OPTIMIZATION OF ENHANCED PROBIOTIC SPORES PRODUCTION IN SUBMERGED CULTIVATION OF BACILLUS AMYLOLIQUEFACIENS B-1895

Abstract

The aim of this study was to gain a deeper fundamental knowledge on the physiology of B. amyloliquefaciens B-1895 for development of probiotic production technology through the submerged fermentation of renewable and inexpensive agro-industrial lignocellulosic biomass.
For comparison, bacilli cultivation was performed in the synthetic medium with different carbon sources. The highest yield of spores (7.1 x 109/mL) was attained after 72 h of submerged cultivation of bacilli in the 0.4% glucose-containing medium. Substitution of glucose with various lignocellulosic materials at concentration of 40 g/L yielded 2.3-10.8 x 109 spores/mL. After subsequent optimization, the developed simple medium containing milled corn cobs as a growth substrate and casein hydrolysate at concentration of 40 mM N provided formation of as high as 2.8 x 1010 spore/mL in shake-flasks experiments and 2.5 x 1010 spores/mL in a laboratory fermenter enabling the large scale production of low-cost probiotic for their biotechnological application. The study underlines importance for the efficient sporulation of carbon source depletion at the end of the exponential growth phase. Moreover, it shows that an exploitation of lignocellulosic materials with an appropriate chemical composition is a reasonable way to achieve high cell density and sporulation since bacilli secrete sufficient levels of glycosyl hydrolases for substrate saccharification to ensure bacterial culture with carbon and energy source.