Effect of Water Stress (Drought) on the Antimicrobial Activity of the Leaves of Ocimum gratissimum L.and Gongronema latifolium Benth.

摘要

The effect of water stress (drought) on the antimicrobial activity of the leaves of Ocimum gratissimum L. and Gongronema latifolium Benth. was investigated. Cultivated O. gratissimum and G. latifolium, planted in buckets, were subjected to mild stressby supplying each bucket with 500 ml of water once a week, while the control treatment was supplied with 750 ml of water three times a week. The treatment commenced 2 months after seedling emergence. Leaves were harvested for the sensitivity test one month from the date of commencement of treatment. The sensitivity test of the ethanolic extracts of the harvested leaves was applied to Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Streptococcusfaecalis, Candida albicans and Aspergillus niger. Water stress (drought) significantly (P < 0.05) reduced the antimicrobial activity of O. gratissimum and G. latifolium leaves except for Candida albicans, whose growth reduction was not significant. Therewas a decrease in the inhibition zone due to water stress treatment. The ethanolic extracts of the leaves of both plants had no antimicrobial effect on A. niger. Water stress (drought) reduced the bioactive substances in the leaves which in turn affected the ability of the extracts to inhibit pathogenic activity, thus affecting the efficacy of the plants as medicinal plants.