Encapsulating Nitrogen-Fixing Bacteria for Microbial Fertilizers — 37p — Johnathan Orosz, Volker Brozel

The encapsulation of plant growth-promoting bacteria in organic polymer (sic biofertilizer) may provide alternatives to synthetic fertilizers, which can have negative environmental side effects.  Inspired by nature, this technology is in its simplest form a temporary shelter for microbes, which can be made, stored, and then applied to agricultural soils as a fertilizer.  These ~0.5mm diameter shelters are delivery systems for viable bacteria.  We aim to optimize the application of encapsulated diazotrophic bacteria with the goals of creating a product that can be made and stored at low cost to farmers and which consistently correlates with crop yields on par with those grown with current synthetic fertilizer.  The process of creating alginate beads, the organic polymer, is well established.  We have modified old methods of encapsulating bacteria which can then be sown with seed.  One obstacle to deployment of plant growth-promoting microbes are cost-effective techniques to keep cells viable.  We experimented with different formulations of gel matrix and drying methods, based on literature, to optimize cell survival for the diazotroph Stutzerimonas stutzeri.  We found that the addition of gellan gum to the alginate-based gel matrix improved cell survival regardless of drying method.  Drying method did not significantly affect survival.  Encapsulated cells survive for more than 60 days without significant decrease in viable cells.

South Dakota State University
Volker Brozel