Alicyclobacillus sp. SO9, a novel halophilic acidophilic iron-oxidizing bacterium isolated from a tailings-contaminated beach, and its effect on copper extraction from chalcopyrite in the presence of high chloride concentration.

Many acidophilic iron-oxidizing bacteria used in the mining industry for the bioleaching of sulfidic minerals are intolerant to high chloride concentrations, resulting in problems where chloride occurs in the deposit at high concentrations or only seawater is available. In search for strains tolerating such conditions a tetrathionate- and iron-oxidizing bacterium was isolated from a tailings-contaminated beach sample at Portman Bay, Cartagena-La Union mining district, Spain, in the presence of 20 g l (0.34 M) sodium chloride.

Shedding light on the electron transfer chain of a moderately acidophilic iron oxidizer: characterization of recombinant HiPIP-41, CytC-18 and CytC-78 derived from Ferrovum sp. PN-J47-F6.

Efficient electron transfer from the donor to the acceptor couple presents a necessary requirement for acidophilic and neutrophilic iron oxidizers due to the low energy yield of aerobic ferrous iron oxidation. Involved periplasmic electron carriers are very diverse in these bacteria and show adaptations to the respective thermodynamic constraints such as a more positive redox potential reported for extreme acidophilic Acidithiobacillus spp. Respiratory chain candidates of moderately acidophilic members of the genus Ferrovum share similarities with both their neutrophilic iron oxidizing relatives and the more distantly related Acidithiobacillus spp.

Transcriptomic analysis of chloride tolerance in Leptospirillum ferriphilum DSM 14647 adapted to NaCl.

Chloride ions are toxic for most acidophilic microorganisms. In this study, the chloride tolerance mechanisms in the acidophilic iron-oxidizing bacterium Leptospirillum ferriphilum DSM 14647 adapted to 180 mM NaCl were investigated by a transcriptomic approach. Results showed that 99 genes were differentially expressed in the adapted versus the non-adapted cultures, of which 69 and 30 were significantly up-regulated or down-regulated, respectively.

Metabolic history and metabolic fitness as drivers of anabolic heterogeneity in isogenic microbial populations.

Microbial populations often display different degrees of heterogeneity in their substrate assimilation, that is, anabolic heterogeneity. It has been shown that nutrient limitations are a relevant trigger for this behaviour. Here we explore the dynamics of anabolic heterogeneity under nutrient replete conditions.

Secondary metabolites released by the rhizosphere bacteria Arthrobacter oxydans and Kocuria rosea enhance plant availability and soil-plant transfer of germanium (Ge) and rare earth elements (REEs).

Here, we explore effects of metallophore-producing rhizobacteria on the plant availability of germanium (Ge) and rare earth elements (REEs). Five isolates of the four species Rhodococcus erythropolis, Arthrobacter oxydans, Kocuria rosea and Chryseobacterium koreense were characterized regarding their production of element-chelators using genome-mining, LC-MS/MS analysis and solid CAS-assay. Additionally, a soil elution experiment was conducted in order to identify isolates that increase solubility of Ge and REEs in soil solution.

Isolation and characterization of arsenic-binding siderophores from Rhodococcus erythropolis S43: role of heterobactin B and other heterobactin variants.

Rhodococcus erythropolis S43 is an arsenic-tolerant actinobacterium isolated from an arsenic contaminated soil. It has been shown to produce siderophores when exposed to iron-depleting conditions. In this work, strain S43 was shown to have the putative heterobactin production cluster htbABCDEFGHIJ(K).

Biochemical Characterization of Phenylacetaldehyde Dehydrogenases from Styrene-degrading Soil Bacteria.

Four phenylacetaldehyde dehydrogenases (designated as FeaB or StyD) originating from styrene-degrading soil bacteria were biochemically investigated. In this study, we focused on the Michaelis-Menten kinetics towards the presumed native substrate phenylacetaldehyde and the obviously preferred co-substrate NAD. Furthermore, the substrate specificity on four substituted phenylacetaldehydes and the co-substrate preference were studied.

Effect of Sodium Chloride on Pyrite Bioleaching and Initial Attachment by .

Biomining applies microorganisms to extract valuable metals from usually sulfidic ores. However, acidophilic iron (Fe)-oxidizing bacteria tend to be sensitive to chloride ions which may be present in biomining operations. This study investigates the bioleaching of pyrite (FeS), as well as the attachment to FeS by DSM 9293 in the presence of elevated sodium chloride (NaCl) concentrations.

