山羊原奶中可培养乳酸菌多样性及菌株的体外益生特性分析

Diversity and in Vitro Probiotic Characteristics of Culturable Lactic Acid Bacteria from Goat's Raw Milk

本研究旨在了解新疆地区山羊原奶中乳酸菌的益生特性、加工特性和安全性,以期为开发功能性乳品奠定一定的基础。实验采用16S rRNA基因测序结合Rep-PCR指纹分型技术对分离出的乳酸菌菌株进行遗传差异分析,检测它们对酸和胆盐的耐受性并对耐受性较好的菌株进行模拟胃肠液耐受性、细胞表面特性(疏水性和自凝聚)、抗菌活性、工艺逆境耐受性(溶菌酶、热)及药敏试验,来评价菌株的体外益生特性和安全性,通过主成分分析筛选最优的益生菌株。研究从15份山羊乳样品中共分离得到23株乳酸菌,包括Leuconostoc mesenteroides(9株)、Lactiplantibacillus plantarum(6株)、Latilactobacillus curvatus(4株)、Enterococcus faecium(2株)、Enterococcus durans(2株)。基于对酸和胆盐耐受性进行初筛的结果表明,有7株菌具有较好的耐受性。其中,2株植物乳植物杆菌(L. plantarum SY43-10和L. plantarum SY43-4)的模拟胃液和肠液处理后活菌数均高于5 lg CFU/mL;24 h自凝集率大于27%、并具有良好疏水性;热和溶菌酶处理后的活菌数仍大于7 lg CFU/mL;药敏试验显示2株菌对氨苄西林和氯霉素表现敏感,对头孢西丁、红霉素和青霉素表现中度敏感或敏感。因此,菌株SY43-10和SY43-4可作为优良的益生菌株,通过体内实验进一步应用于发酵乳品和功能性产品。

This study was to assess the probiotic attributes,technological properties and safety profiles of lactic acid bacteria isolated from local raw goat milk in Xinjiang,and built a cornerstone of exploitation of functional dairy products.Isolates were analyzed the genetic differences by 16S rRNA gene sequence combined Rep-PCR fingerprint typing technology.Preliminary screening under acid and bile salt base conditions were conducted and before the following experiments,including simulated gastrointestinal fluid tolerance,cell surface properties(hydrophobicity and autoaggregation),antimicrobial activity,processing stress tolerance(lysozyme and heat),and antibiotic sensitivity.Principal component analysis(PCA)was used to identify and screen the strains with optimal probiotic properties.This study found that the 23 lactic acid bacteria strains were isolated from 15 goat milk samples,including Leuconostoc mesenteroides(9 isolates),Lactiplantibacillus plantarum(6 isolates),Latilactobacillus curvatus(4 isolates),Enterococcus faecium(2 isolates)and Enterococcus durans(2 isolates).Seven strains were able to maintain considerable viable bacterial counts under pH2.0 and 0.3%bile salt conditions,indicating their high tolerance to acid and bile salt.Among them,strain SY43-10 and strain SY43-4 possessed a high tolerance towards simulated gastrointestinal fluid with over 5 lg CFU/mL after treatment,high self-agglutination rates of over 27%after 24 h and high hydrophobicit.Meanwhile,the viable counts after heat and lysozyme treatment of these two strains were more than 7 lg CFU/mL.Both of the two strains were susceptible to ampicillin and chloramphenicol,and were intermediate or susceptible to cefoxitin,erythromycin,and penicillin.In conclusion,strains Lactiplantibacillus plantarum SY43-10 and Lactiplantibacillus plantarum SY43-4 can be used as potential beneficial strains for further development of fermented dairy and functional products.