ENZYMATIC-ACTIVITY AND MYCOTOXIN-PRODUCING POTENTIAL OF FUNGI ISOLATED FROM ROTTED LEMONS

Nine species related to seven genera were recovered from rotting lemon (Citrus limon Syn.) fruits. Alternaria alternata appeared to be the m ain causer of lemon rot followed by Aspergillus flavus and A. niger. F rom the isolated fungi, 37 isolates were screened for their ability to produce some enzymes on solid media. Data clearly showed that not all the tested isolates were only able to produce cellulase but most of t hem were also good producers of this enzyme.In addition to cellulase, pectin lyase (PL) and poly-galacturonase (PG) production were also ver ified by many of these isolates. During screening for mycotoxigenicity of the isolated fungi on liquid medium, 17 out of 43 isolates were to xigenic. Alternaria alternata produced alternariol (AOH) and alternari ol monomethyl ether (AME) and A. flavus produced aflatoxins B1 and B2. Alternaria toxins and aflatoxins B1 and B2 were also produced in heal thy lemon fruits infected with toxigenic isolates of Alternaria altern ata and A. flavus, respectively. The presence of these mycotoxins in i nfected lemons may constitute a potential hazard to human health.