ISSN: 2471-9315
Rex Ogbonnaya Ogbonnaya, O K Achi and U N Ekwenye
Federal University Ndufu-Alike Ikwo, Nigeria
Michael Okpara University of Agriculture, Nigeria
Scientific Tracks Abstracts: Appli Micro Open Access
The aim of this study was to evaluate the effect of addition of freeze-drying protective substances (Sucrose 10%, glucose 10%, fructose 10%, lactose 10%, skimmed milk 10%) or their combinations (Sucrose 10%+Skimmed milk 10%, glucose 10%+Skimmed milk 10%, fructose 10%+Skimmed milk 10%, lactose 10%+Skimmed milk) and different rehydration media (water, 10% NFSM, phosphate buffer) on the viability and storage stability of Bacillus cereus and Candida xestobii freeze-dried cells for biocontrol of green-mold disease of stored Sorghum grains caused by Aspergillus flavus. Candida xestobii and Bacillus mycoides strains were previously isolated from non-diseased stored Sorghum grains. Several concentrations of protective agents and rehydration media were added separately during freeze-drying to determine tolerance and survival rate of Candida xestobii and Bacillus mycoides strains after freeze-drying. The survival rate after rehydration and during storage of freeze-dried strains was evaluated. The results indicated significant decrease in viability of Candida xestobii and Bacillus mycoides freeze-dried cells. Addition of Sucrose 10%+Skimmed milk 10% and sucrose 10% as freeze-drying protectants significantly increased the survival rate of Candida xestobii and Bacilllus mycoides (p<0.05) and rehydration with water provided a better recovery of freeze-dried Candida xestobii than Bacillus mycoides cells. Rehydration with Skimmed milk 10% conferred higher cell viability for Bacillus mycoides. In subsequent storage, B. mycoides and Candida xestobii cells shelf life was maintained during 30 days when stored at 4 oC (96-86%) and decreased significantly from 96-24% at 22�?±1 oC over a period of 120 days. This study has shown that shock tolerance, survival and cell stability of B. mycoides and C. xestobii strains could be improved during freeze-drying by use of freeze-drying protectants, rehydration media and storage temperature during formulation process of these antagonistic strains for eventual post-harvest application.
Rex Ogbonnaya Ogbonnaya has obtained his PhD in Industrial Microbiology & Biotechnology in 2014 from Michael Okpara University of Agriculture, Nigeria and has since then working as a Lecturer at the Department of Biolog, Microbiology, Biotechnology at the Federal University Ndufu Alike-Ikwo, Ebonyi state, Nigeria. He was the Director of Quality Assurance & Control in Petsow Laboratories Limited (former Petsow Integra), a fore-front Pharmaceutical Industry in Nigeria and subsidiary of Starline Conglomerate for several years. He has published a number of papers in reputed journals.
Email: rexogbz@yahoo.com