Abstract
One hundred forty-four microorganisms previously isolated from coffee fruit (Coffea arabica) were grown on casein agar to evaluate their proteolytic activities. Fifty percent of filamentous fungi, 52.5% of bacteria and 2.6% of yeasts were able to secrete proteases. Positive isolates were further examined in liquid culture for their protease activities by hydrolysis of casein at different pH values (5.0, 7.0 and 9.0) at 30 o C. Bacillus megaterium, B. subtilis, Enterobacter agglomerans, Kurthia sp, Pseudomonas paucimobilis and Tatumella ptyseos demonstrated the highest proteolytic activities at pH 9.0. One yeast isolate, Citeromyces matritensis, had a proteolytic activity of 2.40 U at pH 5.0. Aspergillus dimorphicus, A. ochraceus, Fusarium moniliforme, F. solani, Penicillium fellutanum and P. waksmanii showed the highest activities. Of the bacterial isolates, the highest enzyme activities were observed in B. subtilis 333 (27.1 U), Tatumella ptyseos (27.0 U) and B. megaterium 817 (26.2 U). Of the filamentous fungi, Aspergillus ochraceus (48.7 U), Fusarium moniliforme 221 (37.5 U) and F. solani 359 (37.4 U) had the highest activities at pH 9.0.
Highlights
Microorganisms are the most common sources of commercial enzymes due to their physiological and biochemical properties, facile culture conditions and ease of cell manipulation
21 (52.5%) out of 40 bacteria strains, one yeast (2.6%) isolate (Citeromyces matritensis) out of 38 strains and 33 (50%) out of 66 strains of filamentous fungi were positive for protease secretion when grown on casein agar
Several Bacillus species isolated from many different environments have been exploited for their alkaline proteases (GUPTA et al, 2002; JOO; CHANG, 2005; KUMAR, 2002)
Summary
Microorganisms are the most common sources of commercial enzymes due to their physiological and biochemical properties, facile culture conditions and ease of cell manipulation. Proteases are the most important for the industry, and constitute approximately 60% of the total industrial enzyme market. These enzymes are used for food processing, pharmaceuticals, leather processing, silver retrieval in the x-ray film industry, industrial waste treatment and as detergent additives. The increasing industrial use of enzymes has led to the need for more specific proteases that can act on some substrates while not interfering with others, and that have defined characteristics for the processes in which they will be used (DIAS et al 2008; GUPTA et al, 2002).
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