Antimicrobial activities of <i>Zingiber officinale</i> (ginger) and <i>Curcuma longa</i> (turmeric) on some reference bacterial strains

Abstract

The antimicrobial activities of Zingiber officinale (Ginger) and Curcuma longa (turmeric) were studied on selected pathogens using standard microbiological techniques. Reference strains: Enterococcus durans ATCC 11576, Enterococcus faecalis ATCC 19433, Enterococcus faecium ATCC 35667, Enterococcus gallinarium ATCC 49573, Enterococcus hirae ATCC 49135, Pseudomonas aeruginosa ATCC 27853, Aeromonas hydrophila ATCC 7966, Acinetobacter baumanni ATCC 19606, Stenotrophomonas maltophilia ATCC 13637 and Escherichia coli WG5 were obtained from GI-Microbiology/Biotechnology Agriculture Research Council, Irene and Durban University of Technology, South Africa. Crude ethanolic extracts and partitioned fractions; dichloromethane, ethyl acetate, n-hexane and 1-butanol were also investigated. Antimicrobial activities of the ethanolic extracts of Z. officinale and C. longa showed zones of inhibition that ranged from 9 mm to 13 mm and 10 mm to 18 mm respectively against the test isolates. Z. officinale ethanolic extract showed no activities against Enterococcus gallinarium ATCC 49573 and Enterococcus hirae ATCC 49135 while C. longa ethanolic extract showed activities against all the test isolates. Various fractions showed inconsistent antimicrobial activities. The largest zone of inhibition was obtained from n-hexane (ZI= 22 mm) fraction of C. longa while Z. officinale crude extract showed zone of inhibition (ZI= 13) against all the tested isolates. Partitioned extracts showed 8-22 mm zone of inhibition with turmeric having the largest zone of inhibition. Activities in these extracts can be attributed to repertoire of phytochemical constituents, especially the Alkaloids and Flavonoids detected in them. These activities can be utilized for preservation purposes of food since both turmeric and ginger are edible natural spices.