Screening Of Cellulose-degrading Bacteria From Bactrian Camel And Th E Application In Distiller's Grains

As the main livestock species in desert and semi-desert areas,camels have unique physiological functions after long-term natural selection.However,there are few studies on cellulose-degrading bacteria which exists in the intestinal system of bactrian camel.In order to explore the bacteria that have the ability to degrade cellulose in the feces of bactrian camel,this study used the carboxymethyl cellulose sodium(CMC-Na)plate method for screening and completed separation and identification.Furthermore,the DNS method was used to measure cellulase viability in this experiment.According to the size of the transparent circle and cellulase viability,strains with strong cellulose degradation ability was selected.Afterwards,these screened strains were identified combining comprehensive factors,including morphological observation,physiological and biochemical characteristics,and results of 16S rRNA sequencing analysis.At the same time,the fermentation conditions of the strains were optimized by single factor experiments and response surface methodology,and the enzymatic stability of the crude enzyme obtained by fermentation were studied.The strains obtained by fermentation were inoculated in distiller's grains,and the degradability of the screened strains on cellulose and hemicellulose in distiller's grains was investigated.The results showed that the strains with strong cellulose degradation ability were YT5-1-1 and YT3-1,according to the identification,YT5-1-1 is Enterobacter xiangfangensis and YT3-1 is Bordeella Petrii.The optimized parameters of strain YT5-1-1 are:inoculation volume 2.6%,initial pH 4.6,incubation temperature 30?,fermentation time 43 h,and the actual CMCase viability is 1.561 ±0.103 IU/mL;The optimized parameters of strain YT3-1 are:inoculation volume 5.6%,initial pH 7.0,incubation temperature 35?,fermentation time 84 h,and the actual CMCase viability is 1.620±0.067 IU/mL.The two strains have good acid-base stability and heat resistance.Inoculated the selected strains in distiller's grains,the results show that the strains YT5-1-1 and YT3-1 have no effect on the pH changes during the fermentation of distiller's grains,and can maintain a higher dry matter content and significantly reduce the neutral detergent fiber content and acid detergent fiber content;At the end of fermentation,the degradation rate of hemicellulose and degradation rate of cellulose values for the YT5-1-1 group are increased by 4.18%and 3.46%respectively compared with the blank group,and for the YT3-1 group,the values are increased by 12.49%and 3.83%respectively compared with the blank group,indicating that strains YT5-1-1 and YT3-1 can effectively reduce the cellulose in distiller's grains and have practical application value,as well as significantly improve the feed quality value of distiller's grains.