Comparative Study of Ocimum gratissimum Mediated Nanoparticles and Conventional Antibiotics against Endophytic Leguminous Bacteria and Selected Clinical Isolates

Abstract

The purpose of this research work is to compare the antimicrobial activities of conventional antibiotics and Ocimum gratissimum mediated nanoparticle against microorganisms isolated from endosphere of leguminous plants and selected clinical organisms. The microorganisms are becoming a resistant reservoir to conventional antibiotics, there is a great need, to research into plant mediated nanoparticles, to combat this great menace of resistant organisms, this therefore was the basic hypothesis of this research work. The Endophytic Leguminous plants used for this research work were Mucuna pruriens, Calopogonium mucunoides and Vigna unguiculata. The plants were randomly collected from Federal College of Agriculture, Akure (7.2704° N, 5.2241° E).Endophytic bacteria were isolated, identified and characterized from the endospheres of the leguminous plants using biochemical test, sugar fermentation and Bergey’s manual. The antimicrobial susceptibility test for endophytic isolates and clinical isolates were performed using Kirby-Bauer disc diffusion technique.The same procedure was repeated for the two sulfur nanoparticles The sulfur nanoparticles were synthesized using Sodium thiosulfate pentahydrate, citric acid (C_6 H_8 O_7,AR) with leaf extract of Ocimum gratissimum, SNP1 and SNP2 (Solid reflectance spectrum); SNP1/SNP2 was synthesized in the presence/absence of O. gratissimum and characterized on shimadzu UV-VIS-NIR spectrophotometer UV-3100 with a MPCF-3100 sample compartment. The probable number of organisms isolates from the leguminous plants ranges between 109-1022 cfu and all the endophytic isolates were found to be Gram positive rods. The probable organisms isolated from the leguminoius plants were Microbacterium lacticum, Cellulomonas flavigena and Bacillus spp including;B. pumilus, B. subtilis and B. amylolyticus. Bacillus subtilis. All endophytic bacteria were resistant to antimicrobial susceptibility test using Cephalosporins (oxoid) and multiple susceptibility disc with a diameter between 11mm and 20mm. Endophytic bacteria were susceptible to the SNP1 sulfur nano particles with a diameter between 9mm and 14mm diameter zones of inhibition. The clinical isolates were susceptible to multiple susceptibility disc with of diameter of 11mm and 20mm. Antimicrobial susceptible to SNP1 ranges between  18-20mm zones of inhibition  to SNP2.This study discovered that nanoparticles has better antimicrobial efficacy against both endophytic isolated bacteria and clinical isolates. The present of Ocimum gratissimum drastically increases the efficacy of sulpur mediated nanoparticles. it can be deduced that the Ocimum gratissimum mediated nanoparticle as a potential alternative to antibiotics in this widespread antibiotics resistance era.