Modified loofah sponge-immobilized Mucor circinelloides as efficient and reusable biocatalysts for sustainable biodiesel production

This study developed a novel and efficient biocatalytic system for biodiesel production by immobilizing Mucor circinelloides whole cells on chemically modified loofah sponge. Different functional groups (epoxy, phenyl, benzyl, benzoyl) were introduced onto the loofah sponge surface. Comprehensive characterization (XRD, TGA, UV-Vis, FTIR) confirmed the successful modifications and revealed that epoxy-modified loofah sponge (LSPs-GPTES) emerged as the optimal carrier, demonstrating superior performance. The immobilization rate and catalytic activity of M. circinelloides on LSPs-GPTES reached 150 % and 400 U/g, respectively. When applied to the transesterification of Cornus wilsoniana fruit oil, the LSPs-GPTES-immobilized biocatalyst (LSPs-GPTES-M.CL) achieved an exceptionally high biodiesel yield of 95.9 % under optimized conditions. Most notably, the epoxy modification significantly enhanced the operational stability of the biocatalyst—the most improved property. The LSPs-GPTES-M.CL retained > 70 % of its initial activity after 60 days of storage and maintained effective performance for 10 consecutive reuse cycles, far exceeding the stability of biocatalysts on unmodified or other functionalized carriers. This work highlights the great potential of epoxy-modified loofah sponge as a low-cost, sustainable, and robust carrier for green and efficient biodiesel production. • Novel modified loofah sponge carriers were developed for whole-cell immobilization. • LSPs-GPTES showed excellent immobilization efficiency on Mucor circinelloides . • The biocatalyst retained more lipase activity (>70 %) after 60 days of storage. • LSPs-GPTES-M.CL can be reused for 10 cycles in the production of biodiesel.