Abstract

Bacillus spp. are a natural alternative to antibiotic therapy and are most suitable for use as probiotic feed additives to improve the growth and productivity of farm animals. The present study aimed to establish culture conditions suitable for the maximal production of probiotic bacteria spores and enzymes of Bacillus subtilis IMB-73 and Bacillus amyloliquefaciens IMB-79 in solid-state fermentation (SSF) of wheat bran, soybean flour, and cilantro. The tested lignocellulosic materials ensured rapid and abundant growth of bacilli; however, wheat bran proved to be the most suitable growth substrate, yielding the highest spore counts of 5.1 × 1011/g and 5.5 × 1011/g in the cultivation of B. amyloliquefaciens IMB-79 and B. subtilis IMB-73, respectively. Supplementation of an additional nitrogen source to the wheat bran medium resulted in a significant increase in spore productivity. In particular, peptone at a concentration of 67 mg/g substrate provided the maximum spore yield in the fermented product. Both strains secreted high endoglucanase and xylanase activities in the SSF of wheat bran. Additional nitrogen sources slightly suppressed the secretion of enzymes during the SSF of wheat bran by B. subtilis IMB-73 but increased cellulase activity in cilantro SSF by approximately 2-5 times. The ease of production and the high spore yield achieved by scaling up production in polypropylene bags demonstrated the feasibility of using the developed technology for commercialization on local agricultural farms.