Fiber fractions from processing of barley in production and conservation of a biologic control agent

Carriers are frequently used to overcome problems associated with microbial survival in soil after inoculation. Moreover, the use of carriers can prolong the shelf lives and lessen dusting of both biofungicides and biologic fertilizers. This study investigated the suitability of barley-based fiber fractions as growth media and immobilization matrices in the cultivation of a Streptomyces griseoviridis biologic control agent, as well as for the conservation of obtained biomass in dehydrated hydrogel capsules. The second main ingredient in all the examined carrier matrices was alginate. The aim was to find a hydrogel formulation suited for a production process in which all individual steps, including cultivation of the organism; downstream processing; and formulation, storage, and application of the product (i.e., biologic control agent), are carried out in the hydrogel matrix. Of the tested fractions, brewer’s spent grain was the best choice, when considering the price vs the nutrient contents as well as the storage time and ease of processing of the crude and the finished products. It seems that cereal fibers can be replenished with cereal fractions less rich in fiber but having a higher content of utilizable nutrients and, hence, better suited for the production of biomass. A high content of water-insoluble fiber favorably influenced the appearance as well as the applicability of the products.