| With the gradual understanding of microbial community functions and synergistic relationships among microorganisms under natural conditions,mining microbial resources for efficient degradation of crude fibers is the key to feedstock utilization of lignocellulosic substances.Ruminant rumen is a perfect natural digestion and fermentation system and micro-ecosystem in nature,which is described as a rich resource bank of cellulolytic bacteria.This study aim is to apply the screened facultative anaerobic microbial consortia that efficiently degrade cellulose from the rumen of Holstein cows and Tibetan yaks to the silage of alfalfa and sweet sorghum.The effect of different sources of microbial consortia on the fermentation quality and structural carbohydrate degradation of alfalfa and sweet sorghum was compared to provide a scientific and theoretical basis for the application of microbial consortia in silage production.1.The enzyme production and degradation characteristics of ruminal high-efficiency facultative anaerobic microbial consortiaThe purpose of this experiment is to study the enzyme production and degradation characteristics of the facultative anaerobic microbial consortia screened from the rumen of Holstein cows and Tibetan yaks,and to provide a theoretical basis for the development and application of microbial additives in actual production.The experiment separately studied the enzyme producing characteristics of the facultative anaerobic microbial consortia CL and YL under different carbon sources and different p H;In addition,rice straw was used as material to study the effects of microbial consortia and combined addition with lactic acid bacteria on the degradation of rice straw,enzyme production dynamics and metabolites.The results showed that the enzyme activity of CL and YL were higher under the condition of natural cellulose as carbon source and p H 5.5.Will filter the microbial consortia alone or combined with lactic acid bacteria added to the simulated fermentation of rice straw,and found that the microbial consortia added alone or combined with lactic acid bacteria were significantly improved the structural carbohydrate degradation rate,lowered the p H,increased the content of organic acid,the combined additive group has the highest degradation rate of lignocellulose among them.In conclusion,the screened strains have the characteristics of acid resistance and cellulose degradation,and have a good application prospect in silage production.2.Effect of facultative anaerobic microbial consortia on fermentation quality and carbohydrate compositions of alfalfa silageThe purpose of this experiment is to study the effect of facultative anaerobic microbial consortia on the fermentation quality and carbohydrate compositions of alfalfa silage.The experiment had 6 treatment groups and 6 time points: CK(control group);Lp(Lactobacillus plantarum)group;CL group;YL group;CLP group(CL+Lp);YLP group(CL+Lp).Samples were taken and analyzed after 3,7,14,30 and 60 days of silage.The results showed that with the extension of the silage time,the p H,NDF,ADF,and soluble carbohydrate content of each treatment group showed a downward trend.In silage for 120 days,compared with the control group,the p H value of each treatment group was significantly lower(P<0.05),and the CLP and YLP groups showed the lowest.The content of lactic acid in the CLP and YLP groups were significantly higher than that in the control group(P<0.05),and the YLP group reached the maximum value(76.72 g/kg DM)after 120 days of silage.Compared with the control group,the compound strain alone or in combination with lactic acid bacteria significantly increased the soluble carbohydrate content in the silage(P<0.05).After 120 days of silage,the crude protein content of YLP group was significantly higher than that of other groups(P<0.05).In conclusion,adding microbial consortia CL and YL alone or in combination with Lp significantly improved the silage fermentation quality of alfalfa and promoted the degradation of structural carbohydrates,and the combined addition of microbial consortia YL and LP had the best effect.3.Effect of facultative anaerobic microbial consortia on fermentation quality an d carbohydrate compositions of sweet sorghum silageThe purpose of this experiment is to study the effect of facultative anaerobic microbial consortia on the fermentation quality and carbohydrate compositions of sweet sorghum silage.The experiment had 8 treatment groups and 5 time points: CK(control group),E(commercial enzyme preparation)group,CLB(compound lactic acid bacteria,including L.plantarum,P.pentosaceus,and L.buchneri),CL,YL,E+CLB,CL+CLB,YL+CLB.Samples were taken and analyzed after 3,7,14,45,90,and 120 days of silage.The results showed that during the whole silage process,the DM,NDF,and ADF contents of each treatment group showed a downward trend.Except for the CL+CLB and YL+CLB groups,the p H value showed the first decline and then an increasing trend.The p H of CL+CLB and YL+CLB reached the lowest after 60 days of silage.Except for group E,compared with the control group,the LA content of the other groups was significantly increased(P<0.05),and the AA content was significantly reduced(P<0.05).The LA/AA value of each treatment group was higher than that of the CK,of which CL+CLB and YL+CLB groups were significantly higher than other treatment groups(P<0.05).Except for the E and CLB groups,the hemicellulose content of the other treatment groups was significantly lower than that of the CK(P<0.05).There was no significant difference in the content of structural carbohydrates between the CL and YL groups(P>0.05),but their contents were lower than that of the CK,E,and CLB groups.After 30 days,the CL+CLB and YL+CLB groups maintained higher levels of water-soluble carbohydrates,sucrose,cellobiose,fructose,xylose,and glucose to varying degrees until the end of the silage.The surface structure changes of sweet sorghum silage after 60 days were observed by scanning electron microscopy,the surface morphology and structure changes of CL + CLB and YL+CLB groups were the most obvious.In conclusion: adding the facultative anaerobic microbial consortia CL and YL significantly improved the fermentation quality of sweet sorghum silage,and the combination with lactic acid bacteria could have a better effect.In summary,the research on enzyme production characteristics and degradation characteristics found that the facultative anaerobic microbial consortia(CL and YL)from the rumen of Holstein cows and Tibetan yaks have the characteristics of acid resistance and cellulose degradation.Adding microbial consortia CL and YL alone or in combination with Lactobacillus significantly improved the silage fermentation quality of alfalfa and sweet sorghum,and promoted the degradation of structural carbohydrates.The combined addition of yak rumen-derived compound bacteria YL and Lactobacillus had better effect. |
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