Keywords :
Bacillus,
nutritional value,
proteolytic bacteria,
solid-state fermentation,
soybean meal,
termite
บทคัดย่อ :
The present study aimed to isolate and characterize proteolytic Bacillus spp. from termite guts to test the possibility of application
for improving the nutritional value and bioactivity of fermented soybean meal (FSBM). Aerobic endospore-forming bacteria were
isolated from the gut of the termite Termes propinquus. Ten isolates with high levels of soy milk degradation were selected and tested
for extracellular enzyme production. Among them, two isolates, Tp-5 and Tp-7, exhibited all tested hydrolytic enzyme activities
(cellulase, xylanase, pectinase, amylase, protease, lipase and phytase), weak alpha hemolytic and also antagonistic activities against
fish pathogenic species of Aeromonas and Streptococcus. Both phylogenetic and biochemical analyses indicated that they were closely
related to Bacillus amyloliquefaciens. During solid-state fermentation of SBM, Tp-5 and Tp-7 exhibited the highest protease activity
(1127.2 and 1552.4 U g-1, respectively) at 36 h, and the resulting FSBMs showed a significant increase in crude protein content and free
radical-scavenging ability (P < 0.05), as well as an improvement in the composition of amino acids, metabolites and other nutrients,
while indigestible materials such as fiber, lignin and hemicellulose were decreased. The potential strains, especially Tp-7, improved
the nutritional value of FSBM by their strong hydrolytic and antioxidant activities, together with reducing antinutritional components.
เอกสารอ้างอิง :
Nualkul, M., Yuangsoi, B., Hongoh, Y., Yamada, A. and Deevong, P., 2022. Improving the nutritional value and bioactivity of soybean meal in solid-state fermentation using Bacillus strains newly isolated from the gut of the termite Termes propinquus. FEMS Microbiology Letters, 369(1), p.fnac044.
