Production of microbial lipase in culture media using fish waste as a substrate source

This study focuses on a sustainable approach aimed at converting waste generated in fish processing plants into high-value products. The main objective of this research is to evaluate these protein- and fat-rich wastes as a substrate source for microbial lipase production and to determine the most suitable culture medium conditions. This study presents the potential for cost-effectiveness and environmental benefits in industrial enzyme production. The research methodology is based on the fermentation of Bacillus licheniformis, a known lipase-producing microorganism, in culture media with varying concentrations of fish waste and glucose. The effects of factors such as fish waste (5%, 7.5%, 10%, 15%, 20%), glucose (1%, 2.5%, 5%), and incubation time (24, 48, 72 hours) on enzyme activity were systematically investigated. The data collection process involved measuring lipase activity using a titrimetric analysis method on samples taken from the culture media at specified time intervals. A versatile approach was adopted for data analysis. While descriptive statistics provided average, minimum, and maximum lipase activity values under different conditions, analysis of variance (ANOVA) evaluated the individual and interactive effects of the independent variables on enzyme activity. Pearson correlation analysis was applied to understand the strength of relationships between variables, and multiple regression analysis was used to identify the factors that best explain enzyme activity. According to the findings, increasing fish waste and glucose concentrations tended to increase lipase activity. The highest enzyme activity was observed in specific combinations, such as 10–15% fish waste and 5% glucose, and at a 48- hour incubation time. The ANOVA results showed that all factors and their interactions, especially fish waste percentage and glucose concentration, had a statistically significant effect on lipase activity. Regression analysis results indicated that glucose and fish waste concentrations were the variables that most strongly affected lipase activity, and the developed model had a high explanatory power (R2=0.91). Enzyme stability analyses pointed to the high stability of the produced lipase in the temperature range of 35–45°C and pH 6–8. In conclusion, this study demonstrates that fish waste can be used as a valuable substrate source for microbial lipase production and provides important reference data for determining the most suitable production conditions. These findings are expected to provide a basis for future studies on the biotechnological valorization of seafood waste. Keywords: Alkaline Protease, Lipase, Microbial Production, Optimization