Screening of 42 Bacillus isolates for ability to ferment soybeans into dawadawa

Abstract

Forty-two cultures of Bacillus species isolated from soybean dawadawa were screened for their proteolytic activity on Skim Milk Agar, amylolytic activity on Starch Agar, and ability to grow on Soybean Agar. Distinct differences were observed between the cultures for all the criteria. Eleven isolates were selected for laboratory fermentation trials and each produced soybean dawadawa which was found acceptable by a taste panel. The pH of the samples, which increased from 6.37-6.58 to 8.22-8.85 during fermentation, were significantly different at P ≤ 0.05 for the different cultures. In the fermented samples, Bacillus counts exceeded 109 cfu/g, with the population of only one sample being significantly different at P ≤ 0.05. A market focus group familiar with soybean dawadawa selected Bacillus subtilis 24BP2 and B. subtilis FpdP2 as the best potential starter cultures. A taste panel found no significant differences in overall acceptance between soybean dawadawa either fermented spontaneously or with B. subtilis 24BP2 and also between soybean dawadawa fermented with either B. subtilis 24BP 2 or B. subtilis FpdP2.