Effect of C:N ratio on the spore production of Bacillus sp. indigenous shrimp pond

Bacillus sp SB4 was isolated from shrimp pond in East Java and screened to be a potential probiotic. Yet, this bacteria experienced decrease in number during storage in the form of vegetative cells. As Bacillus species can produce spore which able to survive in harsh condition, production of those spore will be favourable. The objective of this research was to evaluate the effect of C:N ratio on vegetative cells, spore production and sporulation efficacy of Bacillus sp. The results showed that C:N ratio influenced the vegetative, spore production and sporulation efficacy of Bacillus sp. SB4. Increase of vegetative cells of Bacillus sp was observed with the increase of C:N ratio on the media. In all treatments, the first spore could be identified after hour of 30. The highest spore production of Bacillus sp. SB4 was found in the medium with C:N ratio of 10 (5.13 x 10⁷ cells. ml^-1) with sporulation efficacy of 42.8%. High vegetative cells production did not always followed by the high spore production. The different source and concentration of C and N and may become the reasons. Optimization of C:N ratio in the growing media for Bacillus sp. SB4 is still needed for higher spore production.