Abstract

There is still unexplored reservoir of microorganisms from sediments and water within Lakes Olbolosat and Oloiden using culture dependent technique. The current study compares bacterial diversity within Lake Olbolosat a freshwater lake and Lake Oloiden a saline alkaline lake. Out of 60 isolates obtained from sediments and water samples, 35 were from Lake Olbolosat and 25 from Lake Oloiden. Microbial count ranged between 0-1.75× 10⁵ cfu/ml from both lakes. There was a significant difference between bacterial density and sampling points (p<0.001, F=6.667), 58 were Gram-positive and 2 Gram-negative. Fifty-five isolates that were rod-shaped, 3 were cocci and 2 filamentous. There was excellent growth of isolates at an optimum growth pH range of 6-10, a temperature range of 25-30°C and a salinity range of 0-5%. There was significant difference at p<0.001 for bacterial growth within physiological parameters. The isolates utilized skimmed milk, starch, olive oil, cellulose powder and xylan, hence the production of extracellular enzymes. There was antimicrobial activity against Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Candida albicans by bacterial isolates. BLAST analysis of partial sequences showed there were 4 different phyla.  Firmicutes scored 77% closely affiliated with 20 strains, Actinobacteria scored 15% closely affiliated with 4 strains, Proteobacteria and Bacteroidetes scored 4% affiliated with 1 strain each. Novel bacteria from this study could provide insights into their diversity and biotechnological applications.

Keywords: Lakes, bacteria, sediment, water, culture-dependent.