RESUMEN
Microbial remediation plays a pivotal role in the elimination of petroleum pollutants, making it imperative to investigate the capabilities of microorganisms in degrading petroleum. The present study describes the isolation of a promising strain, Acinetobacter sp. HX09, from petroleum-contaminated water. GC-MS analysis revealed a remarkable removal efficiency for short and medium-chain alkanes, with a rate of approximately 64% after a 7-days incubation at 30 °C. Transcriptome analysis of HX09 exhibited a predominant upregulation in gene expression levels by the induce of crude oil. Notably, genes such as alkane 1-monooxygenase, dehydrogenases and fatty acid metabolic enzymes exhibited fold changes range from 3.16 to 1.3. Based on the alkB gene sequences in HX09, the Phyre2 algorithm generated a three-dimensional structure that exhibited similarity to segments of acyl coenzyme desaturases and acyl lipid desaturases. Furthermore, three biodegradation-related gene clusters were predicted in HX09 based on the reference genome sequence. These findings contribute to our understanding of the hydrocarbon-degrading mechanisms employed by Acinetobacter species and facilitate the development of effective remediation strategies for crude oil- polluted environments.
Asunto(s)
Acinetobacter calcoaceticus , Biodegradación Ambiental , Perfilación de la Expresión Génica , Petróleo , Petróleo/metabolismo , Acinetobacter calcoaceticus/genética , Acinetobacter calcoaceticus/metabolismo , Acinetobacter calcoaceticus/enzimología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Alcanos/metabolismo , Contaminantes Químicos del Agua/metabolismo , FilogeniaRESUMEN
Bacterial degradation of crude oil is a promising strategy for reducing the concentration of hydrocarbons in contaminated environments. In the first part of this study, we report the enrichment of two bacterial consortia from deep sediments of the Gulf of Mexico with crude oil as the sole carbon and energy source. We conducted a comparative analysis of the bacterial community in the original sediment, assessing its diversity, and compared it to the enrichment observed after exposure to crude oil in defined cultures. The consortium exhibiting the highest hydrocarbon degradation was predominantly enriched with Rhodococcus (75%). Bacterial community analysis revealed the presence of other hydrocarbonoclastic members in both consortia. In the second part, we report the isolation of the strain Rhodococcus sp. GOMB7 with crude oil as a unique carbon source under microaerobic conditions and its characterization. This strain demonstrated the ability to degrade long-chain alkanes, including eicosane, tetracosane, and octacosane. We named this new strain Rhodococcus qingshengii GOMB7. Genome analysis revealed the presence of several genes related to aromatic compound degradation, such as benA, benB, benC, catA, catB, and catC; and five alkB genes related to alkane degradation. Although members of the genus Rhodococcus are well known for their great metabolic versatility, including the aerobic degradation of recalcitrant organic compounds such as petroleum hydrocarbons, this is the first report of a novel strain of Rhodococcus capable of degrading long-chain alkanes under microaerobic conditions. The potential of R. qingshengii GOMB7 for applications in bioreactors or controlled systems with low oxygen levels offers an energy-efficient approach for treating crude oil-contaminated water and sediments.
Asunto(s)
Petróleo , Rhodococcus , Petróleo/metabolismo , Golfo de México , Alcanos/metabolismo , Hidrocarburos/metabolismo , Rhodococcus/metabolismo , Biodegradación AmbientalRESUMEN
Since the beginning of oil exploration, whole ecosystems have been affected by accidents and bad practices involving petroleum compounds. In this sense, bioremediation stands out as the cheapest and most eco-friendly alternatives to reverse the damage done in oil-impacted areas. However, more efforts must be made to engineer enzymes that could be used in the bioremediation process. Interestingly, a recent work described that α-amylase, one of the most evolutionary conserved enzymes, was able to promiscuously degrade n-alkanes, a class of molecules abundant in the petroleum admixture. Considering that α-amylase is expressed in almost all known organisms, and employed in numerous biotechnological processes, using it can be a great leap toward more efficient applications of enzyme or microorganism-consortia bioremediation approaches. In this work, we employed a strict computational approach to design new α-amylase mutants with potentially enhanced catalytic efficiency toward n-alkanes. Using in silico techniques, such as molecular docking, molecular dynamics, metadynamics, and residue-residue interaction networks, we generated mutants potentially more efficient for degrading n-alkanes, L183Y, and N314A. Our results indicate that the new mutants have an increased binding rate for tetradecane, the longest n-alkane previously tested, which can reside in the catalytic center for more extended periods. Additionally, molecular dynamics and network analysis showed that the new mutations have no negative impact on protein structure than the WT. Our results aid in solidifying this enzyme as one more tool in the petroleum bioremediation toolbox.
