Activity of endophytic extract from Zingiber officinale rhizomes against antibiotic-resistant bacteria
Abstract
Endophytic secondary crude metabolite obtained from Zingiber officinale rhizomes were subjected to phytochemical screening, antibacterial property and Minimum Inhibitory Concentration (MIC) determination. Identification through DNA analysis was also done on four endophytes that produced crude extracts with antibacterial activity. Multidrug-resistant Mycobacterium tuberculosis, Methicilin-Resistant Staphylococcus aureus (MRSA), extended-spectrum β-lactamase Escherichia coli (ESBL E.coli) and Multi-drug resistant Acinebacter spp. (MDR-A) were used to test antibacterial activity. Antibacterial activity for test microorganisms yielded 10.5mm, 2mm and 3mm zones of inhibition for MRSA, ESBL E. coli and MDR-A respectively. Both antibacteriala ctivities of 100 µg crude extracts against MRSA and MDR-A were similar to the standards used: 10 µg Vancomycin (11mm) for MRSA and 10 µg Chloramphenicaol (3mm) for MDR-A. Only one crude extracts was able to inhibit the growth of ESBL E. coli at 15% inhibition compared to the standard, Meropenem. All crude extracts showed inhibition against Mycobacterium tuberculosis with the highest being 68% in comparison with the standard, Isoniazid. MIC values for ESBL E. coli and MDR-A were 100 µg and 50 µg for MRSA. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, terpenoids, saponins and coumarins. Chryseoibacterium indologenes, Pseudomonas nitroreducens, SPhingobacterium sp. B29 and Bacillus amyloliquifaciens were successfully isolated from Zingiber officinale rhizomes that produced antibacterial crude metabolites. Two solvent systems (DCM: Hexane:Ethyl acetate and Ethyl Acetate:Hexane) through Thin Layer Chromatography (TLC) were used to separate three to four compounds present from the endophytic extract able to inhibit Mycobacterium tuberculosis and can be considered for used as template for subsequent future expansion of the study.