Fungal Alcohol Dehydrogenases: Physiological Function, Molecular Properties, Regulation of Their Production, and Biotechnological Potential.

Fungal alcohol dehydrogenases (ADHs) participate in growth under aerobic or anaerobic conditions, morphogenetic processes, and pathogenesis of diverse fungal genera. These processes are associated with metabolic operation routes related to alcohol, aldehyde, and acid production. The number of ADH enzymes, their metabolic roles, and their functions vary within fungal species.

Secretion of the siderophore rhizoferrin is regulated by the cAMP-PKA pathway and is involved in the virulence of Mucor lusitanicus.

Mucormycosis is a fungal infection caused by Mucorales, with a high mortality rate. However, only a few virulence factors have been described in these organisms. This study showed that deletion of rfs, which encodes the enzyme for the biosynthesis of rhizoferrin, a siderophore, in Mucor lusitanicus, led to a lower virulence in diabetic mice and nematodes.

Aerobic processes for bioleaching manganese and silver using microorganisms indigenous to mine tailings.

Mining wastes containing appreciable concentrations of silver are considered alternative sources for metal extraction, although these wastes are often refractory due to the presence of manganese oxides. The high cost and/or environmental impact of the hydrometallurgical and pyrometallurgical extraction processes make it necessary to search for biotechnological processes for the solubilization of manganese compounds. This paper describes the characterization of chemoorganotrophic microorganisms indigenous to the tailings of a silver mine located in Coahuila, México, regarding their capability to remove manganese and silver present in these residues by lixiviation.

Hidden Costs in the Physiology of Argia anceps (Zigoptera: Coenagrionidae) due to Pollution.

Before a population becomes extinct, there are hidden costs in the physiology at the individual level that provide valuable insights into their condition. Here, we study two dams with one species in common (Argia anceps Garrison, 1996) to evaluate whether their physiological condition differed (total protein quantity, prophenoloxidase (proPO) and phenoloxidase (PO) activity, and protein carbonylation) during two consecutive years. The first dam, "El Gallinero" (contaminated, C), contains organic input from mines and agricultural activity, whereas the second, "Paso de Vaqueros" (non-contaminated, NC), is part of a biosphere reserve.

Alteration of Fermentative Metabolism Enhances Mucor circinelloides Virulence.

The fungus undergoes yeast-mold dimorphism, a developmental process associated with its capability as a human opportunistic pathogen. Dimorphism is strongly influenced by carbon metabolism, and hence the type of metabolism likely affects fungus virulence. We investigated the role of ethanol metabolism in virulence.

Alcohol dehydrogenase 1 participates in the Crabtree effect and connects fermentative and oxidative metabolism in the Zygomycete Mucor circinelloides.

Mucor circinelloides is a dimorphic Zygomycete fungus that produces ethanol under aerobic conditions in the presence of glucose, which indicates that it is a Crabtree-positive fungus. To determine the physiological role of the alcohol dehydrogenase (ADH) activity elicited under these conditions, we obtained and characterized an allyl alcohol-resistant mutant that was defective in ADH activity, and examined the effect of adh mutation on physiological parameters related to carbon and energy metabolism. Compared to the Adh strain R7B, the ADH-defective (Adh) strain M5 was unable to grow under anaerobic conditions, exhibited a considerable reduction in ethanol production in aerobic cultures when incubated with glucose, had markedly reduced growth capacity in the presence of oxygen when ethanol was the sole carbon source, and exhibited very low levels of NAD-dependent alcohol de-hydrogenase activity in the cytosolic fraction.

Impact of Cr(VI) on the oxidation of polyunsaturated fatty acids in Helianthus annuus roots studied by metabolomic tools.

The impact of Cr(VI) in sunflower roots has been studied, focusing on the oxidation of polyunsaturated fatty acids. Plants were grown hydroponically in the presence of 0, 1.0, 5.

CrpP Is a Novel Ciprofloxacin-Modifying Enzyme Encoded by the Pseudomonas aeruginosa pUM505 Plasmid.

The pUM505 plasmid, isolated from a clinical isolate, confers resistance to ciprofloxacin (CIP) when transferred into the standard strain PAO1. CIP is an antibiotic of the quinolone family that is used to treat infections. analysis, performed to identify CIP resistance genes, revealed that the 65-amino-acid product encoded by the gene in pUM505 displays 40% amino acid identity to the aminoglycoside phosphotransferase (an enzyme that phosphorylates and inactivates aminoglycoside antibiotics).

