Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/29/2001
Publication Date: N/A
Technical Abstract: Gibberella zeae is the primary causal agent of Fusarium head blight (FHB) of wheat. Cryptococcus sp. OH 181.1 and C. nodaensis OH 182.9 have reduced FHB severity on several types of wheat in multiple field tests. In shake flask experiments, increasing total carbon and nitrogen loading by one half in a semidefined medium (SDM) was not effective in increasing CFU production for either strain. Log phase precultures of each antagonist were used to inoculate a B Braun D-30 bioreactor charged with 20 liters of 1X SDM. Cells were harvested after 48 h using a Sharples tubular bowl centrifuge, resuspended to 1/5 original volume using buffer or spent broth and frozen at -18 C. Cultures reached stationary phase after 35-40 h when dissolved O(2) returned to near 100%. Preharvest yields were 4 x 10(8) CFU/ml to 1 x 10(9) CFU/ml for OH 181.1 and OH 182.9, respectively. Less than 2% of viable biomass was lost during harvesting. After 14 days of frozen storage, buffer resuspended cells maintained higher CFU/ml than cells resuspended in spent broth though biocontrol efficacy was similar.