Screening And Characterization Of Cellulose Degrading Bacteria On The Surface Of Caragana Korshinskii

Cellulose is the most abundant Renewable resource on the earth.Caragana is the roughage of herbivores.Its digestibility is the key to the utilization of forage resources.Since the cellulose content in Silage of Caragana korshinskii is high and its utilization efficiency is low,resulting in waste of resources,exploring the degradation mechanism of cellulose degrading bacteria in the process of Caragana korshinskii silage can save resources of Caragana korshinskii and improve the digestibility and feed quality of livestock.This experiment used samples of caragana silage with low lactate content in the early stage of silage as research materials to select 6 strains of cellulose degrading bacteria,among which 4 strains had higher enzyme activity.Subsequently,16 S r RNA identification and physiological and biochemical identification were performed on them,and their enzyme production conditions were optimized.Finally,the degradation rate was measured by adding them to the liquid fermentation medium of caragana powder.Screening and isolating cellulose degrading bacteria with high efficiency and yield has broad application prospects.Therefore,based on the characteristics of the bacterial species,cellulose degrading bacteria in the process of caragana silage can be isolated and screened for further research.The research results are as follows:(1)Six strains of cellulose degrading bacteria were screened from Caragana during the aerobic period of silage,and four strains with high enzyme activity were selected for research.Finally,the four strains were identified as Stenotrophomonas,Alcaligenes and Pantoea spp,respectively.All 4 strains of bacteria are G-;All contact enzyme tests were positive;Both V-P test and indole test were negative;In the MR test,strains H-1 and H-6were negative,while strains H-2 and H-5 were positive.(2)The strain was optimized for enzyme production through single factor fermentation,and the results showed that the optimal enzyme production conditions for strain H-1 were30 ℃,pH 6,using peptone as the nitrogen source,with a content of 0.3g/L;The optimal enzyme production conditions for strain H-2 are 30 ℃,pH 8,ammonium sulfate as nitrogen source,and a content of 0.4g/L;The optimal enzyme production conditions for strain H-5 are 30 ℃,pH 8,and using peptone as the nitrogen source,with a content of0.4g/L;The optimal enzyme production conditions for strain H-6 are 40 ℃,pH 5,using peptone as nitrogen source,with a content of 0.5g/L,and the optimal cultivation time for all four strains is 60 hours.The four strains all obtained the best fermentation conditions,which indicated that the strains were favorable for producing enzyme and Enzyme catalysis under mild conditions.(3)Optimization of fermentation enzyme production by mixing four different strains.In liquid fermentation culture,when the temperature reaches 30 ℃,the enzyme activity reaches its peak at 28.64 U/m L;When the pH is 6,the enzyme activity is 28.56 U/m L;When peptone was used as a nitrogen source,the enzyme activity reached 32.19 U/m L at a concentration of 0.4g/L.The mixed strain reached the highest enzyme activity at 30 ℃,pH 6,incubation time 60 h,nitrogen source was peptone,and the content was 0.4g/L,indicating that the mixed strain was conducive to the production of enzyme and Enzyme catalysis under mild conditions.(4)When mixed strains were added to Caragana powder liquid medium,the cellulose degradation rate was increased from 10% to 34%,32%,30%,and increased by 20% ～24%.Adding mixed strains could improve the degradation rate of Caragana Silage.After optimizing the conditions,the indigenous strains screened from the samples of caragana silage showed a certain increase in enzyme activity.