Isolation of Lactic Acid Bacteria from Water Kefir Grains and Characteristic Analysis of their Fermentation of Litchi Juice

The fermentation of lactic acid bacteria can retain the original flavor of litchi and endow it with new storage performance and nutritional value. In order to expand the fermentation agent resources, Lacticaseibacillus paracaseis subsp.tolerans FJAT-54886 and Liquorilactobacillus satsumensis FJAT-54887 were isolated from water kefir grains by the separation of MC culturing medium, morphological observation, physiological and biochemical characteristics and 16s rDNA gene sequence analysis. Then, the fermentation characteristics of litchi juice were compared and analyzed among these two strains and Lactiplantibacillus plantarum FJAT-54898 and Lacticaseibacillus paracaseis subsp.paracasei FJAT-54854 which were suitable for the fermentation of plant materials. The results showed that the proliferation rate and final viable counts of Lactobacillus planturum FJAT-54898 and Lacticaseibacillus paracaseis subsp.paracasei FJAT-54854 were significantly higher than those of Liquorilactobacillus satsumensis FJAT-54887 and Lacticaseibacillus paracaseis subsp.tolerans FJAT-54886 (P<0.05). The final viable counts of the latter two was 7.36 Lg(cfu·mL^-1) and 7.02 Lg(cfu·mL^-1), respectively. The pH value of Lacticaseibacillus paracaseis subsp. paracasei FJAT-54854 and Lactobacillus planturum FJAT-54898 was significantly lower than that of Liquorilactobacillus satsumensis FJAT-54887 and Lacticaseibacillus paracaseis subsp.tolerans FJAT-54886 (P<0.05). The pH value of the latter two were 3.75 and 4.33, respectively. The acidity concentration of Lacticaseibacillus paracaseis subsp.paracasei FJAT-54854 and Lactiplantibacillus plantarum FJAT-54898 was also higher than that of Liquorilactobacillus satsumensis FJAT-54887 and Lacticaseibacillus paracaseis subsp.tolerans FJAT-54886. The acidity concentration of the latter two was 99.6^ΟT and 76.5^ΟT, respectively. The above results provided reference for the selection of strains for the development of litchi juice fermented products.