PRODUCTION OF ALKALINE PROTEASE FROM AVOCADO (Persea americana Mill.) SEED AND PEEL WASTES USING FUNGI

Abstract

Microbial proteases are hydrolytic enzymes that are widely used in many industrial processes. This study aimed to evaluate the production of alkaline protease (AP) from fungal isolates sourced from avocado (Persea americana Mill.) peel (AVP) and avocado seed (AS) under solid state fermentation (SSF). AVP and AS was collocated form Harar juice house into plastic bag and serial diltuion method was used for fungal isolatin. The isolates were subutured on potato dextrose agar (PDA) and AP production was assessed by measuring enzyme activity in the crude enzyme using the spectrophotometric method. A total of five fungal isolates were isolated and identified based on their morphological characterization to the genus level. Skim-milk agar media was used to test fungal isolates for their ability to produce AP. The optimal SSF parameters (pH, temperature, incubation time, and carbon and nitrogen sources) were determined using the one FIctor-at-a-time method. Data were analyzed using SPSS, and statistically significant differences were considered at P<0.05. The result revealed that all five isolates were able to produce AP and the first four isolates (Aspergillus, Fusarium, Rhizopus, and Saccharomyces) were selected for further study based on clear zone diameter formed aroud the colonies. The optimal temperature for AP production was 30°C, with enzyme activities of 87.68 U/ml and 60.77 U/ml for Aspergillus and Saccharomyces.respectively. The maximum enzyme yield was obtained at pH 9.0 for Aspergillus and Fusarium, and 75.525 U/ml for Rhizopus. Relatively, the preferred carbon source was wheat flour, while peptone and yeast extract were relatively good nitrogen sources for AP production. It can be concluded that fungal isolates such as Aspergillus and Rhizopus from AVP and AS were promising candidates in alkaline protease production which is required by different industrial applications. Hence, further molecular identification and characterization of the screened fungal isolates should be conducted to identify them at the species level. The alkaline protease from each isolate should be purified using different methods to increase the enzyme activity.