OCHRATOXIN A PRODUCTION IN RELATION TO THE GROWTH-MORPHOLOGY OF ASPERGILLUS-ALUTACEUS

Morphological changes and associated growth kinetics were correlated t o ochratoxin A (OA) production by Aspergillus alutaceus (parent). Two strains (hypo and hyper), isolated following gamma radiation of the pa rent, which differ ed in their ability to synthesize OA relative to th e parent, were investigated The impact of L-glutamic acid (0.5 g/100 m l), a known stimulus for production was also investigated with regards to fungal morphology. Results indicated significant differences betwe en strains in regard ro their hyphal growth emit length (G). The hypo and hyper strains exhibited the highest (184 mu m) and lowest (125 mu m) G, respectively. Addition of L-glutamic acid reduced both the G val ues and the mean tip extension rate for all fungi,. the specific growt h rate, however, remained unchanged Levels of OA were highest (177 mu g/mL) wizen produced by the hyper strain especially in media containin g L-glutamic acid An opposite effect was observed with the hypo strain . Growth rate patterns in terms of leading hyphae and layer al branche s at the colony margins appeared highest fur rite parent at 7 and 14 d ays Inclusion of L-glutamic acid into the growth medium resulted in in creased growth rates for both the parent and strains by day 14. At thi s time maximum growth was achieved by the hyper strain.