Shelf-life enhancement of bio-inoculants through synergistic effects of encapsulation technology and osmotic protectants

A novel protective capsule for encapsulating microorganism inoculants was developed based on a core/shell structured hydrogel doped with osmotic regulators, with the aim of protecting against salts stress. The resulting capsules showed favorable mechanical toughness, high encapsulated efficiency, low cell leakage and increased resistance against salt attack. Different types of sugar alcohol molecules were selected as the osmoprotectants and their effectiveness in retaining the microbial count of trichoderma harziana under adverse conditions was examined. It was found that by using trehalose-doped core/shell structured hydrogels as the microbial carrier, the survival rate and mycelial growth rate of trichoderma harziana increased during incubation in sodium chloride solution and on sodium chloride-containing solid medium. Furthermore, the shelf-life of the microor-ganisms demonstrated a significant increase from log 5.72 cfu/g to log 7.30 cfu/g after an incubation period of 180 days in compound fertilizers with 15 % nitrogen-phosphorus-potassium (NPK) content. This novel microbial encapsulated system showed remarkable preservation of microorganism inoculants under salt stress from fer-tilizer nutrients, suggesting a noticeable practical potential in agriculture.