Production of Dextran from Locally Lactobacillus Spp. Isolates

Dextran is a commercially available bacterial exopolysaccharide (EPS) with several industrial applications in the food industry and in the biomedical industry as an adjuvant, emulsifier, carrier, and stabilizer. The production of dextran at the industrial level occurs through the fermentation of a sucrose-rich medium. Research to optimize dextran production has found that the yield of dextran varies depending the specific conditions for production. The aim of this study was to produce dextran and establish the optimal conditions for dextran biosynthesis from different Lactobacillus species isolated from healthy vaginal and infant stool samples.

Lactobacillus spp. were isolated and identified from vaginal and infant stool samples via the VITEK 2 system. The presence of dextran biosynthesis from the different Lactobacillus spp. isolates was determined by a screening test for mucoid colonies and confirmed via the ethanol precipitation method. To optimize for the maximum yield of dextran, the effects of various parameters such as temperature, incubation time, pH, inoculum size, aeration, and sucrose concentration were examined.

All Lactobacillus spp. isolates were able to produce dextran. The optimal conditions for dextran production was at 24 hours of incubation at 30 °C with 15% sucrose, 4% inoculation size at pH 7.0 in aerobic conditions. This yielded a dextran dry weight of 580 mg/100 mL.

Dextran production from Lactobacillus species isolates vagina and infant stool had the ability to produce dextran.