Amylases are a group of commercially important enzymes with various clinical, medical and biotechnological applications. The current study aims to optimize the agitation and aeration (oxygen transfer) conditions for α-amylase production by Aspergillus flavus using water hyacinth extract; as an available waste and very cheap nutritional substance, in a lab scale stirred tank bioreactor (submerged fermentation). Data showed that the maximal cell biomass and enzyme specific activity were reached at low aeration rate (0.5 v/v/m) and moderate agitation speed (200 rpm). The maximum specific amylase production rate has been reached after 24 hrs. In addition, it has been confirmed that scaling-up Aspergillus flavus does not, inversely, affect α-amylase productivity compared with flask level production. Aspergillus flavus has been approved as promising fungal isolate for production of a-amylase using water hyacinth for application in many fields.

Some environmental and nutritional parameters controlling the biosynthesis of α-amylase from Aspergillus flavus, F7 attacking the water hyacinth have been investigated under solid state fermentation conditions for maximum amylase production. The following optima’s were recorded for the highest α-amylase yield; Incubation period 7 days; temperature, 30oC; pH, 5; inoculum size, 3X108 spores/ml; flask volume 100 ml capacity; hyacinth fresh weight 5 g; tap water, 25 ml. Under these conditions, starch showed remarkable stimulatory effect; nitrogen sources and amino acids have no stimulatory effect. Pyridoxal hydrochloride, B6 at a concentration of 200 ppm exhibited a stimulatory effect on biosynthesis of α-amylase.