Smart carrier-engineered microbial consortia for precision nutrient delivery in next- generation biofertilizers.

With the increasing demand for sustainable agricultural productivity under a changing climate, the advancement of new-generation biofertilizers specifically based on engineered microbial consortia and smart delivery systems has become an integral part of agricultural activities. The development of next-generation biofertilizers based on engineered microbial consortia and smart delivery systems has emerged as a promising approach for sustainable nutrient management. The drawback associated with conventional microbial inoculants is their inconsistent field performance, which is attributed to the limited viability of microbes under field conditions, environmental factors, and poorly controlled nutrient release. Recent advances in synthetic biology, microbial engineering, and biomaterials have enabled the development of beneficial microbial consortia for agricultural applications. Combining these engineered microbial consortia with advanced carrier technologies, including hydrogels derived from biopolymers, nanomaterials, bio-based polymers, and responsive encapsulation matrices, can enhance microbial protection, controlled delivery, and persistence in soil. The application of methods for encapsulating microorganisms, such as spray drying, ionic gelation, extrusion, and microfluidic encapsulation, can regulate microbial release and may improve microbial survival and rhizosphere colonization. Smart carrier systems are designed to protect microbial cells and regulate their release in response to environmental and plant-associated conditions, thereby supporting more controlled microbial activity and nutrient delivery. This review examines recent developments in engineered microbial consortia, advanced encapsulation techniques, and controlled-release systems for improving nutrient-use efficiency in next-generation biofertilizer formulations.