Abstract:
Alkaline proteases are one of the classes of protease enzymes which are extensively used in
detergent and tanning industries. Currently, there is an increasing demand for biocatalysts
from extreme environments that are important sources of microorganisms routinely used in
novel industrial enzyme production. In this research attempts were made to isolate and screen
for an alternative alkaline protease producing fungal species from abattoir and food wastes.
Hence, fungal species were first isolated from abattoir and food wastes using Potato-Dextrose
Agar. The potential fungal isolates were then identified to the genus level using a combination
of their macroscopic and microscopic morphological features. These isolates were further
screened for alkaline protease production based on their ability to form zone of hydrolysis
(clear-zone) on skim-milk agar media. The potential protease producing fungi were then
subjected to secondary screening using solid-state fermentation. The results indicated that a
total of 7 fungal isolates were able to produce protease during primary and secondary
screening. Out of these, one potential fungal species, the isolate (i.e. S1A2P) that was able to
produce maximum amount of protease was selected for further study based on its proteolytic
activity. This fungal species, isolate S1A2P, was identified to the genus level as Aspergillus
based on its morphological features. Subsequently, its cultural conditions including pH,
temperature, carbon and nitrogen requirements were optimized. The Optimum conditions for
alkaline protease production from S1A2P were found to be 45°C at pH 11.0 with sorghum as
carbon source and casein as nitrogen source. Moreover, studies conducted on alkaline
protease production in the presence of metal ions such as Ca2+, Mg2+and Mn2+ showed
enhanced enzyme activity by S1A2P. Thus on the basis of the above findings, it was concluded
that alkaline protease produced from Aspergillus demonstrated suitable enzyme
characteristics required by the detergent industry and as a result it was recommended for
further evaluation for use as a candidate in detergent production.
