Increased organic acid production and decreased phytate phosphorus by high level of water content of Bacillus subtilis ATCC PTA-6737 fermentation of soybean meal

Abstract

In order to enrich soybean meal (SBM) by microbial fermentation, SBM (3 mm particle size) with 78 or 85% moisture content were inoculated with 0.0 or 1x107 CFU/g (colony forming unit) Bacillus subtilis ATCC PTA-6737 and fermented at 37 oC for 0, 24, 48 and 72 h. There was a marked decrease in pH with 85% moisture content, associated at higher organic acid production, compared to increased pH at 24 h with 78% moisture content and a gradual decrease hereafter. Bacterial growth peaked at 48 h with both moisture contents. Fermenting SBM increased crude ash level by 65%, soluble amino acid nitrogen by 2.7 folds and degraded phytic acid by 65-75%. Moreover, there was a high level of organic acid production despite of decreased crude protein by 6-7%, but the effect of high moisture level was more pronounced in all case. In conclusion, fermentation SBM with water content of 85% at 35 oC by B. subtilis provided SBM an appreciable amount of bio-functionalities such reduced phytate content, increased soluble amino acid content and more importantly fortified with organic acids. The fermented SBM can therefore be used an antimicrobial agent due to its high organic acid level in animal nutrition.