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214 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYfruits [5]. The use of fruit as a substrate for lactic fermentation also offers the benefit of incorporating tastes and nutrients unique to each variety of fruit, resulting in products with distinct sensory and physicochemical properties [5]. This study used Lactobacillus plantarum, L. acidophilus, and L. casei strains to ferment myrtle fruit puree (MFP) to evaluate the potential applications of myrtle fruit. 2. MATERIALS AND METHODS Fresh myrtle fruit was collected in Do Luong district, Nghe An province, and stored at -20oC until use. Lactobacillus strains (L. casei, L. acidophilus, and L. plantarum) were provided by Biogreen Pharmaceutical and Biotechnology Joint Stock Company; Escherichia coli ATCC 25922, Methicillin-resistant Staphylococcus aureus 3640 (MRSA), and Staphylococus aureus KCTC 1916 were provided by Professor Jae Kyung Sohng, Sun Moon University, Korea.2.1. Myrtle fruit puree fermentationFresh myrtle fruit was ground with water at the ratios of 100%; 50% and 20% (w/v). The puree was autoclaved at 121oC, 1.5 atm for 20 minutes to be used for fermentation experiments. The bacterial strains L. casei, L. acidophilus, and L. plantarum stored at -80oC were activated on MRS agar medium. Then, the strains were inoculated in 5 mL of liquid MRS medium, shaking at 37oC for 4-6 hours, until the OD600 reached about 0.6 - 0.8. A 10%-ratio of bacterial suspension was added to the MFP, mixed well, and incubated at 37oC for 5 days without shaking. 2.2. Determination of bacterial density The 5-day fermented MFP was diluted and spread on MRS plates and incubated at 37oC for 24 hours to determine bacterial density.