9 Saifur et al. Int. J. Biosci. 2014 RESEARCH PAPER OPEN ACCESS Ethanol extract of Curcuma longa leaf, a potential drug candidate against Bacillus species mediated infections Rahman Md Saifur 1 , Hasan K.D.B 1 , Muslima Jahan 1 ,Sudhangshu Kumar Biswas 1 , M.A. Haque 1 , M.R. Islam 1 , Md Enamul Haque 2 , Tama Sarkar 3 ,Nirupam Biswas 1,4* 1 Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia 7003, Bangladesh 2 Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka-1000, Bangladesh 3 Department of Applied Nutrition and Food Technology, Islamic University, Kushtia 7003, Bangladesh 4 Department of Nutrition and Food Sciences, School of Applied Sciences, University of Huddersfield, Huddersfield, United Kingdom Key words: Curcuma longa, Bacillus species, MIC, Disk diffusion method. http://dx.doi.org/10.12692/ijb/4.7.9-14 Article published on April 01, 2014 Abstract Several studies have exposed the antimicrobial and antioxidant activities of Curcuma longa, widely used in food industry as a colorant, among other functions. This study was implemented to examine the antimicrobial activity of Curcuma longa leaves against six Bacillus species. Antimicrobial activities of three different extracts of Curcuma longa leaves on Bacillus species were tested on the basis of disk diffusion method and the zone of inhibition was measured. The ethanol extract of the plant leaf produced maximum zone of inhibition against Bacillus cereus Xb21 (12.50mm) followed by Paenibacillus sp. BF38 (11.10mm), Bacillus simplex Xb17 (10.40mm), Bacillus megaterium Hb42 (9.15mm), Paenibacillus sp. L32 (8.00mm) with the exception of Terribacillus sp. 3LF showed resistance, whereas the ethyl acetate and hexane extracts did not exhibit against all the tested bacteria. The chloroform extract of Curcuma longa leaves exhibited against only Bacillus simplex Xb17 (14.45mm) and Paenibacillus sp. BF38 (12.25mm).The MIC (minimum inhibitory concentration) values of ethanol extract against tested bacteria were almost 15.625 μg/10µl.The results suggest that the ethanol extract of Curcuma longa leaves could be considered as potentially effective antimicrobial agents against tested Bacillus species. * Corresponding Author: Nirupam Biswas  nirupamgene@gmail.com International Journal of Biosciences | IJB | ISSN: 2220-6655 (Print) 2222-5234 (Online) http://www.innspub.net Vol. 4, No. 7, p. 9-14, 2014