ANTIBACTERIAL EFFECT OF LEAF EXTRACTS OF OCIMUM GRATISSIMUM ON FAECAL INDICATORS AND PATHOGENS ISOLATED FROM AN EARTHEN POND

Abstract

Ocimum gratissimum has been demonstrated to be a plant of medicinal importance. This study was aimed at determining the antibacterial activities of Ocimum gratissimum on enteric bacteria isolated from water samples from an earthen pond. Sixteen water samples were collected from an earthen pond behind Great Hall Obakekere Federal University of Technology, Akure from April to July, 2019. The load of enteric bacteria in the water samples was determined using membrane filtration method. The physicochemical characteristics of the water samples were determined using standard method. The phytochemical constituents of the leaf extracts of O. gratissimum was determined quantitatively and qualitatively using standard methods. Agar well diffusion and disk diffusion methods were used to determine the antibacterial effect of leaf extracts of Ocimum gratissimum and commercial antibiotics on the isolates respectively. Results showed that the concentration of E . coli ranged from 4.4 × 101 CFU/100 ml to 6.8 × 101 CFU/100 ml, Salmonella ranged from 4.8 × 102 CFU/100 ml to 4.48× 103 CFU/100 ml, Shigella ranged from 3.48× 103 CFU/100 ml to 29.28× 103 CFU/100 ml and faecal coliforms ranged from 6.18×103 CFU/100 ml to 1.968×104 CFU/100 ml. The pH of the water ranged from 6.78 to 7.87, whereas the turbidity ranged from 26 to 47.5 NTU. Saponin, tannin, flavonoid, steroids, terpenoids, cardiac glycosides were present in ethanol extract of O.gratissimum,but lacked alkaloids, phlobatannin and steroids. Aqueous extract of O. gratissimum was positive for saponin, tannin, flavonoid, terpenoid, cardiac glycosides but lacked alkaloids, phlobatannin and steroids. The leaf extracts of O. gratissimum contained saponin (15.6363, 33.6363), tannin (18.102, 31.164), flavonoid (8.586957, 13.61801), steroid (5.2918, 0.0), terpenoid (22.8457, 9.4415), alkaloid (0.0, 0.0), glycosides (14.5008, 23.2217) and phlobatannin (0.0, 0.0). The leaf extracts of O. gratissimum exhibited no significant zone of inhibition on the isolates. The findings from this study suggested that the leaf extracts of O .gratissimum do not have antibacterial effect on E . coli, Salmonella and Shigella isolated from water samples from the earthen pond behind Great Hall, Obakekere FUTA.