Asunto(s)
Alcanos/metabolismo , Simulación del Acoplamiento Molecular , alfa-Amilasas/metabolismo , Alcanos/química , Bacillus subtilis/enzimología , Biocatálisis , Biodegradación Ambiental , alfa-Amilasas/química , alfa-Amilasas/genéticaRESUMEN
When developing new products to be used in honeybee colonies, further than acute toxicity, it is imperative to perform an assessment of risks, including various sublethal effects. The long-term sublethal effects of xenobiotics on honeybees, more specifically of acaricides used in honeybee hives, have been scarcely studied, particularly so in the case of essential oils and their components. In this work, chronic effects of the ingestion of Eupatorium buniifolium (Asteraceae) essential oil were studied on nurse honeybees using laboratory assays. Survival, food consumption, and the effect on the composition of cuticular hydrocarbons (CHC) were assessed. CHC were chosen due to their key role as pheromones involved in honeybee social recognition. While food consumption and survival were not affected by the consumption of the essential oil, CHC amounts and profiles showed dose-dependent changes. All groups of CHC (linear and branched alkanes, alkenes and alkadienes) were altered when honeybees were fed with the highest essential oil dose tested (6000 ppm). The compounds that significantly varied include n-docosane, n-tricosane, n-tetracosane, n-triacontane, n-tritriacontane, 9-tricosene, 7-pentacosene, 9-pentacosene, 9-heptacosene, tritriacontene, pentacosadiene, hentriacontadiene, tritriacontadiene and all methyl alkanes. All of them but pentacosadiene were up-regulated. On the other hand, CHC profiles were similar in healthy and Nosema-infected honeybees when diets included the essential oil at 300 and 3000 ppm. Our results show that the ingestion of an essential oil can impact CHC and that the effect is dose-dependent. Changes in CHC could affect the signaling process mediated by these pheromonal compounds. To our knowledge this is the first report of changes in honeybee cuticular hydrocarbons as a result of essential oil ingestion.
Asunto(s)
Abejas/efectos de los fármacos , Abejas/metabolismo , Eupatorium/química , Aceites Volátiles/metabolismo , Aceites Volátiles/toxicidad , Alcanos/metabolismo , Alquenos/metabolismo , Animales , Abejas/microbiología , Hidrocarburos/metabolismo , Nosema/patogenicidadRESUMEN
In the last decades, efforts to reduce the use of fossil fuels have increased the search for alternative sustainable sources of renewable energy. In this scenario, hydrocarbons derived from fatty acids are among the compounds that have been drawing attention. The intracellular production of hydrocarbons by bacteria derived from cold environments such as the Antarctic continent is currently poorly investigated, as extremophilic microorganisms provide a great range of metabolic capabilities and may represent a key tool in the production of biofuels. The aim of this study was to explore the ability of bacterial cells derived from extreme environments to produce hydrocarbons with potential for further use as biofuels. Seven bacteria isolated from Antarctic samples were evaluated for hydrocarbon production using GC-MS approaches. Two isolates, identified as Arthrobacter livingstonensis 593 and Pseudoalteromonas arctica 628, were able to produce the hydrocarbon undecane (CH3-(CH2)9-CH3) in concentrations of 1.39 mg L-1 and 1.81 mg L-1, respectively. Results from the present work encourage further research focusing on the optimization of hydrocarbon production by the isolates identified as producers, which may be used in further aircraft biofuel production. This is the first report on the production of the undecane compound by bacteria isolated from waterlogged soil and sponge from Antarctica.
Asunto(s)
Alcanos/metabolismo , Arthrobacter/metabolismo , Biocombustibles , Pseudoalteromonas/metabolismo , Regiones Antárticas , Microbiología del SueloRESUMEN
Metarhizium species are the most abundant fungi that can be isolated from soil, with a well-known biopesticide capacity. Metarhizium recognizes their hosts when the conidium interacts with insects, where the fungi are in contact with the hydrocarbons of the outermost lipid layer cuticle. These cuticular hydrocarbons comprise a mixture of n-alkanes, n-alkenes, and methyl-branched chains. Metarhizium can degrade insect hydrocarbons and use these hydrocarbons for energy production and the biosynthesis of cellular components. The metabolism of nitroalkanes involves nitronate monooxygenase activity. In this work, we isolated a family of six genes with potential nitronate monooxygenase activity from Metarhizium brunneum. The six genes were expressed in Escherichia coli, and the nitronate monooxygenase activity was verified in the recombinant proteins. Additionally, when the conidia of M. brunneum were grown in medium with nitroalkanes, virulence against Plutella xylostella increased. Furthermore, we analyzed the expression of the six Npd genes during the infection to this insect, which showed differential expression of the six Npd genes during infection.
