An Exploratory Approach to Sustainable Esterase Production Through Co-Valorization of Cheese Whey and Vegetable Wax for Supported Solid-State Fermentation by Serratia marcescens 11E

Lipolytic and esterase-like enzymes are crucial in the food industry for flavor production and ester hydrolysis. This study presents an exploratory, baseline feasibility approach to evaluate esterase-like enzyme production by Serratia marcescens 11E via a sustainable co-valorization matrix, where vegetable wax residues serve as structural solid support and cheese whey acts as the primary lipid nutritional source. Under fixed 48-h screening conditions, the recovered cell-free extract exhibited a distinct catalytic preference for short-chain esters, showing higher specific activity toward 4-nitrophenyl acetate (0.743 U/mg) than 4-nitrophenyl palmitate (0.125 U/mg), confirming a predominant carboxylesterase-like profile. Biochemical characterization revealed an initial optimal activity at pH 9.0 and 30 °C, along with a noteworthy bimodal catalytic behavior featuring a secondary activity peak at 70 °C. Size-exclusion chromatography resolved the extract into two distinct active elution pools (17.8 and 26.2 U/mg), which corresponded to candidate protein bands of 35–40 kDa on SDS-PAGE. Although definitive molecular identification remains subject to ongoing zymographic and proteomic characterization, these foundational findings demonstrate the potential of co-valorizing lipid- and carbohydrate-rich industrial wastes to produce resilient proteins with esterase-like activity at elevated temperatures.