Bioefficacy of Turmeric Rhizome Extracts with Alum on Microbes: An in Vitro Approach

Abstract

Bioefficacy of crude Turmeric rhizome extracts and in combination with alum against four (4) bacterial and five (5) fungal species were determined using disc diffusion (DD) and agar well diffusion (AWD) methods respectively. The extracts with or without Alum were active against all the test microbes in dose-dependent manner by inhibiting their growth. The highest diameter of inhibition zone (DIZ) was observed with ethanolic turmeric extract (ETE) and alum (ETE+Alum) at 0.3g concentration on Gram negative bacteria; Escherichia coli (16.6±0.8mm) and Pseudomonas fluorescens (15.3±1.1mm) and Gram positive bacterium; Staphylococcus aureus (15.0±0.0mm) whereas strong antimycotic activity occurred with Alum in the order Aspergillus terreus (17.5±1.0mm) > A. flavus (17±1.0mm) > S. cerevisiae (14mm) > C. albicans (12±1.0mm) by DD respectively. Using AWD bioassay, alum exhibited the best activity against Bacillus cereus (17.8±1.0mm), S. aureus (16.0 ± 0.7mm) and 14.0mm on P. fluorescens and E. coli whereas ETE+Alum demonstrated highest antimycotic activity on A. terreus (35±1.0mm) > Penicillium crystallium and A. flavus (33.0mm) > S. cerevisiae (24.0mm). Furthermore, the demonstration of apparent antimicrobial activity on both Gram positive and Gram negative bacteria as well as against moulds and yeasts by extracts of Turmeric rhizome` and Alum is suggestive of broad spectrum activity. In contrast, however, the high activity of Ofloxacin (OFL) and Ketoconazole (KTA) against test microbes highlights their superiority to the extracts with or without alum. However, enhancement of bioefficacy of Turmeric rhizome extracts was achieved by incorporation of Alum and such novel approaches to research with safe, natural products would provide an alternative to antibiotic and antifungal treatment of diseases of plants, animals and humans in future.