Effect of different carbon doses of tapioca (Manihot esculenta) flour on vegetative cells and spore production of Bacillus megaterium

Bacillus megaterium is a spore forming bacteria that is mostly used as a probiotic in aquaculture. Spore formation for probiotic production using carbon source is costly. This research evaluated the effect of different carbon doses of tapioca (Manihot esculenta) flour on vegetative cells, spore production, sporulation efficiency and spore germination of B. megaterium. Experiments were carried out in Aquaculture Laboratory, University of Brawijaya. In flasks, 50 ml of growth media were used and were inoculated with 1% of B. megaterium (2.6 x 10⁸ cells/ml). The cultures were mixed (120 rpm) and incubated at 37 °C for 120 hours with 4 different treatments of carbon doses (5, 10, 15 and 20 g/L, respectively). The results showed that the highest vegetative cells (8.4 x 10⁷ cell/ml) and spore production (4.1 x 10⁷ spore/ml) of B. megaterium were found at 15 g/L carbon dose. However, it was not followed by high sporulation efficiency (only 49.01%). The high spore germination was observed in more than 5 g/L carbon dose. Thus, 5-15 g/L carbon doses of tapioca flour could positively enhance vegetative cells, spore production, sporulation efficiency and spore germination of B. megaterium and could be used as a potential source of probiotics in aquaculture.