Evaluation of Growth Media and Cost-Effective Formulations for Selected Biological Control Agents

Peter Eyegheleme, Tennessee State University


This thesis tackles the vital requirement for disease control agents to sustain agricultural productivity and global food security, with a specific focus on countering Phytophthora capsici (P. capsici), a major threat to vegetable production, especially tomatoes. Current methods predominantly involve chemical fungicides and a limited range of biological control agents.The study extensively assessed three bacterial strains—Bacillus thuringiensis (IMC8), Bacillus subtilis (PRT), and Bacillus amyloliquefaciens (PSL)—known for their non-harmful endophytic colonization of plant tissues. Particularly, PRT demonstrated the highest suppressive effect on P. capsici in in vitro studies. While the greenhouse performance of these bacterial endophytes is detailed elsewhere, this report focuses on field evaluations to validate their potential in managing P. capsici and enhancing tomato yield and quality in the field. Optimal growth media for bacterial yields in spray drying techniques and potential commercial formulations were identified, featuring glucose with yeast extract and molasses with yeast extract. Various carriers were assessed for their impact on BCA viability, with maltodextrin, maltodextrin combined with polyacrylate and gum arabic, and skimmed milk showing the highest BCA viability. The study underscores the importance of efficient drying processes and moisture control in maintaining BCA viability, highlighting a positive correlation between powder recovery and viability. These findings are crucial for enhancing biocontrol efficacy, ensuring commercial viability, and practical utilization in disease management. Additionally, optimizing fermentation media for maximal bacterial endophyte production and the spray drying process are essential steps toward the commercial development of products for effective P. capsici control in field applications.

Subject Area

Agriculture|Plant sciences|Environmental science|Physiology

Recommended Citation

Peter Eyegheleme, "Evaluation of Growth Media and Cost-Effective Formulations for Selected Biological Control Agents" (2023). ETD Collection for Tennessee State University. Paper AAI30692151.