Isolation and Identification of Pediococcus lactis in Human Intestinal Tract and Its Performance Analysis of Fermented Goji Berry Juice

In order to obtain candidate strains with strong colonization ability and excellent fermentation performance of goji berry juice, 3 strains of lactic acid bacteria were isolated and screened from human intestinal tract. They were identified by morphological, physiological and biochemical, 16S rDNA sequence analysis and phylogenetic tree construction, and their acid resistance, bile salt resistance, artificial gastric fluid, intestinal fluid resistance and fermentation performance were studied. The results showed that all three strains were identified as Pediococcus lactis, numbered NXU_220218, NXU_220219 and NXU_220220, respectively. The growth rate from 2 to 8 h, the ability of NXU 220218 to produce acid was stronger, and the tolerance to acid, bile salt and artificial gastric juice was better than NXU 220219 and NXU 220220. The survival rate of NXU_220218 was 67% at pH2, 65% in bovine bile salt at 0.3% concentration, 72% tolerance to artificial gastric juice, and 95% tolerance to artificial intestinal juice. Finally, the NXU_220218 strain was inoculated and used in the preparation of fermented goji berry juice. It was found that the reducing sugar content and the free radical scavenging rate in the fermented goji berry juice were significantly reduced and increased, respectively, compared with the unfermented goji berry juice, indicating that the NXU_220218 strain had good fermentation performance for goji berry juice and could be used as a candidate strain of lactic acid bacteria for the fermentation of goji berry juice.