SYNERGISTIC EFFECT OF Zingiber officinale AND Curcuma longa EXTRACTS

ABSTRACT

Ginger (Zingiber officinale) and Turmeric (Curcuma longa) have been used for over centuries due to its potential antibacterial activity against diversity of microbial pathogens. The aim of this study was to assess the synergistic effects (antibacterial activity) of Zingiber officinale and Curcuma longa extracts on Enterobacteriaceae isolated from fresh vegetables. Fresh vegetables were obtained from an open market in Benin city. The samples were serially diluted and inoculated on MacConkey agar. Enterobacteriaceae isolates were identified through cultural, morphological and biochemical characteristics. Thereafter, ethanolic extracts of Zingiber officinale and Curcuma longa were prepared. The Minimum Inhibitory Concentration (MIC) of the extracts on isolates was determined by the agar well diffusion technique on Mueller-Hinton agar while Minimum Bactericidal Concentration (MBC) was also established. Antibiotic susceptibility test was also carried out on the isolates using the Kirby-Bauer disc diffusion technique. Three isolates were identified. They include Salmonella sp., E. coli and Enterobacter sp. The highest antibacterial zones of inhibition of both extracts against each isolate was recorded at 500 mg/ml concentration. This ranged from 7.00±1.00 mm (Salmonella sp. And Enterobacter sp.) to 8.00±0.00 mm (Escherichia coli). While the MIC of the extracts were 300mg/ml, 350mg/ml, and 500mg/ml for Salmonella sp., Escherichia coli and Enterobacter sp. respectively. Thereafter, an MBC of 500mg/ml was observed for all isolates. Results of the antibiotic susceptibility test showed that Enterobacter sp. recorded the highest resistance index of 5 while Salmonella sp. and Escherichia coli had the lowest antibiotic resistance index of 3. The continued search for antimicrobial agents to combat the issue of multi-drug resistant bacterial species is one of the most important reasons xii for the present study. Therefore, it cannot be overemphasized because a combination of ginger and turmeric extracts shows promise in the use as an antibacterial agent.