Degradation of pectin with probiotic candidate Bacillus subtilis HA1 to oligosaccharides with enhanced anticancer and antioxidant properties

Abstract

Upcycling fruit waste into health-promoting ingredients is an urgent sustainability challenge. In this work, a microbial degradation is described that converts apple pectin into bioactive pectic oligosaccharides (POS) using Bacillus subtilis HA1, a strain isolated from traditional yogurt. HA1 is γ-hemolytic, lecithinase-negative, and free of nhe/hbl enterotoxin genes, yet endures acid/bile and adheres to intestinal cells, confirming its safety and probiotic aptitude. The bacterium cleaves pectin within 6 h of incubation, and under optimum conditions (50 °C, pH 6), the extracellular pectinase showed a maximum activity of ≈18 IU/mL. TLC, LC–ESI–MS, and FTIR verify the formation of low-methylated mono- to tri-galacturonic acids. Crude POS scavenge up to 90 % of DPPH radicals at 10 mg/mL, which is five-fold higher than untreated pectin. POS also act selectively against tumor cells: MCF-7 breast cancer viability drops to 17 %, while healthy L-929 and HUVEC cells remain ≥95 % viable. Flow cytometry and qRT-PCR confirm apoptosis via Bax up-regulation and galectin-3 suppression. Altogether, probiotic candidate strains belonging to the B. subtilis afford a safe, eco-friendly route to high-value POS with potent antioxidant and anticancer activities, opening avenues for functional foods, nutraceuticals, and sustainable pectin valorization.