Diversity of culturable bacteria in lactating Bactrian camels in Jimunai area of Xinjiang during winter and the acid-and enzyme-producing activities

Abstract:

[Objective] Culturable bacteria were isolated from camel and the distribution of bacteria was analyzed.On this basis,the acid-producing and enzyme-producing bacteria were screened out.This study is expected to provide resource and technical support for the development and utilization of camel-derived probiotics.[Methods] Serial dilution-coating method was used to screen bacteria in milk,saliva,and rectal feces of lactating Bactrian camels in Jimunai area of Xinjiang in winter,and the strains were identified by 16S rRNA gene sequencing.Strains producing acid and enzyme were identified with the transparent circle method,and the ability of producing organic acid,amylase,cellulase,and protease was further evaluated.[Results]A total of 63 bacterial strains were cultured,with 35 strains from camel feces (mainly Psychrobacter and Acinetobacter),21 from camel milk (dominated by Pseudomonas and Leuconostoc),and 7 from saliva (mainly Bacillus).A total of 11 acid-producing strains were screened out,with the feces-derived Leuconostoc mesenteroides 2F11M yielding the most lactic acid (up to 3.93 mg/mL),milk-derived L.lactis 2N5M achieving the highest acetic acid yield (12.73 mg/mL),and the feces-derived Enterococcus Mundtii 2F17M topping the bacteria in propionic acid yield (10.36 mg/mL).According to the transparent circle,the enzyme-producing strains were mainly from camel feces and camel milk.Among them,17,10,and 15 strains produced amylase,cellulase,and proteinase,respectively.The milk-derived Bacillus velezensis Nai1 had the highest amylase activity (509.07 μg/min/mL) and feces-derived Acinetobacter lwoffii 2F5N had the highest cellulase activity (156.87 μg/min/mL).In addition,milk-derived B.subtilis 2N2N achieved the highest protease activity (3.59 μmol/min/mL).[Conclusion] A variety of acid-producing and enzyme-producing strains with high activities were screened from lactating Bactrian camels in Xinjiang,which have the potential for the preparation of microecologics.