The isolation of exopolysaccharide-producing lactic acid bacteria from lontar (Borassus flabellifer L.) sap

Background and Objectives: Lontar (Borassus flabellifer L.) is widely grown in Indonesia and one of its products is palm sap. Palm sap contains a high level of sugar, making it suitable as a medium to increase the lactic acid bacteria (LAB) production of exopolysaccharides (EPS). This study aimed to isolate the EPS-producing LAB from palm sap and evaluate its EPS production. LAB isolation was carried out on MRS agar containing 0.5% CaCO3. Materials and Methods: The screening and production of EPS were carried out on MRS media supplemented with 10% sucrose. The molecular identification of the selected EPS-producing LAB was based on 16S rDNA. A quantitative analysis of EPS polymer dry mass and total sugar was conducted using one-way ANOVA. Results: In this study, five EPS-producing LABs were found: Fructobacillus fructosus N4, Leuconostoc mesenteroides N5, Leuconostoc mesenteroides N7, Leuconostoc mesenteroides N9, and Fructobacillus fructosus N10. The highest EPS yield in liquid media was 10.997 ± 1.591 g/L by Leuconostoc mesenteroides N7, whereas the lowest was 4.505 ± 0.459 g/L by Fructobacillus fructosus N10. Conclusion: This study found Fructobacillus fructosus strains as EPS producers that have never been reported before.