The Screening Lignin Degrading Strains Of Caragana And Study On Its Fermentation Technology

At present,there are a large number of Caragana korshinskii resources in Inner Mongolia.Because of the lack of effective ways of recycling and utilization,a large number of Caragana biomass is burned every year,the utilization value of perennial Caragana korshinskii is seriously reduced due to its with high lignified degree.This study screen two strains that degrade the lignin of Caragana korshinskii,and their degradation conditions and treatment process were preliminarily explored,which provided a theoretical basis for the high value utilization of biodegradable Caragana resources.The main results are as follows:(1)107 strains of Caragana korshinskii degrading bacteria were screened from livestock manure and Caragana korshinskii humus by Caragana korshinskii as the sole carbon source.45 strains with decolorizing ring were screened by using aniline blue plate decolorization method.21 strains with larger decoloring ring were tested for lignin degradation enzyme activity and liquid fermentation of Caragana korshinskii lignin.The strains with good lignin-degrading effect were identified as N10(Bacillus licheniformis)and Y1(Bacillus subtilis).(2)The partial degradation conditions of strains N10 and Y1 were optimized by single factor and orthogonal test to improve the lignin degradation efficiency.The results showed that the optimum degradation conditions of strain N10 were peptone as nitrogen source,initial pH 7.0,culture temperature 33?,Mn2+concentration 0.6 mmol/L and inoculation volume 12%,lignin degradation rate reached 17.56%.The optimum degradation conditions of strain Y1 were peptone as nitrogen source,initial pH 6.5,culture temperature 30?,inoculation volume 10%,and Mn2+concentration 0.6 mmol/L.The highest degradation rate was 14.31%.(3)Lignocellulose in Caragana korshinskii was degraded by different fermentation technology and hydrolyzed by high-efficiency cellulose hydrolase.The results showed that after pretreatment with lignin-degrading bacteria N10 and lactic acid bacteria Sl,cellulase was used to saccharify cellulose,which could effectively improve the hydrolysis efficiency and increase sugar production.In group A,the lignin degradation rate,hemicellulose degradation rate and cellulose degradation rate were 18.47%,9.87%and 4.43%respectively.After cellulase hydrolysis,the contents of total reducing sugar and glucose in the hydrolysate were 1.82 g/L and 0.86 g/L,respectively.The conversion rates of total reducing sugar and glucose increased significantly,reaching 30.64%and 14.48%,respectively.Compared with the blank group,the conversion rate of Caragana korshinskii was increased by 4.23 times,which provided a basis for the fermentation technology of Caragana korshinskii biomass.