Plant 2017; 5(5-1): 13-18 http://www.sciencepublishinggroup.com/j/plant doi: 10.11648/j.plant.s.2017050501.12 ISSN: 2331-0669 (Print); ISSN: 2331-0677 (Online) Research Article Study on Antibacterial Activity of Cajanus cajan L. Against Coliforms Isolated from Industrial Waste Water in Bangladesh Md. Motiar Rahman 1 , Md. Sahab Uddin 2 , Md. Rashed Nejum 1 , S. M. S. Al Din 1 , G. M. Sala Uddin 1, 2, * 1 Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia, Bangladesh 2 Department of Pharmacy, Southeast University, Dhaka, Bangladesh Email address: salauddiniu04@gmail.com (G. M. S. Uddin) * Corresponding author To cite this article: Md. Motiar Rahman, Md. Sahab Uddin, Md. Rashed Nejum, S M S Al Din, G. M. Sala Uddin. Study on Antibacterial Activity of Cajanus cajan L. Against Coliforms Isolated from Industrial Waste Water in Bangladesh. Plant. Special Issue: Phytotherapy. Vol. 5, No. 5-1, 2017, pp. 13-18. doi: 10.11648/j.plant.s.2017050501.12 Received: July 7, 2016; Accepted: October 9, 2016; Published: October 18, 2016 Abstract: Infectious diseases are one of the foremost causes of mortality and morbidity. In addition, day by day infection causing microbes are becoming resistant and modifying themselves into multi-drug resistant strains. So there is a crucial need to introduce new antibiotics to fight against these pathogens. The synthetic antibiotics are effective, but unsafe as well as are not consistent to use owing to the resistance building capacity of the microbes. Consequently, there is greater need for alternative treatments. Medicinal plants are store house of various types of phytochemicals and considered as a potential therapeutic remedy for numerous ailment. Therefore the aim of the present study was to evaluate the antibacterial activity of the leaves extract of Cajanus cajan (C. cajan) L. against coliform bacteria collected from tannery, tobacco and sugar mill waste water. In this study fresh leaves of C. cajan was extracted by using ethyl acetate, chloroform and n-Hexane. The antibacterial activity of these plant extracts was determined by measuring zone of inhibition (ZI) using the Agar disk diffusion method and minimum inhibitory concentration (MIC) was determined by using the microbroth dilution method. Among three extracts highest (25±0.18 mm, ZI) antibacterial activity was reported by ethyl acetate extract of C. cajan leaves against coliform bacteria isolated from sugar mill waste water at the highest concentration with respect to chloroform and n-Hexane extracts. In addition, antibacterial activity was also higher for ethyl acetate extract against coliform bacteria isolated from tannery and tobacco waste water compared to remaining extracts. The MIC of the ethyl acetate extract ranged 550 to 570 µg/ml. Therefore ethyl acetate extract of C. cajan leaves could be used as antibacterial agents against diseases caused by coliforms. Keywords: Antibacterial Activity, Cajanus cajan, Coliforms, Multi-drug Resistant, Waste Water 1. Introduction In the history of human ancestry plants have been used for human being owing to various medicinal properties even in modern time have formed many pharmaceuticals on the basis of plant and plant materials [1, 2, 3]. It produces a vast amount of secondary metabolites as defense against environmental stress and other factors like pest control, wound and injuries [4, 5, 6]. In case of human being pathogenic bacteria have always been suggested as one of the major cause of various diseases [7]. Worldwide drug resistance is now a matter of great concern, although pharmaceutical company has continuously generated in various types of antibacterial agents [8]. Search of new drugs is an increasing incidence in many researches due to the adverse side effect associated with conventional drugs, resistant to antibiotics and to combat the multi-resistant microorganism [9-12]. Coliform bacteria are Gram-negative, rod-shaped, spore forming and motile or non-motile bacteria [13]. These bacteria that are present in the digestive tracts of warm-blooded animals,