Analysis Of Bacterial Diversity In Ghee And Screening Of Aromatic Lactic Acid Producing Bacteria In Hami Region

Ghee has a long history and occupies a very important position in pastoral food,and is used in many aspects of food processing.There are many pastoral areas in Xinjiang,and at the same time,The vast territory contains rich microbial resources,and the distribution of microorganisms varies in different pasture areas.In this experiment,ghee from the Hami region of Xinjiang was selected for study.The bacterial diversity in 32 ghee samples was analyzed by Mi Seq high-throughput sequencing technology to lay the foundation for the subsequent establishment of a bacterial library,from which the aroma-producing lactic acid bacteria were screened to study their aroma-producing characteristics and the flavor of fermented milk when the aroma-producing strains were used as fermenters.Academic research using the resource advantages of Xinjiang’s pastoral and microbial areas will provide a reference for the subsequent development and quality control of ghee products in the region.(1)Mi Seq high-throughput sequencing technology was used to analyze the bacterial diversity of 32 samples from Hami region,and the results showed that the bacterial taxa in 32 ghee samples from Hami region mainly belonged to two phyla and nine genera.The main bacterial phylum was Firmicutes and Proteobacteria.The main bacterial genera are Lactobacillus、Lactococcus、Acetobacter、Streptococcus、Acinetobacter、Pseudomonas、Leuconostoc、Enterococcus and Macrococcus。(2)306 strains were isolated by traditional culture method,and 37 strains with higher butanedione production were selected by V-P test,after sequencing,12 strains of Enterococcus faecalis,7 strains of Enterococcus faecium,8 strains of Lactobacillus paracasei,1 strain of Pediococcus acidilactici,1 strain of Pediococcus pentosaceus,7 strains of Lactobacillus plantarum,and 1 strain of Leuconostoc mesenteroides were identified.Removal of unusable strains to obtain 17 strains,the content of butanedione and acetaldehyde was determined and the results showed that 25-6 has the strongest aroma-producing ability.It is Lactobacillus plantarum.Analysis of acid and bile salt resistance of 7 strains of bacteria by combining their aroma production ability and fermentation time.25-4 has a high acid resistance.In the bile salt resistance test,good growth of 15-3,15-5,25-4 and 25-6.In the simulated gastrointestinal test,10-9,15-3,15-5,25-4 and LGG have better tolerance.(3)Seven strains with good aroma production performance and probiotic characteristics were selected for fermentation of yogurt.73 volatile flavor substances were determined from yogurt at different storage periods: there are 17 kinds of alcohols,17 kinds of ketones,17 kinds of acids,10 kinds of esters,8 kinds of aldehydes and 4 kinds of other compounds.The main Alcohols are 2-Furanmethanol,1,2-Propanediol,1-Hexanol,1-Pentanol and3-Buten-2-ol,2-methyl-.The main ketones are 2-Butanone,2-Heptanone,2-Nonanone,2-Butanone,3-hydroxy-,2-Propanone,3-Heptanone,2-Butanone,3-methyl-,and2,3-Butanedione.The main aldehydes are Acetaldehyde,2-furan-carboxaldehyde and Propanal.The main acids with high content are Benzoicacid,Butanoicacid,Hexanoicacid,Octanoicacid,Decanoicacid,Aceticacid and Pentanoicacid.The main esters are Aceticacid,butylester and Decanoicacid,octylester.In the analysis of the storage days of fermented milk and the composition of flavor substances,it was found that the type and content of flavor substances were more related to the storage days.