Isolation and characterization of antibiotic producing thermophilic bacillus in selected hot-springs along lake Bogoria, Kenya
Torome, Tom Kintet
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Extreme habitats are increasingly being recognized as sources of secondary metabolites which provide an encouraging source for development of novel natural pharmaceuticals. Saline and hot water lakes are now becoming appreciated as rich and untapped reservoirs of extremophilic microorganisms with previously uncharacterized functions. Bacilli, a large homogeneous group of bacteria that survive in a wide range of environmental conditions, is one such microorganism. Formation of resistant spores allows it to survive in high temperatures zones where other organisms cannot. The objective of this study was to isolate, identify, and characterize Bacillus organisms with the potential to produce secondary metabolites with antibacterial properties from the hot springs of Lake Bogoria. Eighty samples were collected from surface and sediment waters of selected hot springs and inoculated directly into nutrient broth in universal bottles. Samples were initially incubated at 45oC for 48 hours and growth was examined by checking for turbidity. Out of the 80 bottles inoculated with sample, thirty three exhibited growth. Subsequent streaking on nutrient agar and Gram staining showed that nine of the isolated organisms were Gram-positive rods, twenty were Gram-negative rods, and four were Gram-positive cocci. Only Gram-positive rods were processed further. Biochemical characterization revealed that all nine processed isolates were catalase-positive and non produced gas upon sugar fermentation. They however had varying results for indole, motility, lactose fermentation, glucose fermentation and H2S production. Antibacterial profiling was performed using ATCC organisms: Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922, Escherichia coli 35218, and Pseudomonas aeruginosa ATCC 27853. Isolates D1, D5, D8, D22 and S15 inhibited growth of Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 which was shown by clear zones of inhibition around the discs. No inhibition was noted against S. aureus ATCC 29213 and E. coli 35218. Phylogenetic analysis of amplified 16S rDNA gene showed that D1, D5, D8, D22 and S15 formed close phylogenetic clusters with known members of Bacillus organisms with a (88-99%) sequence identity. The current study shows the presence of thermophilic Bacillus species, which are producers of biomolecules with antibacterial properties within the hot springs of Lake Bogoria. Characterization of the antibacterial compounds produced will be useful for the discovery of novel antimicrobial substances that are effective against wide range of pathogens.