Microencapsulated formulation of rhizobacteria Bacillus cereus C1L and application in fungal disease control
Date Issued
2008
Date
2008
Author(s)
Lin, Yu-Chun
Abstract
Corn components can be found in thousands of products. However, maize diseases create significant problems for the maize grower. Diseases reduce yield potential, alter normal maturity and reduce grain quality. These factors slow harvest and increase field loss. Recently, a novel gram-positive strictly aerobic, motile sporulating bacterium was isolated from a soil sample and identified as a Bacillus cereus C1L. The strain presented remarkable activity to inhibit the growth of fungus. Thus, the purpose of this study was to formulate a new biopesticide using microencapsulation to provide protection from extreme environmental conditions and enhanced residual stability due to slow release of formulations. In addition, viable cell number of Bacillus cereus C1L is an important factor. For create a new pesticide, this study also optimized the best formula for maximum viability of Bacillus cereus C1L using response surface methodology（RSM）and sequential quadratic programming（SQP）method when subjected to a spray-drying process. At the same time, the cost-effective materials regards as media in scale-up fermentation were also evaluated. Results of growth medium formulation indicated that the cell numbers of Bacillus cereus C1L could be reached to 109cfu/mL and cultivation cost could be down to 0.7 NTD / kg when sugar yeast powder was used as the nitrogen source. urther encapsulation of this bacterium by spray drying and extrusion found that spray drying with corn starch showing the best plant induced resistance. Optimization results revealed that the strain could maintain 0.42 % viability when adding 18.3% corn starch and inlet temperature at 73.5 ℃. The verification experiment yielded a result close to the predicted values with similar performance. By comparing with chemical pesticide, results indicated that chemical pesticide Menbe showed the best efficiency of disease inhibition, following was B. cereus C1L encapuslation by spray drying. Chemical pesticide Probenazole and B. cereus C1L encapuslation by extrustion revealed no significant difference in disease control. In conclusion, we successfully formulate a new biopesticide with B. cereus C1L using microencapsulation to provide protection with cost-effective materials and high activity. In the future, the field test needs to investigate to prove that this biopesticide might provide a good solution for the best protection against fungus for maize grower.
Subjects
bacillus cereus C1L
microencapsulation
biocontrol
Type
thesis
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