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SECTION II. APPLIED BIOTECHNOLOGY IN THE PHARMACEUTICAL INDUSTRY... 4892. MATERIALS AND METHODS 2.1. Bacterial strains and cultivationIn the present study, 30 lactic acid bacteria from fermented eggplants were preserved and provided by the VAST-Culture Collection of Microorganism, Vietnam Academy of Science and Technology. To cultivate 30 strains from the glycerol stocks, de Man-Rogosa-Sharpe agar (MRS, HiMedia) was utilized. The seed cultures were transferred to fresh MRS medium to an optical density at 600 nm (OD600) of 0.1 at 37%u00b0C for 2 days. 2.2. Extraction of EPSThe EPS produced by 30 strains were extracted by icecold ethanol from MRS medium containing 10% sucrose as described previously [10]. After fermentation, 500 mL of each culture was heated at 100%u00b0C for 10 min to inactivate enzymes and then centrifuged at 10,000 rpm for 20 min to obtain cellfree supernatant. About 4% (w/v) trichloroacetic acid (TCA) was added to remove the precipitated proteins. After that, 3 volumes of 99.5% ice-cold ethanol were added and kept at 4%u00b0C for 16 h to precipitate the crude EPS. The precipitate was centrifuged, dissolved in deionized water, and precipitated again by the addition of 3 volumes of 99.5% ice-cold ethanol for 2 times to eliminate as much protein residues. The sample was subjected to lyophilization and then weighted to calculate mg dry weight of EPS per mL of the medium (mg/mL).2.3. 16S rRNA gene sequence analysisTotal genomic DNA was extracted by the G-spin%u2122 Total DNA Extraction Mini Kit (Intron Bio), which was subsequently used as DNA template for PCR reaction. A primer pair 27F and 1429R was utilized to reaction to amplify the 16S rRNA gene via the