Production of bioactive nutraceuticals from autoclave and surface sterilized fish skin waste using microbial fermentation

Abstract

The fish processing industry generates substantial by-products, including viscera, heads, scales, and bones, which pose environmental challenges if not managed properly. This study explores the potential of fish skin waste from Carangoides malabaricus (Malabar Kingfish/Trevally/Parai) for bioactive compound production through microbial fermentation using Aspergillus oryzae, Bacillus subtilis, and Saccharomyces cerevisiae. Fish skin was pretreated via autoclaving and surface sterilization before controlled fermentation. The resulting extracts were analyzed for phytochemical constituents and evaluated for antioxidant, anti-inflammatory, antimicrobial, and anticancer properties.The extracts contained bioactive compounds such as alkaloids, phenols, terpenoids, carbohydrates, and proteins. Among surface-sterilized samples, Saccharomyces cerevisiae fermentation produced the highest protein content, while Aspergillus oryzae extracts from autoclaved samples showed the strongest antioxidant activity. The Aspergillus oryzae fermented autoclaved sample also exhibited excellent anti-inflammatory effects. Bacillus subtilis extracts demonstrated antibacterial activity against E. coli, B. cereus, Staphylococcus, and Klebsiella species, along with moderate antifungal activity. Additionally, both Saccharomyces cerevisiae and Bacillus subtilis extracts displayed strong anticancer activity.This study highlights fish skin waste as a sustainable source of bioactive compounds, contributing to waste valorization, environmental sustainability, and potential pharmaceutical applications.