Study On The Microbial Diversity And Physico-chemical Characteristics Of Natural Fermented Camel Milk From Different Regions

Natural fermented camel milk products were a kind of natural fermented dairy product without any treatment,which has rich bacterial diversity and biotechnological potential.Natural fermented camel milk is valuable source of food for people living in the arid areas,and it is often used to treat a variety of disease with good effects.Its nutritional and medical functions are closely related to its abundant lactic acid bacteria.Therefore,it is necessary to explore the microbiota composition and diversity of the natural fermented camel milk in different regions.In this study,we sequenced the V3-V4 region of 16S rRNA genes in natural fermented camel milk of Alxa,Sonid and Xinjiang bactrian camel by Illumina Miseq platform,and the microbiota composition and diversity were compared and analyzed.The physico-chemical characteristics were also measured and their correlation with the microbial diversity was analyzed.The results of physico-chemical characteristics showed that the pH values and titratable acidity of natural fermented camel milk in different regions were significantly different(p<0.05).The pH values of Xinjiang,Alxa and Sonid bactrian camel natural fermented camel milk were 4.70±0.057,3.65±0.052 and 4.03±0.080,respectively.The titratable acidity were 95.81±3.366°T,197.2±15.251 0T and 154.4±16.858 0T,respectively.The natural fermented camel milk in three regions is mainly different in sourness,saltiness and umami.A total of 1275266 effective sequences with an average length of 447 bp and 290 OTUs were obtained.The results of Alpha diversity showed that natural fermented camel milk from Sonid has higher bacterial diversity and microbial community richness than those of Alxa and Xinjiang.At the phylum level,Firmicutes and Proteobacteria were dominant in all of them,Firmicutes was absolute dominant phylum.At the family level,the main dominant family of Alax natural fermented camel milk were Lactobacillaceae and Acetobacteraceae,while the main dominant family of Sonid and Xinjiang natural fermented camel milk were Lactobacillaceae and Streptococcaceae.The absolute dominant family was Lactobacillaceae.At the genus level,Lactobacillus and Acetobacter were dominant in Alxa samples,Lactobacillus and Lactococcus were dominant in Sonid and Xinjiang samples.Then the Lactobacillus was the absolute dominant genus.In addition,we also found Bifidobacterium,Wolbachia and Delftia in the Alxa and Sonid samples and not detected in Xinjiang samples.This study also detected the harmful genus Shigella.The correlation analysis between the microbial diversity and physico-chemical characteristics in natural fermented camel milk from different regions showed that the Alxa and Xinjiang natural fermented camel milk microbial community diversity were mainly affect the flavor,which were Bitterness,Astringency,Aftertaste-B.And they had little relationship with titratable acidity.Sonid natural fermented camel milk microbial community diversity negatively correlated with physico-chemical characteristics.Furthermore,Streptococcus and Enhydrobacter genus had the most significant effects on flavor,pH and titratable acidity(p<0.05).Lactobacillus had a significant effect on Bitterness(p<0.05)and had no effect on other flavor.