Screening, Identification And Characteristics Of High Efficient Lignocellulose Degrading Bacteria From Tobacco Waste Extract

Lignocellulose is the main content of tobacco cell wall,which has roles on the smoking quality and safety of cigarettes.Cellulose in tobacco can promote burning property,however high content of which will result in tobacco leaf tissue being coarse,increasing of moisture absorption and shorting shelf life,and increasing the irritating smoke.The premise of degradation cellulose in tobacco is to deal with lignin,the structure of which is firm and density.Moreover,high lignin content in the tobacco products can also cause dry mouth and promote the activity of cancer.Therefore,tobacco peduncle containing high content of lignin,usually be discarded and cause the waste of resources.During the process of reconstituted tobacco manufacturing,it is possible to regulate and control the content of cellulose and lignin in reconstituted tobacco products.It will be helpful to reduce the tobacco harm to human,recycle the natural resources,and protect environment.Thus,it is necessary to isolate lignocellulose degrading microbial strains to treat tobacco waste.Tobacco waste extract(TWE)is the most important raw materials during the process of reconstituted tobacco,which containing high content of sugar and nicotine with high osmotic press.TWE contains rich microbial species,it is a potential source to isolate lignocellulose degrading microbes,which is feasible to be utilized the tobacco production.In this study,a large amount of cellulose and lignin degrading strains were isolated from concentrate TWE samples,among which strain D7 showed best effect.After identification of morphology,biochemistry and physiology,and 16S rRNA sequence analysis,D7 was found belonging to genus Paenibacillus and then is named as Paenibacillus sp.D7.In a medium containing sodium carboxymethyl cellulose,the biomass of Paenibacillus sp.D7 reach maximum 9.465 mg/mL after 1day with specific enzyme activity reached maximum 0.377 U/mg.In medium containing filter paper as the sole carbon source,the biomass of D7 increased obviously after 1 day,while most filter paper collapsed completely after 8 days.Strain Bacillus subtilis SM,preciously isolated from TWE,showed both function of cellulose and lignin degradation.HPLC,TOC,GPC,and decoloring test were used to evaluate the lignin degradation.In inorganic salt medium containing kraft lignin(KL)as the sole carbon source,Bacillus subtilis SM showed obvious activity of lignin degradation after 4d culture at pH7.0 and 30?.Decoloring rate of SM reached 40.7%,however,lignin mineralization rate only reached 5.4%.Additionally,Bacillus subtilis SM showed better degrading activity of low molecular weigh lignin of KL(M_W=500)than that of high molecular weigh lignin of KL(M_W=10000).Paenibacillus sp.D7 and Bacillus subtilis SM also showed degrading effect on cellulose and ligninof tobacco steam or solid substances in TWE during the process of"reconstituted tobacco".Therefore,the both strains are potential for application to improve tobacco waste recycle and environmental protection.