*1,[1]Kiboi, N., 3Abonyo, C., 4Mwiti, B., 5Marera, D., 4Ngugi, M. P., and 6Were, T
1Department of Medical Laboratory Sciences, South Eastern Kenya University, Kitui, Kenya
2Department of Medical Laboratory Sciences, Masinde Muliro University of Science and Technology, Kakamega, Kenya
3Department of Medical Laboratory Sciences, Alupe University, Busia, Kenya
4Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya
5Department of Human Anatomy, Maseno University, Maseno, Kenya
6Department of Pathology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
*Correspondence to: nathankiboi@gmail.com; +254 718-145-100; ORCiD: https://orcid.org/0000–0002–2417–6399
Abstract:
Background: The extensive saline-alkaline ecosystem is increasingly gaining recognition as a rich source of haloalkaliphilic fungal biota whose ecological roles remain less explored. Equally, hot water and saline releasing lakes are being appreciated as untapped natural sources of fungal extrolites bearing unique chemical bioactivities. Existing literature reveals scanty evidence on fungal biodiversity in East African Rift-valley soda lakes. This study sought to bio-prospect Lake Magadi in Kenya as a source of extremophilic fungal microbial diversity.
Methodology: A laboratory-based experimental study was conducted using simple random sampling to select 9 mark-points in the lake for establishment of fungal morphological and molecular characterization. Wet sediments, surface water and soil samples were collected from each sampling site in triplicate and cultured on Sabouraud’s Dextrose Agar (SDA), Potato Dextrose Agar (PDA) and Malt Extract Agar (MEA) plates at 250C and 410C for 1-3 weeks, to isolate and identify fungi by conventional macro and microscopic morphology. The ITS-1 and ITS-4 universal fungal primer pairs were used to amplify extracted fungal DNA from isolates, followed by Sanger sequencing. The NCBI BLASTn was used for molecular identification and evolutionary relationships were inferred using neighbor-joining method with 1000 bootstrap support. The salinity, pH, electrical conductivity (EC) and total dissolved solids (TDS) of the samples were measured onsite using portable pH meter and double interface electrical-chemical analyzer.
Results: A total of 30 fungal isolates were recovered from the samples using culture based and molecular techniques. Fungal sporulation was observed at pH 8–9 and salinity of 9.6–10.8 ppm. Growth was more evident at 250C (n=25) compared to 410C (n=5), and further supported on SDA (n=16) relative to MEA (n=10) and PDA (n=4). Wet sediments accrued highest diversity of fungal biota (n=15). Phylogenetically, isolates were affiliated to 9 genera with Cladosporium (n=8), Aspergillus (n=5) and Penicillium (n=4) displaying dominance. The genera Aspergillus and Penicillium alongside Fusarium and Sarocladium exhibited close evolutionary affiliation as sister groups with overlapping clades.
Conclusion: The findings of this study validate existence of diverse fungal community species discerned through observed distinct phenotypic features vis-a-vis molecular identities. Diversity and taxonomic richness are significantly influenced by pH, salinity, temperature and variable cultivation media types. Metagenomic tools including DNA pyrosequencing and whole genome sequencing can enhance heightened detection of diverse microbial biota across East African saline-alkaline ecosystems.
Keywords: Haloalkaliphilic, Characterization, Saline-alkaline, Extremophiles, Hot-spring, Kenya
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