Isolation of obligately alkaliphilic magnetotactic bacteria from extremely alkaline environments

TitleIsolation of obligately alkaliphilic magnetotactic bacteria from extremely alkaline environments
Publication TypeJournal Article
Year of Publication2011
AuthorsLefevre CT, Frankel RB, Posfai M, Prozorov T, Bazylinski DA
Journal TitleEnvironmental Microbiology
Volume13
Pages2342-2350
Date Published08
Type of ArticleArticle
ISBN Number1462-2912
Accession NumberWOS:000294075600032
Keywordscalifornia, dissimilatory arsenate reduction, growth, magnetosome formation, mono lake, prokaryotes, shallow-water carbonates, soda lakes, sp nov., sulfate-reducing bacterium
Abstract

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 similar to 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.

DOI10.1111/j.1462-2920.2011.02505.x
Alternate JournalEnviron. Microbiol.