Anti-bacterial Effect of Aqueous and Ethanolic Extracts of Onion, Garlic and Cinnamon on Xanthomonas Species

Abstract

Onion (Allium cepa), garlic (Allium sativum) and cinnamon (Cinnamomum zeylanicum) are edible herbs but they contain many chemicals which can be used as medicine. These herbs also contain many antibiotic molecules that are capable to inhibit or reduce growth of many types of microbes including bacteria. Due to the development of resistance of bacteria against synthetic antibiotic now there is a need to have natural antibiotic which must be harmless, cheap and easily available. To know the effectiveness of garlic, onion, and cinnamon on disease causing bacteria such as Xanthomonas campestris pv. malvacearum, Xanthomonas axonopodis pv. citri, Xanthomonas oryzae pv. oryzae, extracts of each sample was made in water and ethanol. Antibacterial potential of plant extracts was observed at two different stages: at the time of inoculation and after growth of pathogen on media. Results showed extracts applied on all the bacteria before growth inhibited maximum bacterial growth as compared to applied after growth. Moreover, cinnamon extract in ethanol effectively control bacterial growth than onion and garlic extracts. Maximum inhibition zone was shown by ethanolic extract of cinnamon before growth of Xanthomonas oryzae pv. oryzae (7.333 mm), Xanthomonas campestris pv. malvacearum (7.83 mm) and Xanthomonas axonopodis pv. citri (5.1 mm). After 24 hours, maximum growth of Xanthomonas oryzae and Xanthomonas axonopodis was inhibited by ethanolic extracts of cinnamon (2.82 and 3.35 mm, respectively) while Xanthomonas campestris was inhibited by ethanolic extract of onion (6.55 mm). Extract diluted from 66mg/ml to 0.01mg/ml showed different minimum inhibitory concentration against pathogens. As concentration decreases inhibition of bacteria also decreases. Ethanolic extracts of cinnamon showed maximum MIC against Xanthomonas campestris pv. malvacearum (3.5 mm to 1.5 mm) and Xanthomonas oryzae pv. oryzae (5 mm to 2 mm) while for Xanthomonas axonopodis pv. citri ethanolic extract of garlic (3 mm to 1 mm) was effective ranging between 66mg/ml to 33 mg/ml. This study highlighted that natural products possess ability to inhibit pathogenic bacterial growth and would also be helpful in medicinal field for further study.