Heterogeneous biocatalysts based on porous polymer and lipase from Aspergillus niger obtained from SSC employing agroindustrial residues as raw material

This study aimed to produce extracellular lipases from Aspergillus niger using solid-state cultivation (SSC) of cottonseed bran and a blend of cottonseed bran and wheat bran (agroindustrial coproducts) as low-cost substrates. The highest activity (93.1 U/g dry mass ) was achieved with cottonseed bran supplemented with castor oil at a moisture content of 54%. A mesoporous poly(styrene-co-divinylbenzene) (poly(Sty-co-DVB)) support (surface area of 259 m 2 g −1 ) was used for lipase immobilization. The immobilization yield ranged from 67.3% to 98.2%, whereas the biocatalyst's Ra was much lower, ranging from 5 to 30%. The heterogeneous biocatalysts were evaluated for the hydrolysis of castor oil, achieving ester-to-free fatty acid conversions ranging from 17.7% to 45%. Their performance was compared with that of commercial immobilized lipases (Lipozyme TL, Lipozyme RM, and Lipozyme 435). The SSC-derived biocatalysts showed activity comparable to the commercial ones. Furthermore, the heterogeneous biocatalyst maintained its catalytic efficiency over five consecutive hydrolysis reactions, with no significant decrease in conversion. Overall, this study demonstrates the feasibility of using agro-industrial by-products as inexpensive substrates for lipase production and highlights the potential of SSC-derived immobilized biocatalysts as sustainable, cost-effective alternatives for enzymatic hydrolysis.