Asunto(s)
Agentes de Control Biológico/metabolismo , Dioxigenasas/metabolismo , Metarhizium/enzimología , Mariposas Nocturnas/microbiología , Alcanos/metabolismo , Animales , ADN de Hongos/genética , Dioxigenasas/genética , Hidrocarburos/metabolismo , Proteínas de Insectos/metabolismo , Metarhizium/genética , Metarhizium/patogenicidad , Control Biológico de Vectores , Virulencia/genéticaRESUMEN
Crude oil and gases in the seabed provide an important energy source for subsurface microorganisms. We investigated the role of archaea in the anaerobic degradation of non-methane alkanes in deep-sea oil seeps from the Gulf of Mexico. We identified microscopically the ethane and short-chain alkane oxidizers "Candidatus Argoarchaeum" and "Candidatus Syntrophoarchaeum" forming consortia with bacteria. Moreover, we found that the sediments contain large numbers of cells from the archaeal clade "Candidatus Methanoliparia," which was previously proposed to perform methanogenic alkane degradation. "Ca. Methanoliparia" occurred abundantly as single cells attached to oil droplets in sediments without apparent bacterial or archaeal partners. Metagenome-assembled genomes of "Ca. Methanoliparia" encode a complete methanogenesis pathway including a canonical methyl-coenzyme M reductase (MCR) but also a highly divergent MCR related to those of alkane-degrading archaea and pathways for the oxidation of long-chain alkyl units. Its metabolic genomic potential and its global detection in hydrocarbon reservoirs suggest that "Ca. Methanoliparia" is an important methanogenic alkane degrader in subsurface environments, producing methane by alkane disproportionation as a single organism.IMPORTANCE Oil-rich sediments from the Gulf of Mexico were found to contain diverse alkane-degrading groups of archaea. The symbiotic, consortium-forming "Candidatus Argoarchaeum" and "Candidatus Syntrophoarchaeum" are likely responsible for the degradation of ethane and short-chain alkanes, with the help of sulfate-reducing bacteria. "Ca. Methanoliparia" occurs as single cells associated with oil droplets. These archaea encode two phylogenetically different methyl-coenzyme M reductases that may allow this organism to thrive as a methanogen on a substrate of long-chain alkanes. Based on a library survey, we show that "Ca. Methanoliparia" is frequently detected in oil reservoirs and may be a key agent in the transformation of long-chain alkanes to methane. Our findings provide evidence for the important and diverse roles of archaea in alkane-rich marine habitats and support the notion of a significant functional versatility of the methyl coenzyme M reductase.
Asunto(s)
Alcanos/metabolismo , Anaerobiosis/fisiología , Euryarchaeota/metabolismo , Hidrocarburos/metabolismo , Metano/metabolismo , Bacterias/metabolismo , Biodegradación Ambiental , Euryarchaeota/clasificación , Euryarchaeota/genética , Ácidos Grasos/metabolismo , Sedimentos Geológicos/microbiología , Golfo de México , Metagenómica , Yacimiento de Petróleo y Gas/microbiología , Oxidación-Reducción , Oxidorreductasas , Filogenia , ARN Ribosómico 16S/genéticaRESUMEN
The aim of the study was the investigation of bacterial diversity from sediments collected at Santos Estuarine System, regarding to their abilities for hexadecane biotransformation. Hexadecane is a medium-chain linear alkane, considered as a model molecule for hydrocarbon biodegradation studies. It is a component from aliphatic fraction of crude petroleum, commonly related to environmental contamination by diesel oil. Santos Basin is an area with historical petroleum contamination. In the present work, sediment samples from this area were inoculated in artificial seawater (ASW), containing hexadecane as carbon source. Six bacterial isolates were selected as resistant to hexadecane. Chromatographic results showed biodegradation indexes above 97%. After 48â¯h of culture, five of them could degrade >80% of the initial hexadecane added. These isolates were characterized by 16S rDNA gene sequencing analysis. The following species were found: Bacillus amyloliquefaciens, Staphylococcus epidermidis, Micrococcus luteus, Nitratireductor aquimarinus, and Bacillus pumilus.
