Isolation, selection and identification of lactic bacteria from pickled salt lotus root in Giang Thanh district, Kien Giang province

The study was conducted to isolate, select, and identify the lactic acid bacteria strain with the highest lactic acid fermentation ability from pickled lotus root products in Giang Thanh district, Kien Giang province. From three samples of pickled lotus root collected in Giang Thanh district, 11 lactic acid bacteria strains were isolated and preliminarily identified through colony morphology and some biochemical reactions such as Gram staining and catalase reaction. The results of determining the fermentation type showed that all 11 isolated bacterial strains had a homomorphic fermentation type, the main fermentation product was lactic acid. Of which, strain D15 had the highest lactic acid content, reaching 1.87 mg/mL and had the highest biomass growth ability, with an OD600nm value of 0.947. The 16S rRNA gene sequence of strain D15 was determined with a molecular size of 1469 bp. Comparing the 16S rRNA gene sequence of strain D15 on the gene bank, it has a similarity level of 100% with some lactic acid bacteria strains of the species Lactobacillus plantarum and 99.68% when comparing with the 16S rRNA gene sequence of the standard strain Lactobacillus plantarum. Constructing a phylogenetic tree and evaluating the genetic relationship of strain D15, the standard strain Lactobacillus plantarum, and 9 strains with the highest similarity to strain D15 based on the 16S rRNA gene sequence. The results were classified into 2 large groups with a similarity level of 92%, in which strain D15 is in the same group as the standard strain Lactobacillus plantarum and also has a similarity level of 92%.