Detection of extracellular proteases from microorganisms on agar plates

Alane Beatriz Vermelho, Maria Nazareth Leal Meirelles, Andréa Lopes, Simone Dias Gonçalves Petinate, André Adriano Chaia, Marta Helena Branquinha
1996 Memórias do Instituto Oswaldo Cruz  
We present herein an improved assay for detecting the presence of extracellular proteases from microorganisms on agar plates. Using different substrates (gelatin, BSA, hemoglobin) incorporated into the agar and varying the culture medium composition, we were able to detect proteolytic activities from Pseudomonas aeruginosa, Micrococcus luteus and Serratia marcescens as well as the influence that these components displayed in the expression of these enzymes. For all microorganisms tested we
more » ... that in agar-BHI or yeast extract medium containing gelatin the sensitivity of proteinase detection was considerably greater than in BSA-agar or hemoglobin-agar. However, when BSA or hemoglobin were added to the culture medium, there was an increase in growth along with a marked reduction in the amount of proteinase production. In the case of M. luteus the incorporation of glycerol in BHI or yeast extract gelatin-agar induced protease liberation. Our results indicate that the technique described here is of value for detecting extracellular proteases directly in the culture medium, by means of a qualitative assay, simple, inexpensive, straight forward method to assess the presence of the proteolytic activity of a given microorganism colony with great freedom in substrate selection.
doi:10.1590/s0074-02761996000600020 pmid:9283660 fatcat:vpjc2zau7jflbnnsuu7b6w7wrq