Bio-Control of Alternaria alternata during Banana Storage by Purified AFP Using Isoelectric Focusing Technique

Abstract

Interestingly, antifungal protein AFP was purified from Aspergillus giganteus supernatants with modified isoelectric focusing procedure after adaptation of the secretion conditions. Subsequently, the antifungal activity as well as the mode of action against Alternaria alternata was tested in vitro. Moreover, different concentrations of AFP were applied to banana fruits for 15 days at 20˚C in vivo. Obtained results illustrated that A. giganteus was able to secrete about 39.78 ± 2.39 mg AFP∙l−1 Olson medium. The employed ammonium sulfate (AS 75%) precipitation procedure followed by dialysis steps yielded about 16 - 22 mg AFP∙l−1 culture supernatant with general mean of 18.67 ± 1.98 mg∙l−1. The lost amount of AFP during purification using AS and 3KDa cut-off dialysis membrane is about 50% thus, purification procedure must be further improved.