Metagenomic and Metabolic Analyses of Poly-Extreme Microbiome from an Active Crater Volcano Lake

Background: El Chichón volcano is one of the most active volcanoes in Mexico. Previous studies have described the poly-extreme conditions of the lake crater but its bacterial composition and the functional features of the complete microbiome have not been characterized yet. Methods: This study integrated two approaches to explain the microbiology diversity and abundance, one focused on the environmental genomic potential by metagenomics approach, and other culturomics of enrichment of bacteria and archaea. The microbial diversity of the anaerobic consortia cultivated in was carried out by metabarcoding analysis, the metabolic capacity by metabolomics fluxes of carbon and enzymologic techniques for the analysis of sulfate reduction in laboratory-grown prokaryotic cells. Results: This work provides new information on the taxonomic and functional diversity of the Archea representative phyla Crenarchaeota and Euryarchaeota as well as the phyla Thermotogales and Aquificae for Bacteria. Through the analysis of microbial consortia cultivation and the genetic information collected from the natural environment sampling, metabolic interactions were identified between the microorganisms that support the life of the microbiome under multi-extreme conditions. A close relationship is proposed between the cycles of carbon and sulfur in an active volcano. Conclusions: This research contributes to the understanding of microbial metabolism under extreme conditions and potential knowledge of "microbial dark matter" that can be applied in biotechnological processes and evolutionary studies.

Characterization of Thermophilic Microorganisms in the Geothermal Water Flow of El Chichón Volcano Crater Lake

This study reports for the first time the isolation, identification and characterization of lipase-producing thermophilic strain from the geothermal water of the El Chichón volcano crater lake. Two strains were identified by 16S rRNA sequencing as Geobacillus jurassicus CHI2 and Geobacillus stearothermophilus CHI1. Results showed that G. jurassicus CHI2 is Gram-positive, able to ferment maltose, fructose and sucrose and to hydrolyze starch and casein; while G. stearothermophilus CHI1 showed to be Gram-variable, able to ferment maltose and fructose and to hydrolyze starch. Colonies of both strains presented irregular shape, umbilicated elevation of gummy texture and cells presented flagellar movement to survive in fluids with high temperature and mass gradients due to complex phenomena of heat and mass transfer present in the geothermal fluids. Lipase production for G. stearothermophilus CHI1 was also evaluated. It was found that this strain possesses a growth associated with extracellular lipase production with a high activity of 143 U/mL at 8.3 h of incubation time, superior to the activities reported for other microorganisms of genus Geobacillus; for this reason, it can be said that the thermal flow of the El Chichón volcano crater lake can be a useful source of lipase-producing thermophilic bacteria.