Effect of inoculum history, growth substrates and yeast extract addition on inhibition of Sulfobacillus thermosulfidooxidans by NaCl.

This study reports on the effect of inoculum history, growth substrates, and yeast extract on sodium chloride tolerance of Sulfobacillus thermosulfidooxidans DSM 9293. The concentrations of NaCl for complete inhibition of Fe oxidation by cells initially grown with ferrous iron sulfate, or tetrathionate, or pyrite as energy sources were 525 mM, 725 mM, and 800 mM, respectively. Noticeably, regardless of NaCl concentrations, oxygen consumption rates of S.

Cultivation dependent formation of siderophores by Gordonia rubripertincta CWB2.

Herein we demonstrate cultivation-dependent siderophore production by the actinomycete Gordonia rubripertincta CWB2. The strain produces mostly citrate, but also desferrioxamine E (DFOE) and new hydroxamate-type siderophores. The production of hydroxamate-like siderophores is influenced by cultivation conditions, for example available carbon sources or presence of metals, such as the rare earth erbium or the heavy metal lead.

Data on metal-chelating, -immobilisation and biosorption properties by CWB2 in dependency on rare earth adaptation.

Recent studies have shown that the metal adaptation of Actinobacteria offers a rich source of metal inducible environmentally relevant bio-compounds and molecules. These interact through biosorption towards the unique cell walls or via metal chelating activity of metallophors with trace elements, heavy metals and even with lanthanides to overcome limitations and toxic concentrations. Herein, the purpose is to investigate the adaptation potential of CWB2 in dependence of the rare earths and to determine if we can utilize promising metallophore metal affinities for metal separation from aquatic solutions.

Quantitation and Comparison of Phenotypic Heterogeneity Among Single Cells of Monoclonal Microbial Populations.

Phenotypic heterogeneity within microbial populations arises even when the cells are exposed to putatively constant and homogeneous conditions. The outcome of this phenomenon can affect the whole function of the population, resulting in, for example, new "adapted" metabolic strategies and impacting its fitness at given environmental conditions. Accounting for phenotypic heterogeneity becomes thus necessary, due to its relevance in medical and applied microbiology as well as in environmental processes.

Osmotic Imbalance, Cytoplasm Acidification and Oxidative Stress Induction Support the High Toxicity of Chloride in Acidophilic Bacteria.

In acidophilic microorganisms, anions like chloride have higher toxicity than their neutrophilic counterparts. In addition to the osmotic imbalance, chloride can also induce acidification of the cytoplasm. We predicted that intracellular acidification produces an increase in respiratory rate and generation of reactive oxygen species, and so oxidative stress can also be induced.

Investigation of the co-metabolic transformation of 4-chlorostyrene into 4-chlorophenylacetic acid in ST.

The side-chain oxygenation of styrene is able to yield substituted phenylacetic acids from corresponding styrenes by co-metabolic transformation. This co-metabolization was investigated in ST using 4-chlorostyrene as co-substrate. It was shown that non-substituted styrene is necessary to ensure the co-metabolic process.

Draft genome sequence of Rhodococcus erythropolis B7g, a biosurfactant producing actinobacterium.

Biosurfactants are amphipathic molecules with relevance in biotechnology due to their structural diversity, low toxicity and biodegradability. The genus Rhodococcus has extensively been studied because of its capacity to produce trehalose-containing surfactants as well as trehalose lipids as potential pathogenic factor. Here we present the draft genome sequence of Rhodococcus erythropolis B7g isolated with toluene from fuel-contaminated soil.

Iron targeted transcriptome study draws attention to novel redox protein candidates involved in ferrous iron oxidation in "Ferrovum" sp. JA12.

The response of the acidophilic iron oxidizer "Ferrovum" sp. JA12 to elevated concentrations of ferrous iron was targeted at transcriptome level in order to assess models on oxidative stress management and ferrous iron oxidation. Overall transcriptome profiles indicate a high cellular activity of "Ferrovum" sp.

Detection of arsenic-binding siderophores in arsenic-tolerating Actinobacteria by a modified CAS assay.

The metalloid arsenic is highly toxic to all forms of life, and in many countries decontamination of water and soil is still required. Some bacteria have mechanisms to detoxify arsenic and can live in its presence. Actinobacteria are well known for their ability to produce a myriad of biologically-active compounds.

