Agricultural waste upcycling into improved production of triacyl glycerol acyl hydrolases

Abstract

Agricultural waste upcycling is crucial in the context of climate change. Utilizing seven agricultural by-products as basal substrates, coconut meal (Cocos nucifera) emerged as the most efficient, supporting the highest extracellular lipase (triacyl glycerol acyl hydrolases) yield i.e., 5.27 ± 1.75a U mL−1. This study explored the production of extracellular lipases through solid-state fermentation by using co-cultures of Aspergillus niger, wild and mutant strains. Optimization experiments revealed that 30 g of coconut meal resulted is optimal for supporting highest lipases activity of 6.16 ± 0.16a U mL−1. Incubation at 30 °C, 1 mL inoculum size, and distilled water as a diluent further enhanced lipolytic activity. The study identified sucrose as the preferred carbon source, with 4 % concentration demonstrating the highest activity at 13.66 ± 0.33a U mL−1. Supplementary sources like 1 % olive oil and nitrogen sources such as ammonium chloride and peptone significantly increased lipases production. Magnesium sulfate (0.25 %) among metal ions exhibited the highest lipolytic potential i.e., 19.98 ± 0.01a U mL−1. The crude lipases displayed optimal activity at pH 5.0 and 30 °C, with positive effects observed for Fe2+, Ca2+, and Mg2+, while Co2+, Na+, and Hg2+ had negative impacts on lipases activity. This research not only contributes to understanding the factors influencing lipase production and activity, but also serves as an agricultural waste upcycling technique.