Nano-inspired optimized valorization of agrowastes by Vagococcus fluvialis FL1 for alkaline protease production and biotechnological application

The biotechnological potential of agro-industrial wastes for microbial enzyme production is gaining significant attention due to cost-effectiveness, sustainability and advances in circular bioeconomy. This study highlights the potential of Vagococcus fluvialis FL (QR884243.1), an indigenous proteolytic bacterium isolated from a chicken feather dump site for sustainable protease production in agrowaste-based media for the first time. Melon seed shell (MS), groundnut shell (GS), and groundnut peel (GP) were effectively valorized to produce proteases having titers of 31.60–45.65 U/ml. By using Taguchi design with the inclusion of biosynthesized zinc oxide nanoparticles (ZnONPs), enzyme yield was optimized, achieving 3.47–6.08-fold increase. The ZnONPs having sizes of 9.09–22.02 nm was biosynthesized using aqueous stem bark extract of Cassia fistula. MS emerged as the most efficient substrate, with optimal parameters of inoculum size (2.5 %), fermentation time (96 h), MS concentration (25 g/l), initial pH (12), and ZnONPs concentration (5 µg/ml), leading to a protease yield of 277.50 U/ml. The thermostable and alkaline protease demonstrated promising biomedical and industrial applications, including effective blood stain removal, compatibility with commercial detergents, and moderate thrombolytic activity. This study underscores the dual benefits of valorizing agrowastes while advancing protease production technologies with novel ZnONPs supplementation, paving the way for sustainable industrial applications. Furthermore, the approach aligns with Sustainable Development Goal 9 (Industry, Innovation, and Infrastructure) by fostering increased enzyme production, and promoting industrial innovation for economic growth.