Mass Cultivation of Selected Entomopathogenic Microbes

Abstract

Entomopathogenic microbes are organisms that infect insects, mites, and ticks. They are commonly used as biopesticides to control insect populations. This study was designed to evaluate the growth of biocontrol microorganisms on organic biomass without nutrient supplementation, which are byproducts of both domestic and industrial processes. This is to ensure that microbes needed in large amounts, especially for biocontrol or bioremediation processes, can be cheaply cultured, thereby lowering the production costs of commercially available media. Entomopathogenic microbes used in this study include Aspergillus niger, Beauveria bassiana, Metarhizium anisopliae, Bacillus subtilis subspecies spizizenii, Paenibacillus poppiliae, Serratia marcescens, Pseudomonas aeruginosa andLysinibacillus sphaericus. The biomass used includes rice water, spent mash grains, barley powder and maize shaft, which are occasionally used as animal feed supplements and sometimes even discarded as byproducts of domestic and industrial processes. Standard cells of microbes were inoculated into sterilized prepared formulations containing the organic byproducts. Incubation was done at a temperature of 37^OC for 24 hours and 25^OC for 72 hours, respectively, for bacteria and fungi. After the incubation process, B. bassiana grew most on the maize shaft, while A. niger and B. subtilis both had the most growth on spent mash grains. M. anisopliae recorded its lowest value of 2.67×10¹ cfu/ml in maize shaft. The highest microbial count was noticed in B. subtilis (6.67 × 10⁹ cfu/ml) and P. aeruginosa (6.33× 10⁹ cfu/ml) on spent mash grains and barley, respectively.