Diversity of culturable thermo-resistant aquatic bacteria along an environmental gradient in Cuatro Ciénegas, Coahuila, México

Abstract

At the desert oasis of Cuatro Ciénegas in Coahuila, México, more than 300 oligotrophic pools can be found and a large number of endemic species of plants and animals. The most divergent taxa of diatoms, snail and fishes are located in the Churince hydrological system, where we analyzed the local diversification of cultivable Firmicutes and Actinobacteria. The Churince hydrological system is surrounded by gypsum dunes and has a strong gradient for salinity, temperature, pH and dissolved oxygen. In August 2003, surface water samples were taken in 10 sites along the Churince system together with the respective environmental measurements. 417 thermo-resistant bacteria were isolated and DNA was extracted to obtain their BOX-PCR fingerprints, revealing 55 different patterns. In order to identify similarities and differences in the diversity of the various sampling sites, an Ordination Analysis was applied using Principal Component Analysis. This analysis showed that conductivity is the environmental factor that explains the distribution of most of the microbial diversity. Phylogenetic reconstruction from their 16S rRNA sequences was performed for a sample of 150 isolates. Only 17 sequences had a 100% match in the Gene Bank (NCBI), representing 10 well known cosmopolitan taxa. The rest of the sequences cluster in 22 clades for Firmicutes and another 22 clades for Actinobacteria, supporting the idea of high diversity and differentiation for this site.

Evaluating the Diversity of Culturable Thermotolerant Bacteria from Four Hot Springs of India

“…Schuman et al [30] suggested that Cellulomonas should be reclassified as Cellulosimicrobium. Cellulomonas has previously been reported as a culturable thermoresistant aquatic bacterium from the oligotrophic pools in Mexico [27]. To our knowledge, this is the first report on Aurantimonas and Brevundimonas in a hot spring.…”

“…Among the different genera obtained from Vashist hot springs Exiguobacterium, Kocuria and Brevibacillus were reported in our earlier study on diversity of thermotolerant bacteria from Manikaran [21] and also in the studies on the diversity of culturable thermoresistant aquatic bacteria in Mexico [27]. Representatives from Acinetobacter, Enterobacter and Gulbenkiania, which are pathogens and associated with human intestine, may have been transmitted as contaminants from people taking shower in the spring, as this spring is known for its medicinal properties.…”

“…Another commonality in these four hot springs is the presence of isolates belonging to Actinobacteria. Gram positive prokaryotes are known to be comparatively stress resistant and long range migrants, especially the Firmicutes and Actinobacteria [27].…”

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

“…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). At the genomic scale, 2 genomes (Alcaraz et al 2010;Alcaraz et al 2008) and 3 metagenomes (Breitbart et al 2009;Desnues et al 2008;Dinsdale et al 2008) had been described, in which genes that allow for adaptation to the oligotrophic environment of Cuatro Cienegas have been identified.…”

“…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.…”