Browsing by Author "Muigai, A.W."

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    Bacterial Diversity in the Haloalkaline Lake Elmenteita
    (Springer-Verlag, 2010-06) Mwirichia, Romano K.; Cousin, S.; Muigai, A.W.; Boga, Hamadi I.; Stackebrandt, Erko
    Lake Elmenteita is one of the alkaline saline lakes within the Kenyan Rift valley. The lake is situated on the floor of the Kenyan Rift Valley at 1,776 m above sea level and has no direct outlet. The microbial diversity of the lake was investigated using a culture-independent approach. Five different sampling points were selected randomly within the lake. Wet sediments and water samples were collected from each sampling point. In addition, dry mud cake was collected from three points where the lake had dried. DNA was extracted from the samples and the 16S rRNA genes amplified using universal primers for Bacteria. Thirteen clone libraries were constructed using the PCR amplified 16S rRNA genes. A total of 1,663 clones were picked. Representative clones were selected using ARDRA technique for sequencing. 655 partial and non-chimeric clone sequences indicated the presence of 37 orders in the Domain Bacteria. Cyanobacteria were the most abundant clones in terms of numbers whereas members of the phylum Firmicutes group were the second in terms of numbers but the most diverse in terms of genera represented. All clones affiliated to the class Betaproteobacteria originated from DNA obtained from the water samples. Analysis using BLAST showed that 93.1% of the sequenced clones had similarity values below 98% to both cultured and as yet uncultured bacteria, resulting in 596 phylotypes. Therefore, it can be concluded that Lake Elmenteita harbours phylogenetically diverse groups of bacteria involved in complex metabolic interactions within the Lake’s ecosystem.
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    Isolation and characterisation of bacteria from the haloalkaline Lake Elmenteita, Kenya
    (Springer, 2010-04) Mwirichia, Romano K.; Muigai, A.W.; Tindall, B.; Boga, Hamadi I.; Stackebrandt, E.
    Culture-independent studies show that soda lake environments harbour diverse groups of bacteria and archaea. In this study different enrichment and isolation media were used in an attempt to isolate novel groups of bacteria from Lake Elmenteita. Different media were prepared using filter-sterilised water from the lake. The isolates recovered were purified on tryptic soy agar supplemented with 1% sodium carbonate and 4% sodium chloride. Phylogenetic analysis of 181 partial 16S rRNA gene sequences with excellent quality showed that the majority of the isolates were affiliated to the class Gammaproteobacteria and to the genus Bacillus. Isolates from the genus Halomonas and Bacillus constituted 37 and 31% of the total sequenced isolates, respectively. Other groups recovered were related to Marinospirillum, Idiomarina, Vibrio, Enterococcus, Alkalimonas, Alkalibacterium, Amphibacillus, Marinilactibacillus and the actinobacteria Nocardiopsis and Streptomyces. Fifty-one different genera were represented with 31 and 15 cultures scoring with their nearest neighbour similarities below 98 and 97%, respectively. Some novel taxa were identified which had not been isolated previously from the soda environment. The results show that the use of different media with varying compositions can help retrieve novel bacterial diversity from the soda lake environment.