Metagenomic analysis of bacterial diversity of Siloam hot water spring, Limpopo, South Africa

The bacterial diversity of Siloam hot water spring was determined using 454 pyrosequencing of two 16S rRNA variable regions V1-3 and V4-7. Analysis of the community DNA revealed that the phyla Proteobacteria, Cyanobacteria, Bacteriodetes, Planctomycetes, Firmicutes, Chloroflexi and Verrucomicrobia were the most abundant. The bacterial diversity detectable and classifiable was greater when the V4-7 variable region was used compared to the V1-3 region. The most abundant bacteria genera detected with region V1-3 were; Stenotrophomonas (23.3%), Aquaspirillum (5.11%), Zavarzinella (2.73%), Haliscomenobacteria (1.25%), Rheinheimera (1.14%) and Tepidomonas (1.14%). All the other detectable genera were below 0.6%. Genera detected with region V4-7 from most abundant were; Stenotrophomonas (17.96%), Zavarzinella (5.81%), Aquaspirillum (4.75%), Rheinheimera (3.52%), GPI (1.41%), Gemmata (1.41%) and Syntrophobacter (1.06%). All the other genera detected were below 0.7%. Siloam is one of the hottest thermal springs in South Africa (63 degrees C), the water has a pH of 9.5 and is relatively high in fluoride and bromide; it is possible that the physicochemical properties could have some influence on the diversity of bacteria. This article reports on the first phylogenetic analysis of a South African thermal spring bacterial community.