Isolation, genomic characterization, fermentation optimization, and enzymatic properties of a chitinase producing...

A novel Streptomyces violaceoruber strain BM-41, isolated from shellfish aquaculture waste, demonstrated potent chitinolytic activity (2.362 U/mL). Whole-genome sequencing revealed a 7.83 Mb genome (72.6% GC) encoding 238 carbohydrate-active enzymes (CAZymes), with 75 glycoside hydrolases (GHs). Significantly, seven chitinase genes were identified: six GH18 family members (ChiA-ChiF) and one GH19 member (Chi2a), displaying greater genetic diversity than S. albidoflavus ATCC 27,414 (45 GHs). Fermentation optimization via single-factor experiments and Box-Behnken response surface methodology yielded optimal enzyme production conditions: 4.5% colloidal chitin, 7 g/L yeast extract, 0.3 g/L MgSO₄, pH 5.0, 30 ℃, and 30% medium volume. This enhanced chitinase activity 2.37-fold (from 0.995 to 2.362 U/mL). Enzymatic characterization showed optimal activity at pH 5.0 and 50 ℃, stability across pH 4-8, and ion-specific modulation: Mg²⁺ and K⁺ increased activity by 25-30%, whereas Cu²⁺ strongly inhibited catalysis. Genomic analysis uncovered a synergistic degradation pathway involving extracellular chitinases (ChiA-ChiF) and 10 key metabolic enzymes, including N-acetylglucosaminidases (EC 3.2.1.52), deacetylases (EC 3.5.1.25), and UDP-N-acetylglucosamine pyrophosphorylases (EC 2.7.7.23). This enzymatic network facilitates efficient conversion of chitin to N-acetylglucosamine monomers and downstream metabolites. The findings contribute to the understanding of S. violaceoruber BM-41 genomic features and its potential as a source of industrially relevant enzymes.

The online version contains supplementary material available at 10.1007/s13205-025-04634-6.