Isolation of obligately alkaliphilic magnetotactic bacteria from extremely alkaline environments
Article first published online: 23 MAY 2011
© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd
Thematic Issue: Extremophiles. Guest Editors: Ricardo Cavicchioli, Ricardo Amils, Dirk Wagner, Terry McGenity
Volume 13, Issue 8, pages 2342–2350, August 2011
How to Cite
Lefèvre, C. T., Frankel, R. B., Pósfai, M., Prozorov, T. and Bazylinski, D. A. (2011), Isolation of obligately alkaliphilic magnetotactic bacteria from extremely alkaline environments. Environmental Microbiology, 13: 2342–2350. doi: 10.1111/j.1462-2920.2011.02505.x
- Issue published online: 21 AUG 2011
- Article first published online: 23 MAY 2011
- Received 13 February, 2011; accepted 4 April, 2011.
Large numbers of magnetotactic bacteria were discovered in mud and water samples collected from a number of highly alkaline aquatic environments with pH values of ∼ 9.5. These bacteria were helical in morphology and biomineralized chains of bullet-shaped crystals of magnetite and were present in all the highly alkaline sites sampled. Three strains from different sites were isolated and cultured and grew optimally at pH 9.0–9.5 but not at 8.0 and below, demonstrating that these organisms truly require highly alkaline conditions and are not simply surviving/growing in neutral pH micro-niches in their natural habitats. All strains grew anaerobically through the reduction of sulfate as a terminal electron acceptor and phylogenetic analysis, based on 16S rRNA gene sequences, as well as some physiological features, showed that they could represent strains of Desulfonatronum thiodismutans, a known alkaliphilic bacterium that does not biomineralize magnetosomes. Our results show that some magnetotactic bacteria can be considered extremophilic and greatly extend the known ecology of magnetotactic bacteria and the conditions under which they can biomineralize magnetite. Moreover, our results show that this type of magnetotactic bacterium is common in highly alkaline environments. Our findings also greatly influence the interpretation of the presence of nanometer-sized magnetite crystals, so-called magnetofossils, in highly alkaline environments.