Probiotic evaluation of Bacillus subtilis PZ014383 and application of its keratinase in eco-friendly hide dehairing

Abstract

The current study focused on the assessment of probiotic potential and biotechnological applicability of the Bacillus subtilis (B. subtilis) PZ014383 strain by means of various in vitro analyses. The strain demonstrated the ability to withstand simulated digestive stress, with viability in simulated gastric and intestinal conditions being 72.51% after 3 hours at pH 2.0 and 60.71% in 0.3% bile salts, respectively. Survival in the presence of increasing concentrations of phenol decreased from 8.62 to 7.68 log CFU/mL at 0.6% phenol. Antibiotic testing showed susceptibility to meropenem, moxifloxacin, and rifampicin, whereas several beta-lactams, including ceftriaxone and cefotaxime, produced no inhibition zones. The cell-free supernatant (CFS) demonstrated selective antimicrobial activity with a 12.33 mm inhibition zone against Staphylococcus aureus (Staph. aureus) (ATCC 259233) and no inhibition of Escherichia coli (E. coli) (ATCC 25922). The tested strain tolerated 8% NaCl and displayed favorable surface characteristics, including 89.27% auto-aggregation and 73.3% hydrophobicity, with co-aggregation with E. coli being 19.34%. The γ-hemolysis result showed the absence of hemolytic activity. The keratinase enzyme produced by this strain demonstrated the ability to dehair hides effectively, serving as a more environmentally friendly biotechnological alternative to the chemical process.