Recovery of plant growth promoting rhizobacteria from sodium alginate beads after three years following storage at 4 ºC

Two plant growth-promoting bacteria, Bacillus subtilis and Pseudomonas corrugata, immobilized in a sodium alginate based formulation were evaluated for their survival, viability and plant growth-promoting ability after 3 years of storage at 4°C. Populations of both of the bacterial isolates recovered from the immobilized sodium alginate beads were in the order of 108 cfu g-1. The plant-based bioassay indicated that the plant growth promotion ability of both of the bacterial isolates was equal to those of fresh broth-based formulations. The bacterial isolates retained the root colonization, and antifungal and enzyme activities in the alginate-based formulation during storage.