Abstract

The Magadi Lake located in the Southern Rift Valley in Kenya is a hypersaline and alkaline lake. The lake’s pH ranges from pH 9 to 11 whereas the salinity can reach saturation during the dry Season. Little studies have previously been done on Lake Magadi as compared to other soda lakes from Kenya. This study concentrated on isolating and characterizing haloalkaliphilic bacteria found in the hot springs of Lake Magadi. Collection of water, wet sediments and microbial mats was carried out from the springs in the main lake at a temperature of 45.1°C and from Little Magadi Nasikie Engida (temperature of 81 and 83.6°C). Seven bacterial isolates were identified using various media prepared with filter-sterilized water from the lake. These isolates were characterized and analyzed for production of extracellular enzymes and antimicrobial compounds. Bacteria recovered, thrived at pH ranging from 6 to 14, a temperature range of 30 to 60°C and sodium chloride range of 0 to 17.5%. The isolates produced amylases, lipases, proteases, cellulases, xylanases, esterases and also exhibited a range of inhibitory effects on various test organisms. Sequencing of the 16S rDNA of the isolates was done and sequences for 7 isolates were without ambiguities. BLAST results revealed that 90% of isolated microbes had an affiliation to the genus Bacillus while 10% was affiliated to genus Gammaproteobacteria. Strains from Bacillus family included; Bacillus siamensis, Bacillus licheniformis, Bacillus methylotrophicus, Bacillus amyloliquefaciens, Bacillus pumilus, and Bacillus sonorensis while one strain that belonged to Alcaligenes family was Alcaligenes feacalis.

Key words: Hypersaline, Little Magadi, alkaliphilic, hot springs, filter-sterilized.