Production of Glycolic Acid by Chemolithotrophic Iron- and Sulfur-Oxidizing Bacteria and Its Role in Delineating and Sustaining Acidophilic Sulfide Mineral-Oxidizing Consortia (original) (raw)
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Applied and Environmental Microbiology, 2007
A novel species of Acidimicrobium appeared to be the predominant ferrous iron oxidizer in a mixed culture that effected the continuous, efficient extraction of nickel from a mineral concentrate at 49°C, but it was not isolated in pure culture. It outcompeted Acidimicrobium ferrooxidans, which was expected to have a major role in iron oxidation in reactors gassed with air, and was outnumbered at 49°C only by the sulfur-oxidizing Acidithiobacillus caldus. Sulfobacillus species were expected to compete with Acidimicrobium species when culture aeration was enriched with carbon dioxide, but they were a minor component of the populations with and without this enrichment. Sulfobacillus thermosulfidooxidans replaced the Acidimicrobium species and Acidithiobacillus caldus when the temperature was increased to 55°C.
Biodiversity and ecology of acidophilic microorganisms
FEMS Microbiology Ecology, 1998
Microbial life in extremely low pH (6 3) natural and man-made environments may be considerably diverse. Prokaryotic acidophiles (eubacteria and archaea) have been the focus of much of the research activity in this area, primarily because of the importance of these microorganisms in biotechnology (predominantly the commercial biological processing of metal ores) and in environmental pollution (genesis of`acid mine drainage'); however, obligately acidophilic eukaryotes (fungi, yeasts, algae and protozoa) are also known, and may form stable microbial communities with prokaryotes, particularly in lower temperature (6 35³C) environments. Primary production in acidophilic environments is mediated by chemolitho-autotrophic prokaryotes (iron and sulfur oxidisers), and may be supplemented by phototrophic acidophiles (predominantly eukaryotic microalgae) in illuminated sites. The most thermophilic acidophiles are archaea (Crenarchaeota) whilst in moderately thermal (40^60³C) acidic environments archaea (Euryarchaeota) and bacteria (mostly Gram-positives) may co-exist. Lower temperature (mesophilic) extremely acidic environments tend to be dominated by Gram-negative bacteria, and there is recent evidence that mineral oxidation may be accelerated by acidophilic bacteria at very low (ca. 0³C) environments. Whilst most acidophiles have conventionally been considered to be obligately aerobic, there is increasing evidence that many isolates are facultative anaerobes, and are able to couple the oxidation of organic or inorganic electron donors to the reduction of ferric iron. A variety of interactions have been demonstrated to occur between acidophilic microorganisms, as in other environments ; these include competition, predation, mutualism and synergy. Mixed cultures of acidophiles are frequently more robust and efficient (e.g. in oxidising sulfide minerals) than corresponding pure cultures. In view of the continuing expansion of microbial mineral processing (`biomining') as a cost-effective and environmentally sensitive method of metal extraction, and the ongoing concern of pollution from abandoned mine sites, acidophilic microbiology will continue to be of considerable research interest well into the new millennium.
Proceedings of the Institute of Biology, Romanian Academy, Bucharest, 2002
The study of the research regarding the acidophilic procaryote microorganisms (eubacteria and archaea) is very new because of the importance of these microorganisms in biotechnology and in the depollution of the environment. The growth and activity of bacteria in the acidic biotopes depend greatly on the ecological conditions of the environment. Through their activity the acidophilic bacteria determine changes of the environment pH and of the oxido-reduction potential and during their metabolism, they can elaborate different useful substances, which have complex oxidizing or reductive properties. The acidity influences in a different way the life and activity of the different types of microorganisms present in low pH media. In this context, this paper presents the effects of acidity in static and continuous agitation conditions on the growth and activity of the acidophilic chemolithotrophic sulphur-oxidizing bacteria, isolated from the acidic mining effluents from two mines: Baia and Valea Şesei.
Microbiology, 1996
Several isolates of Gram-positive, acidophik, moderately thermophilic, ferrous-iron-and mineral-sulphide-oxidizing bacteria were examined to establish unequivocally the characteristics of Sulfobacillus-like bacteria. Two species were evident : Sulfobacillus thermosulfidooxidans with 48-50 mol O/ O G + C and Sulfobacillus acidophilus sp. nov. with 55-57 mol O/ O G + C. Both species grew autotrophically and mixotrophically on ferrous iron, on elemental sulphur in the presence of yeast extract, and heterotrophically on yeast extract. Autotrophic growth on sulphur was consistently obtained only with S. acidophilus.
