Study Of Comparison Of Biological Characteristics Of Lactobacillus From Different Sources

Lactobacillus is the largest genus in Lactobacilliaceae.Lactobacillus plantarum,Lactobacillus fermentum and Lactobacillus rhamnosus have been widely studied for their powerful probiotic functions and broad application prospects.Lactobacillus are widely distributed,such as oral,intestinal,breast milk,feces and so on;non-human sources such as natural fermented food,soil and so on.Studies have shown that different sources of lactobacillus can cause differences in functional genomics and phenotype.However,there are few studies on the differences of physiological and functional characteristics between human and non-human Lactobacillus plantarum,Lactobacillus fermentum and Lactobacillus rhamnosus.In this study,some biological characteristics of Lactobacillus were determined,and the differences of biological characteristics of different species and sources of Lactobacillus were compared by multivariate statistics.The main research contents are as follows:1 Isolation of Lactobacillus from different species and sources.The Lactobacillus was screened from the intestinal tract of Bama longevity old people,Yunnan fermented products and traditional fermented vegetables.It was enriched and cultured in MRS medium,separated and purified by marking.A total of 57 strains of Lactobacillus were isolated by Gram staining and microscopic examination.57 strains of Lactobacillus were identified by 16S rDNA,including 13 strains of human Lactobacillus plantarum,17 strains of non-human Lactobacillus plantarum,9 strains of human Lactobacillus fermentum,3 strains of non-human Lactobacillus fermentum,9 strains of human Lactobacillus rhamnosus and 6 strains of non-human Lactobacillus rhamnosus.2.The physiological and functional characteristics of Lactobacillus.Some biological characteristics of 57 strains of Lactobacillus were determined.The results showed that different Lactobacillus could coagulate milk in 16 h?40 h,the lactic acid degree of fermented milk ranged from 26.98 °T to 88.89°T,the viable number of fermented milk ranged from 7.82 log CFU/mL to 9.36 log CFU/mL and the water holding capacity of fermented milk ranged from 43.63%to 78.11%.The survival rate of Lactobacillus was 0.01%?104.63%at pH 2.0.The survival rate at pH 3.0 ranged from 35,56%to 170.54%.The survival rate of 0.1%bile salt was 0.01%?153.33%.The survival rate of 0.3%bile salt was 0.01%?67.17%.The self aggregation ability of Lactobacillus was 0.73%?71.11%,hydrophobicity was 1.48%?71.81%,and the adhesion to Caco-2 cells was 2.27%?50.71%.The results showed that the diameter of inhibition zone of Escherichia coli,Bacillus subtilis and Salmonella were 1.31 cm-3.92 cm,1.12 cm?3.54 cm and 1.05 cm?4.38 cm,respectively.The antioxidant capacity of gprot and its fermentation broth were 0.74 mmol/gprot-0.93 mmol/gprot respectively.After Lactobacillus intervention,the TNF?? secretion of RAW264.7 was 45.53 pg/mL?1062.19 pg/mL.3.The study on the difference of the characteristics of different Lactobacillus was carried out.Some physiological and functional characteristics of 57 strains were treated by box plot.Independent sample t-test showed that the number and acidity of Lactobacillus from human sources were significantly higher than those from non-human sources(p<0.05).The tolerance of human Lactobacillus to pH 3.0 and pH 2.0 was significantly higher than that of non-human Lactobacillus(p<0.05).The antioxidant capacity in vitro and adhesion capacity of human Lactobacillus in vitro were significantly higher than those of non-human Lactobacillus(p<0.05).Principal component analysis of different species and source strains.The physiological and functional characteristics of Lactobacillus were analyzed by principal component analysis.The results showed that:principal component 1(PC1)and principal component 2(PC2)covered 40.9%of clotting time,acidity,viable count,pH 3.0 acid tolerance,0.3%bile salt tolerance,self polymerization,hydrophobicity,adhesion ability,antioxidant capacity of fermentation broth,inhibition ability of Escherichia coli and immune regulation ability.The PC1 and PC2 were 23.7%and 17.2%,respectively.The PC1 and PC2 scores of strains were analyzed by independent sample t-test from the perspective of source and species.The PC1 score of human strains was significantly higher than that of non-human strains(p<0.05).The score of PC2 was significantly higher than that of non-human strains(p<0.01).4.The physiological and functional characteristics of 57 Lactobacillus strains were treated by box line diagram.The characteristics of 57 strains of Lactobacillus were analyzed by one-way ANOVA.It was found that the clotting time of Lactobacillus rhamnosus was significantly lower than that of Lactobacillus plantarum and Lactobacillus fermentum(p<0.05).The number of viable bacteria and acidity of fermented milk were significantly higher than those of other Lactobacillus(p<0.05).The survival rate of Lactobacillus rhamnosus at pH 2.0 was significantly higher than that of the other two strains(p<0.05).The order of survival rate of Lactobacillus at pH 3.0 was Lactobacillus rhamnosus>Lactobacillus plantarum>Lactobacillus fermentum.The order of survival rate of 0.3%bile salt was Lactobacillus plantarum>Lactobacillus fermentum>Lactobacillus rhamnosus.After intervention,the order of TNF-? content in supernatant of immunocompromised RAW264.7 cells was Lactobacillus rhamnosus<Lactobacillus plantarum<Lactobacillus fermentum(p<0.05).Principal component analysis of biological characteristics of different species of Lactobacillus.In PC1,the score of Lactobacillus rhamnosus was significantly higher than that of Lactobacillus plantarum and Lactobacillus fermentum(p<0.05),but there was no significant difference in PC2(p>0.05).