Effects of cultivation temperature on alpha-amylase production from wild-type rice callus suspensions

α-Amylase is a key enzyme that hydrolyzes starch into smaller sugars, with applications in food, pharmaceuticals, and biofuels. The objective of this research is to study the effects of cultivation temperature on rice cell growth and the production of α-amylase. Rice callus (Oryza sativa subsp. japonica cv. Nipponbare) suspensions were cultured for 14 days at 140 rpm in 1-L shake flasks under three different temperatures: 27°C, 32°C, and 37°C. Samples were taken and centrifuged to separate spent media (supernatant) and rice callus pellet on days 0, 2, 4, 6, 8, 10, 12, and 14. The α- amylase activity was measured using the DNS (3,5-dinitrosalicylic acid) method. The results indicated that the amount of α-amylase in the spent media was approximately 4–5 times higher than in the cell extract at all three tested temperatures. The optimal conditions for α-amylase activity were found to be at 37°C and pH 7.0.The highest α-amylase activity in the spent media was found at 37°C (1.02 U/ml), significantly higher than those of 32°C (0.90 U/ml) and 27°C (0.86 U/ml), when one unit of enzyme (U) liberates 1.0 mg of maltose from starch in 3 minutes at pH 7.0 and 37°C. During the final days of cultivation, α-amylase is produced to break down stored starch into sugars, compensating for the decreased sugar levels and maintaining energy balance. This approach has the potential to be applied in industry as an alternative for future production processes.