Exploration of Moulds for Extracellular Protease Production

Abstract

Protease enzymes carry a domineering status because of their wide scale applications in the fabric upgrading, food processing, dairy, leather, waste  management, detergent and allied industries. They account for more than 60 % of total global enzyme sales. Mould isolates from samples of soil, food  and Winogradsky column were screened for extracellular protease production. The filamentous fungi were isolated and purified by sub-culturing on  potato dextrose agar. The spore forming unit (SFU) of the moulds per gram of the sample ranged from 1.0 × 102 (log 4.00) to 5 × 104 (log 5.70) for raw  onion and raw meat, respectively. The moulds recovered were Aspergillus niger, A. fumigatus, as well as species of Mucor, Penicillium and Rhizopus. The  pure isolates were subjected to protease screening on skim milk agar to determine their proteolytic activity and the enzyme appears to be ubiquitous in  all the isolates. Aspergillus niger strain BM-1which was isolated from beef ‘suya’, produced the highest zone of proteolysis (73 ± 10 SED), on SMA at 28o C  for four days. A species of Rhizopus was the least proteolytic isolate (30 ± 0.0 SED) while other proteolytic isolates were species of Penicillium and Mucor.  Filamentous fungi could serve as principal producers of protease enzymes for large scale industrial production and commercial exploitation.