Abstract

Hot springs are aquatic environments with high temperatures. They harbor diverse groups of micro-organisms like fungi that have developed mechanisms to thrive at wide temperature ranges, according to their optimal growth requirements. Fungi are a large group of eukaryotic organisms with worldwide distribution, inhabiting a diverse range of extreme habitats from deserts to hyper saline environments. The fungal diversity of the hot spring along the shores of Lake Bogoria was investigated using a culture-dependent approach. Microbial mats and wet sediments were collected from three sampling points along the hot spring while water samples were gotten from the mouth of the hot spring on the shores of the lake. Physicochemical characteristics were recorded at the study sites. Samples from the hot spring were isolated on four different media at pH 10 and at a temperature of 30°C. A total of seventeen fungal isolates were identified using morphological, physiological and molecular characters. Furthermore, the isolates were screened for production of extracellular enzymes. All the fungal isolates variedly grew at pH ranging from 5 to 10, temperature range of 25 to 35°C and sodium chloride range of 5 to 30%. Based on experimental analysis, isolate B61 exhibited significant growth in the four parameters tested. Also all the seventeen isolates produced different extracellular enzymes such as amylases, lipases, proteases and esterases. Analysis of partial sequences using Blastn showed that about 11.7 and 29.1% of the isolates were affiliated with members belonging to the genera Penicillium and Aspergillus, respectively. A total of 12% of the isolates belonged to the genera Alternaria and Fusarium while another 41% of the isolates clustered closely with uncultured fungus. Fungal endophyte comprised 6%. Although the culture dependent method did not reveal the true diversity of the fungal community, the isolates recovered were a representation of thermotolerant, alkalitolerant and halotolerant microorganisms found in soda lake environments. The isolates have the potential to produce useful enzymes for biotechnological applications.

Key words: Hot springs, tropical mycology, diversity, extremophiles.