ELISA OPTIMISATION FOR MONITORING BACILLUS SUBTILIS IN PREHARVEST BIOCONTROL PROGRAMMES

Abstract Enzyme linked immunosorbent assay (ELISA) was optimised for more effective monitoring of Bacillus subtilis in avocado field spray programmes using natural antagonists. Parameters of the ELISA that were optimised included, incubation temperature and -time, fixatives, blocking buffers, washing buffers, antibody incubation time, conjugate concentration, conjugate incubation time and enzyme-substrate reaction time. Incubation conditions of 4ºC for 24 h gave the highest signal/background value, the baking method was found more applicable due to its 3 months storage potential without loss of ELISA signals. Bovine serum albumin gave the highest signals when used as a blocking solution. When comparing the optimised ELISA protocol with the one used previously, a higher signal/ background value were obtained with the former ELISA