Mangrove ecosystems provide a unique ecological niche for diverse microbial communities. This study aimed to identify bacterial isolates from the rhizospheres of four mangrove species (Sonneratia alba, Rhizophora mucronata, Ceriops tagal and Avicennia marina) using the 16S rRNA gene analysis approach. Rhizospheric sediment samples of the mangroves were collected from Mida creek and Gazi bay, Kenya, using standard protocols. A total of 36 representative bacterial isolates were analyzed. The isolates were characterized using morphological and molecular characters. Pure gDNA was extracted from the isolates, polymerase chain reaction amplified and sequenced. The 16S rRNA gene sequences were BLASTN analyzed against the Genbank database; the closest taxonomically related bacterial sequences were retrieved and used for phylogenetic analysis using MEGA X software. Morphologically, the isolates differed in their cultural characteristic in color, shape, margin, elevation and gram reaction. Phylogenetic analysis classified the isolates into five genera, namely Bacillus, Pseudomonas, Micrococcus, Microbacterium and Streptomyces that belong to three different phyla (Firmicutes, Proteobacteria and Actinobacteria). The findings show that the underexplored tropical mangrove rhizospheres harbor useful diverse bacteria. Further analysis of the bioactive production potential of the isolates will give more insights into the types of bioactive compounds produced and their biotechnological potential.
Key words: 16S rRNA gene sequence, rhizosphere, mangrove sediments, marine bacteria, biotechnology.
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