Microbial Ecology of an Extreme Acidic Environment, the Tinto River

Abstract

The Tinto River (Huelva, southwestern Spain) is an extreme environment with a rather constant acidic pH along the entire river and a high concentration of heavy metals. The extreme conditions of the Tinto ecosystem are generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt. Molecular ecology techniques were used to analyze the diversity of this microbial community. The community's composition was studied by denaturing gradient gel electrophoresis (DGGE) using 16S rRNA and by 16S rRNA gene amplification. A good correlation between the two approaches was found. Comparative sequence analysis of DGGE bands showed the presence of organisms related to Leptospirillum spp., Acidithiobacillus ferrooxidans, Acidiphilium spp., "Ferrimicrobium acidiphilum," Ferroplasma acidiphilum, and Thermoplasma acidophilum. The different phylogenetic groups were quantified by fluorescent in situ hybridization with a set of rRNA-targeted oligonucleotide probes. More than 80% of the cells were affiliated with the domain Bacteria, with only a minor fraction corresponding to Archaea. Members of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, and Acidiphilium spp., all related to the iron cycle, accounted for most of the prokaryotic microorganisms detected. Different isolates of these microorganisms were obtained from the Tinto ecosystem, and their physiological properties were determined. Given the physicochemical characteristics of the habitat and the physiological properties and relative concentrations of the different prokaryotes found in the river, a model for the Tinto ecosystem based on the iron cycle is suggested.Microorganisms that are able to develop under extreme conditions have recently attracted considerable attention because of their peculiar physiology and ecology. These extremophiles also have important biotechnological applications (41,44,49,51). Acidic environments are especially interesting because, in general, the low pH of the habitat is the consequence of microbial metabolism (24) and not a condition imposed by the system as is the case in many other extreme environments (temperature, ionic strength, high pH, radiation, pressure, etc.). The Tinto River, a 100-km-long river in southwestern Spain, is an example of such an extreme acidic ecosystem; it has a low pH (between 1.5 and 3

First Prokaryotic Biodiversity Assessment Using Molecular Techniques of an Acidic River in Neuquén, Argentina

“…Cellular concentration was estimated at around 2.5×10 6 cell/ml along the river. This concentration is similar to those found on other acidic rivers [24], but higher from those reported for freeflowing waters of extreme acidic mine drainage (AMD) environments [16]. When analysing number of cells on sediments or mine tailing dumps, concentrations were higher [48].…”

“…There are a few natural environments with hydrothermal activity where acidic rivers originate; that is why they are so interesting to be studied. Microorganisms that inhabit those ecological niches are acidophilic, mesophilic or thermophilic, almost exclusively involved in iron and sulphur cycles [11,19,24], and are not found in neutral pH water rivers as they are unable to survive [12]. The effort put on revealing and understanding their biodiversity and ecology obeys to some other reasons than natural biologist interest on knowing what forms of life develop everywhere on Earth.…”

Profile of bacterial communities in South African mine-water samples using Illumina next-generation sequencing platform

“…Subsequently, some of the mine-water systems from different geographical locations were assayed using molecular techniques, e.g. Iron Mountain in California, USA (Bond et al 2000;Druschel et al 2004) and the Rio Tinto basin in southwestern Spain (Gonzalez-Toril et al 2003;Garcia-Moyano et al 2007). These studies, however, were based on a single mining environment, and only limited sequencing depths were achieved using a standard clone library approach.…”

Genome sequence of Picrophilus torridus and its implications for life around pH 0

“…A second group of thermoacidophiles can be found inside the crenarchaeal branch, the Sulfolobaceae. With only a few exceptions, members of both groups are aerobic or microaerophilic, heterotrophic organisms that are often found to share the same habitat (4)(5)(6). After analysis of a number of archaeal and bacterial genomes, it has been argued that microorganisms that live together swap genes at a higher frequency (7,8).…”