Seed Priming with Alginate-Whey Protein Concentrate Encapsulated Bacillus velezensis VRU1 Enhances Growth of...

The development of efficient microbial delivery systems remains a critical challenge in sustainable agriculture. Here, we report the microencapsulation of Bacillus velezensis VRU1, an effective plant growth-promoting bacterium, within an alginate-whey protein concentrate matrix reinforced with carbon nanotubes (CNTs). The strain exhibited multiple PGP traits, including siderophore production, phosphate solubilization, indole-3-acetic acid synthesis (18.7 µg/ml), hydrogen cyanide production, and protease activity. Encapsulation efficiency reached approximately 85%, and release kinetics demonstrated sustained bacterial liberation over 40 days (mean ± SD, n = 3), indicating prolonged availability of viable cells. Under greenhouse conditions, the encapsulated formulation significantly improved several growth parameters and nutrient acquisition in pistachio seedlings, while seed germination percentage and chlorophyll content showed positive but statistically non-significant trends. Controlled release may have contributed to continuous microbial metabolic activity and enhanced nutrient mobilization. Although CNT incorporation was associated with improved root development, future studies should evaluate CNT environmental fate, phytotoxicity, and standalone effects. Overall, this multifunctional encapsulation system improves bacterial stability and delivery efficiency and represents a promising approach for enhancing plant performance under controlled conditions.