Starch is an accessible source of energy for microorganisms. Microbial amylolytic enzymes contribute to starch degradation. The genus Rhizopus fungi is known to be great producers for amylolytic enzymes. Amylase from Rhizopus species has been used for various industrial applications. This study was carried out to detect starch-degrading ability of Rhizopus azygosporus UICC 539 on 1 % (w/v) and 2 % (w/v) commercial starch at various temperatures. Agar block (diameter 6 mm) containing a concentration of R. azygosporus cells at approximately 106 cell/mL was prepared from a 5-day old fungus in Potato Sucrose Agar (PSA) at 30 °C. The agar block was inoculated on the modified Czapek’s Dox Agar (CDA) plates without a carbon source, and 1 % (w/v) or 2 % (w/v) commercial starch was incorporated to serve as the only carbon source. The CDA plates were incubated for 3 days and 5 days at various temperatures (30 °C, 35 °C, 40 °C, 45 °C and 50 °C). The modified CDA plates without the fungus served as control. Starch-degrading enzyme activity was observed after day-3 and day-5 of incubation. Clear zones were indicative for starch hydrolysis and Lugol’s iodine was used as an indicator. Enzymatic Index (EI) was determined based on the given formula: R/r, where R was the diameter of the entire clear zone, and r was the diameter of the fungal colony. The results showed that starch-degrading ability of R. azygosporus UICC 539 was detected at both starch concentrations and at all tested temperatures. High EI was observed at 50 °C in both concentrations of starch, with the highest EI on 1 % starch after day-5 of incubation. In conclusion R. azygosporus UICC 539 has the starch-degrading ability to degrade 1% and 2 % starch in the temperature range of 30–50 °C and produced clear zones, which was indicative that this strain secreted amylolytic enzyme (amylase) into the medium. This study indicated that R. azygosporus UICC 539 was a potential candidate for fermentation of starch- containing agricultural byproducts.

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