Asunto(s)
Alcanos/metabolismo , Bacterias/aislamiento & purificación , Bacterias/metabolismo , Sedimentos Geológicos/microbiología , Bacterias/genética , Biodegradación Ambiental , ADN Ribosómico , Gasolina , Petróleo/metabolismo , Contaminación por Petróleo , Agua de Mar/microbiología , Contaminantes Químicos del Agua/metabolismoRESUMEN
Hydrocarbons are important environmental pollutants, and the isolation and characterization of new microorganisms with the ability to degrade these compounds are important for effective biodegradation. In this work we isolated and characterized several bacterial isolates from compost, a substrate rich in microbial diversity. The isolates were obtained from selective culture medium containing n-hexadecane, aiming to recover alkane-degraders. Six isolates identified as Gordonia by MALDI-TOF and 16S rRNA sequencing had the ability to degrade n-hexadecane in three days. Two isolates were selected for genomic and functional characterization, Gordonia paraffinivorans (MTZ052) and Gordonia sihwensis (MTZ096). The CG-MS results showed distinct n-hexadecane degradation rates for MTZ052 and MTZ096 (86% and 100% respectively). The genome sequence showed that MTZ052 encodes only one alkane degrading gene cluster, the CYP153 system, while MTZ096 harbors both the Alkane Hydroxylase (AH) and the CYP153 systems. qPCR showed that both gene clusters are induced by the presence of n-hexadecane in the growth medium, suggesting that G. paraffinivorans and G. sihwensis use these systems for degradation. Altogether, our results indicate that these Gordonia isolates have a good potential for biotransformation of hydrocarbons.
Asunto(s)
Actinobacteria , Alcanos/metabolismo , Compostaje , Microbiología del Suelo , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , Actinobacteria/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Genoma BacterianoRESUMEN
Unplanned oil spills during offshore oil production are a serious problem for the industry and the marine environment. Here we assess the biodegradation potential of marine microorganisms from three water depths in the Campos Basin (South Atlantic Ocean): (i) 5â¯m (surface), (ii) â¼80â¯m (chlorophyll maximum layer), and (iii) â¼1200â¯m (near the bottom). After incubating seawater samples with or without crude oil for 52 days, we used metagenomics and classic microbiology techniques to analyze microbial abundance and diversity, and measured physical-chemical parameters to better understand biodegradation processes. We observed increased microbial abundance and concomitant decreases in dissolved oxygen and hydrocarbon concentrations, indicating oil biodegradation in the three water depths treatments within approximately 27 days. An increase in metagenomic sequences of oil-degrading archaea, fungi, and bacteria (Alcanivorax, Alteromonas, Colwellia, Marinobacter, and Pseudomonas) accompanied by a significant increase in metagenomic sequences involved in the degradation of aromatic compounds indicate that crude oil promotes the growth of microorganisms with oil degradation potential. The abundance of genes involved in biodegrading benzene, toluene, ethylbenzene, xylene, alkanes, and poly-aromatic hydrocarbons peaked approximately 3 days after oil addition. All 12 novel metagenome-assembled genomes contained genes involved in hydrocarbon degradation, indicating the oil-degrading potential of planktonic microbes in the Campos Basin.
Asunto(s)
Biodegradación Ambiental , Monitoreo del Ambiente , Metagenómica , Contaminación por Petróleo/análisis , Petróleo/metabolismo , Microbiología del Agua , Alcanos/metabolismo , Océano Atlántico , Bacterias/metabolismo , Hidrocarburos/análisis , Hidrocarburos/metabolismo , Metagenoma , Agua de Mar/químicaRESUMEN
Cuticular hydrocarbons (CHCs), the dominant fraction of the insects' epicuticle and the primary barrier to desiccation, form the basis for a wide range of chemical signaling systems. In eusocial insects, CHCs are key mediators of nestmate recognition, and colony identity appears to be maintained through a uniform CHC profile. In the unicolonial Argentine ant Linepithema humile, an unparalleled invasive expansion has led to vast supercolonies whose nestmates can still recognize each other across thousands of miles. CHC profiles are expected to display considerable variation as they adapt to fundamentally differing environmental conditions across the Argentine ant's expanded range, yet this variation would largely conflict with the vastly extended nestmate recognition based on CHC uniformity. To shed light on these seemingly contradictory selective pressures, we attempt to decipher which CHC classes enable adaptation to such a wide array of environmental conditions and contrast them with the overall CHC profile uniformity postulated to maintain nestmate recognition. n-Alkanes and n-alkenes showed the largest adaptability to environmental conditions most closely associated with desiccation, pointing at their function for water-proofing. Trimethyl alkanes, on the other hand, were reduced in environments associated with higher desiccation stress. However, CHC patterns correlated with environmental conditions were largely overriden when taking overall CHC variation across the expanded range of L. humile into account, resulting in conserved colony-specific CHC signatures. This delivers intriguing insights into the hierarchy of CHC functionality integrating both adaptation to a wide array of different climatic conditions and the maintenance of a universally accepted chemical profile.
