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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 91, No. 6, 1996
Bioline Code: oc96138
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 91, No. 6, 1996

 en Detection of Extracellular Proteases from Microorganisms on Agar Plates
Alane Beatriz Vermelho; Maria Nazareth Leal Meirelles; Andrea Lopes; Simone Dias Goncalves Petinate; Andre Adriano Chaia & Marta Helena Branquinha

Abstract

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 found 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.

Keywords
protease - detection - microorganism

 
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