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Curr Microbiol (2008) 57:503507
DOI 10.1007/s00284-008-9276-8
A Rapid and Easy Method for the Detection of Microbial Cellulases on Agar Plates Using Grams Iodine
Ramesh Chand Kasana Richa Salwan Hena Dhar Som Dutt Arvind Gulati
Received: 15 May 2008 / Accepted: 30 June 2008 / Published online: 23 September 2008 Springer Science+Business Media, LLC 2008
Abstract Screening for cellulase-producing microorganisms is routinely done on carboxymethylcellulose (CMC) plates. The culture plates are ooded either with 1% hexadecyltrimethyl ammonium bromide or with 0.1% Congo red followed by 1 M NaCl. In both cases, it takes a minimum of 30 to 40 minutes to obtain the zone of hydrolysis after ooding, and the hydrolyzed area is not sharply discernible. An improved method is reported herein for the detection of extracellular cellulase production by micro-organisms by way of plate assay. In this method, CMC plates were ooded with Grams iodine instead of the reagents just mentioned. Grams iodine formed a bluish-black complex with cellulose but not with hydrolyzed cellulose, giving a sharp and distinct zone around the cellulase-producing microbial colonies within 3 to 5 minutes. The new method is rapid and efcient; therefore, it can be easily performed for screening large numbers of microbial cultures of both bacteria and fungi. This is the rst report on the use of Grams iodine for the detection of cellulase production by microorganisms using plate assay.
Introduction
The term cellulases refers to a group of enzymes that catalyze the hydrolysis of cellulose into sugars. Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants [1]. Cellulolytic enzymes from
microorganisms also have many potential biotechnologic and industrial applications. Cellulases are required in large quantities because of their application in many industries, such as textiles, detergent, food, animal feed, bio-fuel, paper and pulp, pharmaceutical, and waste management [25, 8, 11, 12]. The rst step in the development of an industrial process for the production of an enzyme is to isolate the potential strains. Isolation and screening of microbes for cellulases is of immense importance keeping in view the demand for new enzymes and the improvement of their biotechnologic applications. An easy, fast, and environmentally friendly qualitative method is described for screening microorganisms producing extracellular cellulase on...