Amylase activity of amylolytic bacteria from black soldier fly (Hermetia illucens)

Abstract

Amylase is an enzyme that has been widely used as a biocatalyst in food and bioethanol industries. The availability of thermostable amylase will further expand the market and extend the shelf life of this enzyme. Amylase is produced by amylolytic bacteria using media with high-cost nitrogen sources, such as pepton. Black soldier fly (BSF) is a potential source of amylolitic bacteria since its ability to degrade organic matters rapidly. This research aimed to explore amylolitic bacteria from the larvae of BSF with highest amylase activity that can be produced using low-cost media. The screening of amylase activity was conducted by culturing the bacteria on starch containing media. Bacteria with the highest amylase activity were cultured in liquid media with two different nitrogen sources (urea and nitrate). Determinations of the optimum pH and temperature for this enzyme activity were carried out in the pH range 4 to 7 and temperature 35 to 65 ºC. Three amylase-producing isolates were obtained in this study. M1 isolate which has the highest activity was characterized based on catalase activity and Gram staining. The results showed that the M1 isolate might belong to genus Proteus sp. At the optimum condition (45 ºC and pH 7), amylase activity in nitrate media was 0.791 U/mL, which was about 18-folds higher than that in urea media (0,041 U/mL). Thus, amylase isolated from BSF larvae can be classified as a mesophilic enzyme and has the potential to be developed commercially at lower production costs.

Keywords

• crude extract enzyme
• proteus sp.
• thermostable