Effects Of Lactic Acid Bacteria And Enzyme Preparation On Fermentation Quality And Microbial Diversity Of Rice Straw Silage

The objective of this paper is to improve the utilization rate of straw forage.The degradation rate of cellulose,hemicellulose and lignin in straw was improved by silage fermentation.In addition,Miseq high-throughput sequencing technology was used to analyze the microbial diversity in straw silage process and understand the composition and changes of microorganism a in straw silage.Therefore,the utilization of straw resources can be realized from the perspective of microorganism.1.Effects of different lactic acid bacteria on the fermentation quality of rice straw silageThe aim of the test was to study the effects of different types lactic acid bacteria on the fermentation quality of rice straw silage.Different types of lactic acid bacteria were added to straw for silage.At the time of silage 1,3,5,7,14,28,42 and 63 d,bagged samples were opened resperctively,and the effects of silage additives were evaluated by analyzing the changes of organic acid and microbial population during silage,so as to select the best silage additive.There were 5 treatments in the experiment,including control group(CK),Lactobacillus plantarum(ZR),Lactobacillus buchneri(BR),Lactobacillus casei(GR)and Lactobacillus complex(FR).The results showed that the treatment group significantly reduced the pH value,propionic acid,butyric acid and ethanol content,and increased the lactic acid content(P<0.05).Both GR and FR groups significantly reduced the acetic acid content(p<0.05).The quantity of lactic acid bacteria in silage was increased and aerobic bacteria and fungi were reduced in all treatment groups(p<0.05).Compared with other treatments,the FR group had the lowest pH,higher lactic acid content,and lower acetic acid,butyric and alcohol content.It is also more effective in inhibiting aerobic bacteria growth.Considering the effect of rice straw fermentation,it is suggested to use compound bacteria as straw silage additive.2.Effects of lactic acid bacteria and enzyme preparation on nutrition and fermentation quality of straw silageThe aim of this test was to study the effects of lactic acid bacteria and enzyme preparation on nutrition and fermentation quality of straw silage.The control group(CK),lactic acid bacteria(J),compound enzyme preparation(M),and bacteria add enzyme group(JM)were used to determine the fermentation quality and microbial dynamics at the early(7 d),middle(30 d)and late(60 d)stages of silage.The results showed that compared with CK group,the starch content in straw silage was significantly increased in treatment group,but the difference between treatment groups was not significant(p>0.05).IVDMD was also significantly increased in the J and JM group(p<0.05).The WSC content in treated groups were significantly decreased(P<0.05),The content of NDF and ADF in silage was decreased in JM group and increased in J group(P<0.05),but there was not significant compare with CK.During the whole silage process,the pH value,butyric acid and ethanol content of silage were significantly reduced in the treatment group(P<0.05).The contents of lactic acid and acetic acid in J group and JM group were significantly increased(p<0.05).The population of lactic acid bacteria in silage was significantly increased and aerobic bacteria and fungi were significantly reduced in all treatment groups(p<0.05).Compared with other treatment groups,the combination of lactic acid bacteria and enzyme preparation resulted in higher IVDMD,lower pH value,lower NH3-N/TN,and lower number of aerobic bacteria in silage.3.Study on microbial diversity during rice straw silage processThe dynamic changes of microbial diversity and composition during rice straw silage were analyzed by Miseq high-throughput sequencing.The results show that:(1)During the fermentation of rice straw silage,the bacterial abundance showed a declining trend.Based on the classification level of phylum,the main dominant bacteria in straw silage were Firmicutes,Proteobacteria and Actinobacteria.Except CK group,Firmicutes were always dominant in straw silage of treatment group.The relative abundance of Firmicutes in JM group was the highest.At the classification level of genus,the unidentified bacterial genera were dominant in the whole silage process of CK group.When silage time was prolonged,the relative abundance of Lactobacillus increased and the relative abundance of Weisiella decreased in all groups.Compared with CK group,Lactobacillus was relatively abundant in the treatment group.The relative abundance of lactobacillus in JM group was 90.40%(2)During the fermentation of rice straw silage,the abundance of fungi in all groups increased firstly and then decreased.Based on the classification level of phylum,the additives had few effect on the relative abundance of in rice straw silage.Ascomycota was the dominant fungal phylum in all groups,accounting for 88.36%to 96.67%of the total fungal abundance in the whole silage process.Based on the classification level of genus,the use of additives changed the dominant fungi in rice straw silage.Compared with CK group,Pichia was the dominant genus in the treatment group of J and JM.