Abstract

High global prevalence of multidrug-resistant bacteria due to antibiotics misuse has prompted the need for novel antibacterial compounds to replace the failing antibiotics. This study investigated some natural habitats in Abuja, Nigeria, for antibiotics-producing bacteria. Thirty-six soil samples from termite mounds, river banks and rhizospheres of Anacardium occidentale L. (cashew tree), Gmelina arborea Roxb. ex Sm. (beechwood), Ageratum conyzoides L. (goat weed) including Cymbopogon citratus (DC) Stapf. (lemon grass) were cultured on nutrient media. Twelve potential antibiotic-producing isolates were identified by crowded plates method and characterized using Bergey’s manual. The antimicrobial activities of the filtrates from the isolates against some pathogenic strains namely Streptococcus pneumonia, Salmonella typhi, Escherichia coli (ATCC 25922), Proteus mirabilis, Staphylococcus aureus (ATCC 25923), Candida albicans, Bacillus subtilis and Pseudomonas aeruginosa (ATCC 27853) were determined by agar-well diffusion method. Only 5 eventually inhibited at least 1 test microorganism; 4 showed activities against both Gram-positive and Gram-negative bacteria (broad spectrum) and 2 among the 4 also inhibited Candida albicans, while the remaining 1 inhibited only 1 Gram-positive bacterium (narrow spectrum). The 5 potent antibiotics-producers were Bacillus spp.  In conclusion, some natural habitats in the FCT are important sources of antibiotic-producing bacteria.  Their antimicrobial lead compounds could be extracted and developed locally for pharmaceutical applications.  

Key words:  Antibiotics-producing bacteria, Bacillus species, natural habitats.