Draft Genome of the Heterotrophic Iron-Oxidizing Bacterium "" Huett2, Isolated from a Mine Drainage Ditch in Freiberg, Germany.

Here, we communicate the draft genome of "" Huett2, a novel strain of an acidophilic, heterotrophic, iron-oxidizing bacterium belonging to the phylum It was isolated from a water drainage system of a former minefield in Freiberg, Germany.

Heterologous production of different styrene oxide isomerases for the highly efficient synthesis of phenylacetaldehyde.

The styrene oxide isomerase (SOI, StyC) represents a key enzyme of the styrene-degrading pathway and has been discussed as promising biocatalyst during recent studies. The enzyme enables the synthesis of pure phenylacetaldehyde from styrene oxide. In this study the native as well as the corresponding codon-optimized genes of three different SOIs from Rhodococcus opacus 1CP (StyC-1CP), Sphingopyxis fribergensis Kp5.

Microbial diversity of the hypersaline and lithium-rich Salar de Uyuni, Bolivia.

Salar de Uyuni, situated in the Southwest of the Bolivian Altiplano, is the largest salt flat on Earth. Brines of this athalassohaline hypersaline environment are rich in lithium and boron. Due to the ever- increasing commodity demand, the industrial exploitation of brines for metal recovery from the world's biggest lithium reservoir is likely to increase substantially in the near future.

Reconstruction of the Metabolic Potential of Acidophilic Strains from the Metagenome of an Microaerophilic Enrichment Culture of Acidophilic Iron-Oxidizing Bacteria from a Pilot Plant for the Treatment of Acid Mine Drainage Reveals Metabolic Versatility and Adaptation to Life at Low pH.

Bacterial community analyses of samples from a pilot plant for the treatment of acid mine drainage (AMD) from the lignite-mining district in Lusatia (East Germany) had previously demonstrated the dominance of two groups of acidophilic iron oxidizers: the novel candidate genus "" and a group comprising -like strains. Since pure culture had proven difficult, previous studies have used genome analyses of co-cultures consisting of "" and a strain of the heterotrophic acidophile in order to obtain insight into the life style of these novel bacteria. Here we report on attempts to undertake a similar study on -like acidophiles from AMD.

Characterization of Aldehyde Dehydrogenases Applying an Enzyme Assay with In Situ Formation of Phenylacetaldehydes.

Herein, different dehydrogenases (DH) were characterized by applying a novel two-step enzyme assay. We focused on the NAD(P)-dependent phenylacetaldehyde dehydrogenases because they produce industrially relevant phenylacetic acids, but they are not well studied due to limited substrate availability. The first assay step comprises a styrene oxide isomerase (440 U mg) which allows the production of pure phenylacetaldehydes (>70 mmol L) from commercially available styrene oxides.

Engineering Styrene Monooxygenase for Biocatalysis: Reductase-Epoxidase Fusion Proteins.

The enantioselective epoxidation of styrene and related compounds by two-component styrene monooxygenases (SMOs) has targeted these enzymes for development as biocatalysts. In the present work, we prepare genetically engineered fusion proteins that join the C-terminus of the epoxidase (StyA) to the N-terminus of the reductase (StyB) through a linker peptide and demonstrate their utility as biocatalysts in the synthesis of Tyrain purple and other indigoid dyes. A single-vector expression system offers a simplified platform for transformation and expansion of the catalytic function of styrene monooxygenases, and the resulting fusion proteins are self-regulated and couple efficiently NADH oxidation to styrene epoxidation.

A thermophilic-like ene-reductase originating from an acidophilic iron oxidizer.

Ene-reductases originating from extremophiles are gaining importance in the field of biocatalysis due to higher-stability properties. The genome of the acidophilic iron-oxidizing bacterium "Ferrovum" sp. JA12 was found to harbor a thermophilic-like ene-reductase (FOYE-1).

Gene Loss and Horizontal Gene Transfer Contributed to the Genome Evolution of the Extreme Acidophile "Ferrovum".

Acid mine drainage (AMD), associated with active and abandoned mining sites, is a habitat for acidophilic microorganisms that gain energy from the oxidation of reduced sulfur compounds and ferrous iron and that thrive at pH below 4. Members of the recently proposed genus "Ferrovum" are the first acidophilic iron oxidizers to be described within the Betaproteobacteria. Although they have been detected as typical community members in AMD habitats worldwide, knowledge of their phylogenetic and metabolic diversity is scarce.