Changes of Metabolomic Profile in under Exposure to Chromium(VI) Studied by capHPLC-ESI-QTOF-MS and MS/MS.

The application of capHPLC-ESI-QTOF-MS and MS/MS to study the impact of Cr(VI) on metabolites profile in is reported. Germinated seeds were grown hydroponically in the presence of Cr(VI) (25 mgCr/L) and root extracts of the exposed and control plants were analyzed by untargeted metabolomic approach. The main goal was to detect which metabolite groups were mostly affected by Cr(VI) stress; two data analysis tools (ProfileAnalysis, Bruker, and online XCMS) were used under criteria of intensity threshold 5 · 10 cps, fold change ≥ 5, and ≤ 0.

Microbial interactions with chromium: basic biological processes and applications in environmental biotechnology.

Chromium (Cr) is a highly toxic metal for microorganisms as well as plants and animal cells. Due to its widespread industrial use, Cr has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form.

Cr(VI) reduction by gluconolactone and hydrogen peroxide, the reaction products of fungal glucose oxidase: Cooperative interaction with organic acids in the biotransformation of Cr(VI).

The Cr(VI) reducing capability of growing cells of the environmental A. tubingensis Ed8 strain is remarkably efficient compared to reference strains A. niger FGSC322 and A.

Role of Bacillus subtilis error prevention oxidized guanine system in counteracting hexavalent chromium-promoted oxidative DNA damage.

Chromium pollution is potentially detrimental to bacterial soil communities, compromising carbon and nitrogen cycles that are essential for life on earth. It has been proposed that intracellular reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] may cause bacterial death by a mechanism that involves reactive oxygen species (ROS)-induced DNA damage; the molecular basis of the phenomenon was investigated in this work. Here, we report that Bacillus subtilis cells lacking a functional error prevention oxidized guanine (GO) system were significantly more sensitive to Cr(VI) treatment than cells of the wild-type (WT) strain, suggesting that oxidative damage to DNA is involved in the deleterious effects of the oxyanion.

Mechanisms of interaction of chromium with Aspergillus niger var tubingensis strain Ed8.

Experiments were conducted to determine the mechanisms of interaction with chromium of Aspergillus niger var tubingensis strain Ed8 in batch culture and in bioreactor experiments. Results obtained in this work showed that the interaction of A. niger var tubingensis Ed8 with Cr(VI) is based mainly in a reduction process and also, secondly, in a sorption process.

Bacterial biodiversity from anthropogenic extreme environments: a hyper-alkaline and hyper-saline industrial residue contaminated by chromium and iron.

Anthropogenic extreme environments are among the most interesting sites for the bioprospection of extremophiles since the selection pressures may favor the presence of microorganisms of great interest for taxonomical and astrobiological research as well as for bioremediation technologies and industrial applications. In this work, T-RFLP and 16S rRNA gene library analyses were carried out to describe the autochthonous bacterial populations from an industrial waste characterized as hyper-alkaline (pH between 9 and 14), hyper-saline (around 100 PSU) and highly contaminated with metals, mainly chromium (from 5 to 18 g kg(-1)) and iron (from 2 to 108 g kg(-1)). Due to matrix interference with DNA extraction, a protocol optimization step was required in order to carry out molecular analyses.

Fusarium oxysporum Adh1 has dual fermentative and oxidative functions and is involved in fungal virulence in tomato plants.

An alcohol dehydrogenase gene, adh1, has been identified in the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici.

Effect of Fusarium oxysporum f. sp. lycopersici on the soil-to-root translocation of heavy metals in tomato plants susceptible and resistant to the fungus.

The purpose of this work was to gain an insight on the potential role of the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici in the translocation of metals and metalloids from soil to plant roots in tomato (Lycopersicum esculentum).

Hexavalent chromium reduction by bacterial consortia and pure strains from an alkaline industrial effluent.

Aims: To characterize the bacterial consortia and isolates selected for their role in hexavalent chromium removal by adsorption and reduction.

Methods And Results: Bacterial consortia from industrial wastes revealed significant Cr(VI) removal after 15 days when incubated in medium M9 at pH 6·5 and 8·0. The results suggested chromium reduction.

