Bacterial diversity in fumarole environments of the Paricutín volcano, Michoacán (Mexico).

Active volcanoes are among the most extreme environments on Earth. The extreme temperatures, presence of toxic heavy metals and low nutrient bioavailability favor the development of extremophiles. We characterized the physical-chemical parameters of and bacterial communities (T-RFLP and 16S rRNA gene libraries) inhabiting fumarole niches of the Paricutín volcano located in Michoacán (Mexico). This volcano, which surged in 1943, is one of the youngest volcanoes on Earth and the microbial diversity in this area is yet to be characterized. The sampling stations were characterized in a pH range from 5.34 to 7.89 and showed different temperatures (soil, 27-87 °C; air, 13.6-56 °C) with high concentrations of metals such as iron and arsenic. The most abundant bacterial populations, confirmed by T-RFLP and 16S rRNA gene libraries, were related to members of Firmicutes and Proteobacteria phyla including sequences associated with thermophiles and sulfate reducing bacteria. Overall, the Paricutín volcano showed low bacterial diversity and its prokaryotic diversity was characterized by the impossibility of amplifying Archaea-related sequences.