Hindawi Publishing Corporation Journal of Mycology Volume 2013, Article ID 753692, 7 pages http://dx.doi.org/10.1155/2013/753692 Research Article Tetrazolium/Formazan Test as an Efficient Method to Determine Fungal Chitosan Antimicrobial Activity Shaaban H. Moussa, 1,2 Ahmed A. Tayel, 1 Ahmed A. Al-Hassan, 3 and A. Farouk 4 1 Genetic Engineering and Biotechnology Research Institute, Minouiya University, El-Sadat City, P.O. Box 79/22857, Egypt 2 he Promising Research Center in Biological Control and Agricultural Information, the University of Qassim, P.O. Box 6622, Buraydah 51452, Saudi Arabia 3 Department of Food Science & Human Nutrition, College of Agriculture & Veterinary Medicine, Qassim University, P.O. Box 6622, Buraydah 51452, Saudi Arabia 4 National Research Center, Textile Division, Textile Chemistry and Technology, Department of Preparation and Finishing of Cellulosic Fibers, Tahrir Street, Dokki, P.O. Box 12622, Giza, Egypt Correspondence should be addressed to Shaaban H. Moussa; shaus2008@yahoo.com Received 8 March 2013; Revised 13 May 2013; Accepted 13 May 2013 Academic Editor: Zia U. Khan Copyright © 2013 Shaaban H. Moussa et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fungal chitosan was extracted from Aspergillus niger mycelia. he produced chitosan was characterized with deacetylation degree of 89.2%, a molecular weight of 2.4 × 10 4 Da, and 96.0% solubility in 1% acetic acid solution. he antibacterial activity of fungal chitosan was evaluated against two foodborne pathogens, that is, Salmonella typhimurium and Staphylococcus aureus, using the established antibacterial assays, for example, zone of growth inhibition and agar plat count tests, and using 2,3,5,-triphenyltetrazolium chloride (TTC) as chromogenic marker for qualitative and quantitative determining of antibacterial potentiality. he TTC (0.5% w/v) was added, at concentration of 10%, to cultured broth, containing chitosan with diferent concentrations then the formed formazan was separated. he formation of red formazan could be considered as a qualitative indication for antibacterial activity, whereas the measurement of color intensity for the resuspended red formazan, using spectrophotometer at 480 nm, provided a quantitative evidence for the strength of the used antibacterial agent. Regarding the rapidity, technical simplicity, and cost-efectiveness, TTC assay could be recommended as an eicient alternative method for qualitative and quantitative determination of chitosan antibacterial activity and could be suggested for general evaluation of antibacterial agents. 1. Introduction Chitosan is a cationic polysaccharide consisted of many mon- osaccharide units of -(1,4) linked 2-amino-2-deoxy-D-glu- copyranose. he innocuous biodegradable and bioeffective nature of chitosan recommends its use in many ields of biotechnology, food industry, cosmetology, agriculture, and phar-macology [1–3]. Chitosan can be extracted from the cell wall of fungi, particularly zygomycetes. he production of chitosan from fungal cell walls has many advantages such as independence of seasonal factor and wide-scale production. he extraction process is more simple and cheap resulting in a reduction in time and cost required for production [4]. he antimicrobial materials are widely used in indus- try, community, and private settings to prevent microbial infection and contamination. To obtain biocidal efect with- out releasing biocides into the environment, natural antimi- crobials, like chitosan, are highly recommended to be applied. he antimicrobial activity of chitosan is a hot research topic and there are several articles dealing with it and its derivatives [2, 3, 5–7]. Moreover, chitosan has numerous advantages over other chemical disinfectants since it possesses a stronger antimicrobial activity, a broader range of activity, a higher antibacterial activity even at low concentrations, and a lower toxicity towards mammalian cells [8, 9]. Technological applications of fungal chitosan, as a natural antimicrobial agent, require a new method of detection. he agar difusion method is the most frequently used [10, 11] and has been standardized as an oicial test method for detecting