Proteolytic and amylolytic potential of fungi from the thermophilic phase of composting

Abstract

Thermophilic microorganisms have proteins that are thermostable and resistant to denaturation and proteolysis. Therefore, the objective of this work was the screening of fungi with amylolytic and proteolytic potential isolated in the thermophilic phase of the composting process of bovine ruminal residue. Samples (500 g) of compost were collected at several points of the six composting strips seven days after the beginning of the process to determine the amount and diversity of microorganisms present during the thermophilic phase of the composting process. After growth, the fungi were inoculated into Petri dishes containing the specific media for amylase and protease production. Cultures were maintained for five days at 30 °C. The diameter of the hydrolysis and colony halos and the Enzyme Index (EI) were evaluated. The fungi 1Q0500, 1Q2506 and 1Q3502 stood out for amylase enzyme production, while for protease enzyme production, the fungi that presented high enzymatic indexes were 1Q1501 (EI = 4.57) and 1Q2506 (EI = 3.06). Fungi isolated from the thermophilic phase of the composting process are satisfactory for proteolytic and amylolytic enzymes production.