An Evaluation of Antimicrobial Activity of Common Zingiber officinale Cultivars Grown in Sri Lanka

Ginger (Zingiber officinale) has long been a therapeutic agent in traditional medicine systems worldwide and is a leading drug candidate in the pharmaceutical industry. In Sri Lanka, many forms of ginger are often used in the food industry, mainly as a spice; it also plays a vital role in the Ayurvedic medicine system. This study evaluated the antimicrobial activity of the two most cultivated cultivars of Zingiber officinale in Sri Lanka, the Sri Lankan (TG) and Chinese (CG) cultivars. Two types of extracts (ethanol and aqueous) were obtained from the rhizomes of each cultivar. The potential antimicrobial activity of the extracts was tested against three types of pathogenic test organisms, Staphylococcus aureus ATCC 25923, Salmonella typhi DSM 17058, and Escherichia coli ATCC 25922, using the agar well diffusion method along with positive control, chloramphenicol, and negative controls, 95% ethanol or distilled water. In conclusion, both Zingiber officinale cultivars exhibit varying antimicrobial potential, with ethanol extracts showing stronger activity than aqueous ones. None of the extracts was effective against Escherichia coli. The agar dilution method determined the minimum inhibitory concentration (MIC) of each ginger extract. Among the extracts, ethanol extracts showed higher effectivity than aqueous extracts, where all test organisms showed inhibition at a concentration of 20 mg/mL. The antimicrobial activity of the Chinese cultivar outperforms the Sri Lankan cultivar against target organisms, Salmonella typhi, and Staphylococcus aureus.