Effect of Fusarium oxysporum f. sp. lycopersici on the degradation of humic acid associated with Cu, Pb, and Ni: an in vitro study.

The intent of this work was to gain further insight on the fungus-assisted degradation/solubilization of humic acid and the related changes in metal-binding profiles. In the experimental design, Aldrich reagent humic acid (HA) or HA enriched with Cu, Pb, and Ni (HA(Me)) was added to Fusarium oxysporum f. sp.

Cr(VI) reduction by an Aspergillus tubingensis strain: role of carboxylic acids and implications for natural attenuation and biotreatment of Cr(VI) contamination.

Experiments conducted in shake flask cultures, in minimal medium of pH 5.3 containing 50 microg mL(-1)Cr(VI) with glucose as a carbon source, indicated that the biomass of Aspergillus sp. strain Ed8, a chromate-tolerant fungal strain previously isolated from a chromium-polluted soil, responds to the presence of citrate in the medium by increasing the rate of Cr(VI) reduction; this effect required the use of live biomass and was not observed in medium with lactate.

Analytical speciation of chromium in in-vitro cultures of chromate-resistant filamentous fungi.

In this work, different analytical speciation schemes have been used to study the reduction of Cr(VI) by a chromate-resistant strain of filamentous fungi Ed8 (Aspergillus sp), indigenous to contaminated industrial wastes. As demonstrated previously, this strain has the capability to reduce chromate present in the growth medium without its accumulation in the biomass, yet the reduced chromium end-products have not been characterized. Liquid growth medium, initially containing 50 mg L(-1) Cr(VI), was analyzed for Cr(III)/Cr(VI) and for total Cr at different time intervals (0-24 h) after inoculation with fungi.

[Microbial interactions with heavy metals].

Living organisms are exposed in nature to heavy metals, commonly present in their ionized species. These ions exert diverse toxic effects on microorganisms. Metal exposure both selects and maintains microbial variants able to tolerate their harmful effects.

The protective effect of selenium inorganic forms against cadmium and silver toxicity in mycelia of Pleurotus ostreatus.

The effect of two inorganic selenium forms has been investigated in the mycelia of Pleurotus ostreatus exposed to cadmium and silver salts in the shaken cultures. The degree of toxicity was assessed by the determination of malondialdehyde (MDA; a common biomarker of lipid peroxidation). The mycelia were exposed to one element form (up to 5 mg l(-1)) and also to the following combinations: cadmium(II) + selenium(IV); cadmium(II) + selenium(VI); silver(I) + selenium(IV); silver(I) + selenium(VI).

Hexavalent chromium removal in vitro and from industrial wastes, using chromate-resistant strains of filamentous fungi indigenous to contaminated wastes.

Two chromate-resistant filamentous fungi, strains H13 and Ed8, were selected from seven independent fungal isolates indigenous to Cr(VI)-contaminated soil because of their ability to decrease hexavalent chromium levels in the growth medium. Morphophysiological studies identified strain H13 as a Penicillium sp. isolate and Ed8 as an Aspergillus sp.

Se-enriched mycelia of Pleurotus ostreatus: distribution of selenium in cell walls and cell membranes/cytosol.

The incorporation of Se to fungi has been studied, focusing on element distribution among different cellular compartments and, in particular, polysaccharide structures contained in cell walls. Se-enriched mycelia of Pleurotus ostreatus were obtained in submerged cultures. The incorporation of selenium from the growth medium to mycelia was observed with the relative distribution between cytosol plus cell membranes fraction (CCM) and cell walls fraction (CW) of about 44 and 56%, respectively.

Transformation of Mucor circinelloides with autoreplicative vectors containing homologous and heterologous ARS elements and the dominant Cbx(r) carboxine-resistance gene.

Mucor circinelloides transformants prototrophic to leucine and resistant to carboxine (Leu(+) Cbx(r)) have been obtained by treatment of protoplasts with plasmid constructs containing homologous leuA gene and adjacent autonomously replicating sequences (ARS) element combined with the Cbx(r)(carboxine-resistance) gene of Ustilago maydis and ARS sequences from this basidiomycete (plasmid pGG37) or from the 2 mu plasmid of Saccharomyces cerevisiae (plasmid pGG43). The presence in the same plasmid molecule of the M. circinelloides leuA gene and adjacent ARS element together with heterologous ARS elements produced an increase in the transformation frequency of about 65-120%.