.28 mg/L.In order to make an intensive study of the functional genes of Bacillus sp.TYF-LIM-B05 in the production of guaiacol from lignin,the whole genome of the strain was sequenced by the Illumina Hi Seq TM2000 sequencing platform.TYF-LIM-B05 has a genome size of 4.48 Mb,a GC content of 45.63%,and a sequencing depth of 58.79.It uses Gene Mark S software to predict the coding genes of bacteria,and predicts a total of 4809 genes,with a total length of 3.98 Mb.In addition,there are 208 metabolic pathways annotated in KEGG database,among which 296 genes are involved in carbohydrate metabolic pathway.CAZy database annotated laccase,quinone oxidoreductase/reductase,arylalcohol dehydrogenase and other enzymes related to lignin degradation,which confirmed the ability of TYF-LIM-B05 to degrade lignin from the perspective of functional genes.Finally,in vitro amplification confirmed the existence of laccase gene,and the related pathway of TYF-LIM-B05 metabolizing lignin to produce guaiacol was speculated based on the annotated functional genes and literature reports.The above research shows that TYF-LIM-B05 has good potential in lignin degradation and value-added utilization.