Study of the optimal conditions of levan production from a local isolate of Bacillus subtilis subsp. Subtilis w36

Abstract

The present study was aimed to test optimum conditions for the levan production from local isolation Bacillus subtilis subsp. subtilis w36, which was isolated from Basrah city soil by using production medium containing (40 g of sucrose as carbon source 10g pepton, 1g (NH4) 2SO4, 1g KH2PO4, 1g MgSO4.7H2O). The amount of levan produced was 4.9 g.ml-1. Molasses and date juice were used as substitutes for sucrose in growth media and substitute percentages were (25%, 50%, 75% and100%). The results showed the highest production of levan was recorded when sucrose was substituted with 25% molasses, which was 5.2 g.ml-1.Therefore, this medium was used to study optimum conditions included incubation period, inoculation volume, temperature,initial pH. The highest production of levan was 6.8 g.100 ml-1 within 40 hours' incubation, 1 ml inoculum volume, pH 6.5 and 32 ºC.