Development of a soil bioreactor for efficiently degrading organic matter

Abstract

Amylase and protease-producing bacteria isolated from gapi (a traditional fermented Thai food) were used to develop an efficient bioreactor by immobilizing their enzymes with various soils and filter materials. The bioreactor would efficiently degrade excess organic matter originating from overloaded food in culture ponds, thereby improving water quality. Amylase- and protease-producing bacteria were detected in all gapi samples tested. The enzyme extract of gapi was immobilized with soils and filter materials to compare the ability to adsorb these materials. As a result, the amylase and protease adsorption ability significantly differed among the soils and filter materials. In particular, soil collected from Shibecha (Hokkaido) demonstrated a high ability to adsorb amylase and protease of gapi. This ability was possibly ascribed to the high concentration of amorphous aluminum according to an analysis of soil components. Therefore, aluminum oxide was tested as a candidate immobilization carrier for the bioreactor and was found to have high ability to adsorb amylase and protease of gapi as expected. These results suggest that a bioreactor that can efficiently degrade organic matter in culture ponds could be developed by immobilizing gapi enzymes with soils with a high content of amorphous aluminum or pure aluminum oxide.