FEMS microbiology letters, 2016
Growth media have been developed to facilitate the enrichment and isolation of acidophilic and acid-tolerant sulfate reducing bacteria (aSRB) from environmental and industrial samples, and to allow their cultivationin vitro The main features of the "standard" solid and liquid devised media are: (i) use of glycerol rather than an aliphatic acid as electron donor; (ii) inclusion of stoichiometric concentrations of zinc ions to both buffer pH and to convert potentially harmful hydrogen sulfide produced by the aSRB to insoluble zinc sulfide; (ii) inclusion ofAcidocella aromatica(an heterotrophic acidophile that does not metabolize glycerol or yeast extract) in the gel underlayer of double layered (overlay) solid media, to remove acetic acid produced by aSRB that incompletely oxidize glycerol and also aliphatic acids (mostly pyruvic) released by acid hydrolysis of the gelling agent used (agarose). Colonies of aSRB are readily distinguished from those of other anaerobes due to t...
Extremophiles, 2009
Phenotypic and genotypic analysis was carried out on four iron-and sulfur-oxidizing acidophilic bacteria (the ''NO-37 group'') isolated from different parts of the world. 16S rRNA phylogeny showed that they are highly related to each other, but are less related to the type strain of Acidithiobacillus ferrooxidans. The NO-37 group isolates are obligate chemolithoautotrophs, facultative anaerobes, diazotrophic, and psychrotolerant. They are less tolerant of extremely low pH, and in contrast to At. ferrooxidans T , all of the NO-37 group isolates are motile. The GC contents of genomic DNA of the NO-37 group isolates were around 56 mol% and the DNA-DNA hybridization value between genomic DNA of isolate NO-37 and At. ferrooxidans T was 37%. It also appears that the bacteria of the NO-37 group have a different biochemical mechanism for oxidizing ferrous iron than At. ferrooxidans T ; the gene coding for the archetypal rusticyanin (RusA) was not detected in any of the NO-37 group isolates, rather a gene coding for a homologous protein (RusB) was amplified from three of the four novel isolates. Isolates of the NO-37 group clearly belong to a species that is different to those already recognized in the genus Acidithiobacillus, for which the name Acidithiobacillus ferrivorans is proposed. Keywords Acid mine drainage Á Acidophile Á Acidithiobacillus Á Bioleaching Á Biomining Á Iron Á Pyrite Á Psychrotolerant bacteria Á Sulfur Communicated by T. Matsunaga.
2009
Mesophilic iron and sulfur-oxidizing acidophiles are readily found in acid mine drainage sites and bioleaching operations, but relatively little is known about their activities at suboptimal temperatures and in cold environments. The purpose of this work was to characterize the oxidation of elemental sulfur (S 0), tetrathionate (S 4 O 6 2À) and ferrous iron (Fe 2þ) by the psychrotolerant Acidithiobacillus strain SS3. The rates of elemental sulfur and tetrathionate oxidation had temperature optima of 20 and 25 C, respectively, determined using a temperature gradient incubator that involved narrow (1.1 C) incremental increases from 5 to 30 C. Activation energies calculated from the Arrhenius plots were 61 and 89 kJ mol À1 for tetrathionate and 110 kJ mol À1 for S 0 oxidation. The oxidation of elemental sulfur produced sulfuric acid at 5 C and decreased the pH to approximately 1. The low pH inhibited further oxidation of the substrate. In media with both S 0 and Fe 2þ , oxidation of elemental sulfur did not commence until all available ferrous iron was oxidized. These data on sequential oxidation of the two substrates are in keeping with upregulation and downregulation of several proteins previously noted in the literature. Ferric iron was reduced to Fe 2þ in parallel with elemental sulfur oxidation, indicating the presence of a sulfur:ferric iron reductase system in this bacterium.
Transactions of Nonferrous Metals Society of China, 2008
Mining companies have become increasingly aware of the potential of microbiological approaches for recovering base and precious metals from low-grade ores, and for remediating acidic, metal-rich wastewaters that drain from both operating and abandoned mine sites. Biological systems offer a number of environmental and (sometimes) economical advantages over conventional approaches, such as pyrometallurgy, though their application is not appropriate in every situation. Mineral processing using microorganisms has been exploited for extracting gold, copper, uranium and cobalt, and current developments are targeting other base metals. Recently, there has been a great increase in our knowledge and understanding of both the diversity of the microbiology of biomining environments, and of how the microorganisms interact with each other. The results from laboratory experiments which have simulated both stirred tank and heap bioreactor systems have shown that microbial consortia are more robust than pure cultures of mineral-oxidizing acidophiles, and also tend to be more effective at bioleaching and bio-oxidizing ores and concentrates. The paper presented a concise review of the nature and interactions of microbial consortia that are involved in the oxidation of sulfide minerals, and how these might be adapted to meet future challenges in biomining operations.