An endangered oasis of aquatic microbial biodiversity in the Chihuahuan desert

Abstract

The Cuatro Cienegas basin in the Chihuahuan desert is a system of springs, streams, and pools. These ecosystems support >70 endemic species and abundant living stromatolites and other microbial communities, representing a desert oasis of high biodiversity. Here, we combine data from molecular microbiology and geology to document the microbial biodiversity of this unique environment. Ten water samples from locations within the Cuatro Cienegas basin and two neighboring valleys as well as three samples of wet sediments were analyzed. The phylogeny of prokaryotic populations in the samples was determined by characterizing cultured organisms and by PCR amplification and sequencing of 16S rRNA genes from total community DNA. The composition of microbial communities was also assessed by determining profiles of terminal restriction site polymorphisms of 16S rRNA genes in total community DNA. There were 250 different phylotypes among the 350 cultivated strains. Ninety-eight partial 16S rRNA gene sequences were obtained and classified. The clones represented 38 unique phylotypes from ten major lineages of Bacteria and one of Archaea. Unexpectedly, 50% of the phylotypes were most closely related to marine taxa, even though these environments have not been in contact with the ocean for tens of millions of years. Furthermore, terminal restriction site polymorphism profiles and geological data suggest that the aquatic ecosystems of Cuatro Cienegas are hydrologically interconnected with adjacent valleys recently targeted for agricultural intensification. The findings underscore the conservation value of desert aquatic ecosystems and the urgent need for study and preservation of freshwater microbial communities.Cuatro Cienegas ͉ terminal restriction site polymorphism ͉ 16S clone library ͉ water conservation ͉ microbial ecology

Sedimentological imprint on subseafloor microbial communities in Western Mediterranean Sea Quaternary sediments

“…The long-term preservation of DNA and/or microorganisms has repeatedly, and sometimes controversially, been reported during the last decade, from various field data from different environments (e.g. halite, amber, sediments, evaporites, water samples) in facies as old as 100 million years (Fish et al, 2002;Inagaki et al, 2005;Souza et al, 2006). In 2005, Inagaki et al proposed that some molecular genetic reflections of the past may be somehow stored in a so-called "DNA Paleome" under specific conditions where degradations are minimized.…”

Genomics of Bacteria from an Ancient Marine Origin: Clues to Survival in an Oligotrophic Environment

“…This makes sense, given that the geological history of Cuatro Cienegas suggests that a shallow ocean covered the region and some of the water there is most likely a part of the underground water that feeds different ponds. This has led to the hypothesis that bacteria in the CCB water systems are descendants of marine bacteria from Pre-Cambrian (Souza et al 2006). Systematic studies have also been used to describe new species of bacteria using current criteria (Anderson et al 2005;Cerritos et al 2008;Ehling-Schulz et al 2005;Escalante et al 2009;Helgason et al 2004) as well as by attempting to apply multivariate analysis and physical-chemical analyses in order to determine special relationships amongst the bacteria (Cerritos et al 2011).…”

“…Thus, the high diversity of CCB would be a product of two things: the diversity already present at the time of isolation, and the new community assemblages that arose in this unique aquatic environment Souza et al 2006). Firmicutes, an abundant and widespread genera within CCB (Alcaraz et al 2010;Alcaraz et al 2008;Cerritos et al 2011;Moreno-Letelier et al 2011;Souza et al 2006) are the focal group of our studies, in part because there are several endemic species within the site, and because the whole genome has been sequenced for both Exiguobacterium and Bacillus isolates (Bacillus coahuilensis m4-4 ; Bacillus sp. m3-13 (Alcaraz et al 2010); and several unpublished data (from drafts Bacillus sp.…”

“…Several microbiological surveys have been carried out, including bacterial isolation and culturing, 16S rRNA gene amplification, genome sequencing, and metagenome sequencing. Characterization of the microbial taxonomic diversity by sequence analysis of the 16S rRNA genes directly from environmental DNA has revealed that nearly half of the phylotypes from the CCB are closely related to bacteria from marine environments (Souza et al 2006). This makes sense, given that the geological history of Cuatro Cienegas suggests that a shallow ocean covered the region and some of the water there is most likely a part of the underground water that feeds different ponds.…”

Cuatrociénegas: conflictos asociados al turismo en un área natural protegida

“…Cuatrocié-negas es un sitio de alta biodiversidad, con más de 70 especies endémicas de humedal, entre ellas peces, caracoles y bacterias. El sitio alberga 1,247 especies de fauna, 16 de las cuales están en peligro de extinción, 39 amenazadas y 34 bajo protección especial (Souza, et al, 2006;Escalante, et al, 2008;Lobo 2009 En el valle de Cuatrociénegas existen aproximadamente 500 cuerpos de agua superficiales conocidos localmente como pozas o ciénegas, los cuales brotan de manantiales con diámetros que van desde menos de un metro hasta más de cien, y profundidades de entre 50 centímetros y 18 metros. Algunas de las pozas se comunican natural o artificialmente entre sí mediante un complicado sistema de drenaje (INE, 1999;Conagua, 2009;Secretaría de Gobernación, 2008).…”