Antagonistic Efficiency of Aspergillus giganteus as a Biocontrol Agent against Aflatoxigenic Aspergillus flavus Infecting Maize

Aspergillus flavus is a fungal pathogen which infects maize crops and produces aflatoxin thus bringing about huge losses in crop production. Developing biocontrol agents against Aspergillus flavus has been the best strategy for the control of contamination in the fields. The aim of this study was to evaluate the biocontrol potential of Aspergillus giganteus against A. flavus by in vitro coculture studies. The effect of antagonism was studied by varying the carbon and nitrogen sources and under different interacting conditions of pH, temperature and water activities. The conidia production by A. flavus during coculture conditions favourable for antagonism was also assessed. A significantly notable growth inhibition of about 86.1% was brought about by A. giganteus in the coculture, which surrounded the mycelia of pathogenic A. flavus, arresting its growth. A maximum inhibition of 86.1% was observed when sucrose was used as the carbon source and a significantly higher inhibition of 90.93% was seen when beef extract was used as the nitrogen source. Among the different temperatures tested, the highest inhibition was observed at 30°C which was 87.43%. An increasing trend in the inhibitions were seen with decrease in pH and water activity (aw), where, the highest inhibition was 89.75% for pH 6.0 and 94.03% for aw 0.846. Drastic reductions in conidial number and halting of sclerotia production was observed in coculture clearly suggesting that A. giganteus will serve to be a potent and promising biocontrol strain under different environmental conditions.