Production of amylase by fungi isolated from legume seeds collected in Almadinah Almunawwarah, Saudi Arabia

Forty-six fungal species belonging to 26 genera were isolated from 125 legume seed samples on potato dextrose agar at 28 °C. Five types of legumes (broad beans, chickpeas, cowpeas, kidney beans and peas) were investigated for their fungal content. Seed samples (25 for each type of legume) were collected from different localities in Almadinah Almunawwarah, Saudi Arabia. The most prevalent genera were Aspergillus, Emericella, Mucor, Mycosphaerella, Penicillium and Rhizopus. The most common species were Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus ochraceus, Aspergillus terreus, Emericella nidulans, Mucor racemosus, Mycosphaerella tassiana, Penicillium chrysogenum and Rhizopus stolonifer. Broad bean seeds (100%) recorded the highest fungal contamination, followed by cowpeas (88.16%), chickpeas (87.96%), kidney beans (70.41%) and peas (57.75%). Among the 46 fungal species assayed for α-amylase production, eight isolates (17.4% of all isolates) had high amylase activity, 27 (58.7%) had moderate amylase activity, and 11 (23.9%) had low activity. The maximum production of amylase was achieved after 6 days of incubation at 30 °C with an initial pH of 6 and incorporation of starch and ammonium sulphate as carbon and nitrogen sources, respectively.