Sustainable Encapsulation of <i>Bacillus velezensis</i> FZB42 Using Tunicate-Derived Carboxymethylcellulose Hydrogels for Enhanced Biocontrol Efficiency

The excessive use of chemical fertilizers and pesticides has led to increasing environmental pollution and biodiversity loss, accelerating the emergence of resistant phytopathogens. As an alternative, biological control agents offer a sustainable approach; however, their efficacy is often limited due to poor stability under varying environmental conditions, underscoring the need for improved formulation strategies. In this study, a pH-responsive hydrogel system was designed by combining tunicate-derived carboxymethylcellulose (TCMC) with alginate to encapsulate spores of the biocontrol bacterium <i>Bacillus velezensis</i> FZB42. The resulting TCMC hydrogel demonstrated controlled spore release under alkaline conditions and enhanced mechanical strength and thermal stability. These properties effectively suppressed alkaline-favoring fungal pathogens, such as <i>Fusarium graminearum</i>, in vitro assays. Beyond its functional performance, the system provides an environmentally conscious solution by repurposing discarded tunicate shells, a major marine waste byproduct. Overall, this platform supports the long-term stabilization and delivery of microbial agents while promoting sustainable agricultural practices and marine biowaste valorization.