A rapid, efficient and sensitive plate assay for detection and screening of l-asparaginase-producing microorganisms

Abstract l-Asparaginase-producing microbes are conventionally screened on phenol red l-asparagine-containing plates. However, sometimes the contrast of the zone obtained (between yellow and pink) is not very sharp and distinct. In the present investigation, an improved method for screening of the mi...

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Bibliographic Details
Published in:FEMS microbiology letters 2013-04, Vol.341 (2), p.122-126
Main Authors: Mahajan, Richi V., Saran, Saurabh, Saxena, Rajendra K., Srivastava, Ayush K.
Format: Article
Language:English
Subjects:
Asparaginase - analysis
Asparaginase - metabolism
Bacteria - enzymology
Bacteria - genetics
Bacteria - isolation & purification
Bacterial Proteins - analysis
Bacterial Proteins - metabolism
Biological and medical sciences
bromothymol blue
Colonies
Culture Media - chemistry
Enzyme Assays - instrumentation
Enzyme Assays - methods
Fundamental and applied biological sciences. Psychology
l‐asparaginase, screening
Microbiology
phenol red
Phenols
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Summary:Abstract l-Asparaginase-producing microbes are conventionally screened on phenol red l-asparagine-containing plates. However, sometimes the contrast of the zone obtained (between yellow and pink) is not very sharp and distinct. In the present investigation, an improved method for screening of the microorganisms producing extracellular l-asparaginase is reported wherein bromothymol blue (BTB) is incorporated as pH indicator in l-asparagine-containing medium instead of phenol red. Plates containing BTB at acidic pH are yellow and turn dark blue at alkaline pH. Thus, a dense dark blue zone is formed around microbial colonies producing l-asparaginase, differentiating between enzyme producers and non-producers. The present method is more sensitive and accurate than the conventional method for screening of both fungi and bacteria producing extracellular l-asparaginase. Furthermore, BTB gives a transient green colour at neutral pH (7.0) and dark blue colour at higher pH 8.0–9.0, indicating the potency of the microorganism for l-asparaginase production.
ISSN:0378-1097
1574-6968
DOI:10.1111/1574-6968.12100