Effect of low power microwave on microbial growth, enzyme activity, and aflatoxin production

This study aimed at investigating the effect of low power (90 W) microwave radiation(2450 MHz) on microbial growth, enzyme activity (protease and urease), and aflatoxinproduction. Thermal effect was avoided by keeping inoculum in ice while treating withmicrowave (for varying duration i.e. 2, 4, and 6 min). After 6 min MW treatment to S. aureus,its growth was stimulated over control by ~10%. Total protease activity in Aeromonashydrophila witnessed a 33% decrease as compared to control after a microwave exposure of 2min. Similar decrease of 24% in total protease activity of Candida albicans was observed aftermicrowave exposure of 6 min. Staphylococcus aureus lost its urease activity completely aftermicrowave treatment. Aflatoxin production was completely inhibited in Aspergillusparasiticus after microwave exposure of 2, 4, and 6 min. However, it required a 6 minmicrowave exposure for complete inhibition of aflatoxin production in Aspergillus flavus.Our results positively suggest existence of microwave specific non-thermal effect onmicrobial growth and metabolism.