Sudy On The Dynamic Changes Of Bacterial Diversity In Whole-Plant Maize Ensilage In Different Regions Of Guizhou Province

The purpose of this study was to investigate the dynamic changes of the bacterial flora on the surface of the whole-plant maize and in the process of silage,explore the correlation between the flora distribution and temperature and precipitation,the quality of silage fermentation,the aerobic stability and the dynamic change of the bacteria population of the whole-plant maize,it provides a theoretical reference for the optimization of the whole-plant maize silage agent in guizhou.This study adopts the method of vacuum bag from three different regions in guizhou(ziyun,guanling,weining)of whole-plant maize silage,and in different fermentation stages(0 d,2 d,5 d,10 d,20 d,45 d)and aerobic corruption after sampling,nutrients,and fermentation characteristics of dynamic analysis.The second generation high-throughput sequencing technology was used to analyze the dynamic changes of bacterial community,analyze the correlation between the temperature and precipitation and the surface microorganism of whole-plant maize,analyze the silage quality and aerobic stability of the dynamic changes of bacterial community.Through the research,the following results are mainly obtained:(1)The composition of bacterial community on the surface of the whole-plant maize was significantly different under different growing environments,and the species richness and bacterial community diversity of the weining group were high,while the diversity of bacterial community was highest in guanling group.The phylum level bacteria mainly attached to the surface of the whole-plant maize in three different regions were Firmicutes and Proteobacteria,The lactic acid bacteria mainly attached to the surface of whole-plant maize in the three regions were Weissella and Lactobacillus,of which the lactic acid bacteria was higher in ziyun group and weining group,the relative abundance of non-lactic acid bacteria was higher in guanling group.On the surface of correlation analysis results,there was a significant negative correlation between bacterial species richness and temperature(P<0.01),a significant negative correlation between bacterial community diversity and precipitation(P<0.01),and the relative abundance of Lactobacillus was negatively correlated with the temperature(P<0.05).(2)Silage fermentation during the 45 d,the contents of dry matter(DM),water soluble carbohydrate(WSC),neutral detergent fiber(NDF)and acid detergent fiber(ADF)in each group all showed a decreasing trend with the prolongation of fermentation time.The content of crude protein(CP)decreased first,then increased and then decreased.The content of starch(ST)in ziyun and guanling group decreased gradually,while that in weining group first decreased and then increased.(3)Silage fermentation during the 45 d,the p H value of ziyun and guanling group showed a trend of decreasing first and then rising,the content of lactic acid(LA)increased first and then decreased.The p H value of weining group was gradually decreasing,the lactic acid(LA)content increases gradually.During the whole fermentation period,the content of lactic acid(LA)in guanling group was always significantly lower than that in ziyun and weining group(P<0.05).With the extension of fermentation time,the contents of acetic acid(AA),propionic acid(PA)and ammonia nitrogen/total nitrogen gradually increased in each group.In the whole fermentation process,no butyric acid(BA)was detected in each group.(4)The bacterial diversity in the samples of the whole-plant maize collected from the same region in different fermentation stages is different,and the bacterial diversity in the samples of the whole-plant maize collected from different regions in the same fermentation stage is also different.According to OTU statistics and alpha diversity index,during the whole fermentation period,the species richness of the bacterial community in weining group was higher,and the diversity of the bacterial community in guanling group was higher.During the whole fermentation period of the whole-plant maize in the three regions,the main phylum bacterial communities were Firmicutes and Proteobacteria,and the phylum dominant bacteria in the late fermentation period(starting at the 5 d of silage)were Firmicutes.Lactobacillus and Weissella were the main lactic acid bacteria in the whole-plant maize in the three regions during the whole silage fermentation process,and the dominant genus level bacterial in the whole fermentation process were Lactobacillus.Correlation analysis showed that during silage fermentation,the water soluble carbohydrate(WSC)content and the p H value were negatively correlated with the relative abundance of Lactobacillus.The p H value,the water soluble carbohydrates(WSC),starch(ST),dry matter(DM)and acid detergent fiber(ADF)content was positively correlated with the relative abundance of Weissella.Lactic acid(LA),acetic acid(AA)and propionic acid(PA)content and the ammonia nitrogen/total nitrogen positively correlated with the relative abundance of Lactobacillus.The content of neutral detergent fiber(NDF)was negatively correlated with the relative abundance of Sphingomonas and Rahnella bacteria.There was a negative correlation between the content of acid detergent fiber(ADF)and the relative abundance of Stenotrophomonas.(5)The aerobic stability of whole-plant maize silage in three regions after bagging was opened: guanling group > weining group > ziyun group.The p H value,the contents of propionic acid(PA)and ammonia nitrogen/total nitrogen in each group after aerobic spoilage were significantly higher than those in bag opening(P<0.05),while the contents of lactic acid(LA)and acetic acid(AA)were significantly lower than those in bag opening(P<0.05).(6)The bacterial species richness and bacterial community diversity of three groups of whole-plant maize silage decreased after aerobic spoilage.The phylum dominant bacteria of 3 groups of whole-plant maize silage after aerobic corruption changed from Firmicutes to Proteobacteria when bags were opened,and from Lactobacillus when bags were opened to Acetobacter bacteria in non-lactic bacteria.The correlation analysis showed that the aerobic stability was positively correlated with the relative abundance of Lactobacillus and Weissella,and negatively correlated with the relative abundance of Acetobacter.The contents of lactic acid(LA)and acetic acid(AA)were positively correlated with the relative abundance of Lactobacillus and Weissella bacteria.The p H value,propionic acid(PA)content and ammonia nitrogen/total nitrogen were positively correlated with the relative abundance of Acetobacter.This study found that the Weissella bacteria attached to the surface of the whole-plant maize in guizhou could promoted the initiation of silage fermentation.The dominant bacteria in the whole-plant maize silage process was lactobacillus.Acetobacter was the key factor affecting the aerobic stability of the whole-plant maize silage.