Asunto(s)
Adaptación Fisiológica , Hormigas/fisiología , Hidrocarburos/metabolismo , Alcanos/análisis , Alcanos/aislamiento & purificación , Alcanos/metabolismo , Animales , Argentina , Biodiversidad , California , Clima , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos/análisis , Hidrocarburos/aislamiento & purificación , Especies Introducidas , Extracción Líquido-LíquidoRESUMEN
Abstract The effect of the intracellular microenvironment in the presence of an oxygen vector during expression of a fusion protein in Escherichia coli was studied. Three organic solutions at different concentration were chosen as oxygen vectors for fumarase expression. The addition of n-dodecane did not induce a significant change in the expression of fumarase, while the activity of fumarase increased significantly to 124% at 2.5% n-dodecane added after 9 h induction. The concentration of ATP increased sharply during the first 6 h of induction, to a value 7600% higher than that in the absence of an oxygen-vector. NAD/NADH and NADP/NADPH ratios were positively correlated with fumarase activity. n-Dodecane can be used to increase the concentration of ATP and change the energy metabolic pathway, providing sufficient energy for fumarase folding.
Asunto(s)
Oxígeno/metabolismo , Expresión Génica , Alcanos/metabolismo , Escherichia coli/genética , Fumarato Hidratasa/metabolismo , Oxígeno/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/química , Pliegue de Proteína , Alcanos/química , Escherichia coli/metabolismo , Fumarato Hidratasa/genética , Fumarato Hidratasa/química , NADP/metabolismo , NADP/químicaRESUMEN
The entomopathogenic fungus Beauveria bassiana is able to grow on insect cuticle hydrocarbons, inducing alkane assimilation pathways and concomitantly increasing virulence against insect hosts. In this study, we describe some physiological and molecular processes implicated in growth, nutritional stress response, and cellular alterations found in alkane-grown fungi. The fungal cytology was investigated using light and transmission electron microscopy while the surface topography was examined using atomic force microscopy. Additionally, the expression pattern of several genes associated with oxidative stress, peroxisome biogenesis, and hydrophobicity were analysed by qPCR. We found a novel type of growth in alkane-cultured B. bassiana similar to mycelial pellets described in other alkane-free fungi, which were able to produce viable conidia and to be pathogenic against larvae of the beetles Tenebrio molitor and Tribolium castaneum. Mycelial pellets were formed by hyphae cumulates with high peroxidase activity, exhibiting peroxisome proliferation and an apparent surface thickening. Alkane-grown conidia appeared to be more hydrophobic and cell surfaces displayed different topography than glucose-grown cells. We also found a significant induction in several genes encoding for peroxins, catalases, superoxide dismutases, and hydrophobins. These results show that both morphological and metabolic changes are triggered in mycelial pellets derived from alkane-grown B. bassiana.
Asunto(s)
Alcanos/metabolismo , Beauveria/crecimiento & desarrollo , Beauveria/patogenicidad , Entomophthorales/crecimiento & desarrollo , Entomophthorales/patogenicidad , Estrés Oxidativo , Animales , Beauveria/metabolismo , Membrana Celular/ultraestructura , Proliferación Celular , Entomophthorales/metabolismo , Hifa/metabolismo , Insectos/microbiología , Larva/microbiología , Peroxisomas/fisiología , Esporas Fúngicas/metabolismo , VirulenciaRESUMEN
The effect of the intracellular microenvironment in the presence of an oxygen vector during expression of a fusion protein in Escherichia coli was studied. Three organic solutions at different concentration were chosen as oxygen vectors for fumarase expression. The addition of n-dodecane did not induce a significant change in the expression of fumarase, while the activity of fumarase increased significantly to 124% at 2.5% n-dodecane added after 9h induction. The concentration of ATP increased sharply during the first 6h of induction, to a value 7600% higher than that in the absence of an oxygen-vector. NAD/NADH and NADP/NADPH ratios were positively correlated with fumarase activity. n-Dodecane can be used to increase the concentration of ATP and change the energy metabolic pathway, providing sufficient energy for fumarase folding.
Asunto(s)
Alcanos/metabolismo , Escherichia coli/genética , Fumarato Hidratasa/metabolismo , Expresión Génica , Oxígeno/metabolismo , Alcanos/química , Escherichia coli/metabolismo , Fumarato Hidratasa/química , Fumarato Hidratasa/genética , NADP/química , NADP/metabolismo , Oxígeno/química , Pliegue de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
Drill cuttings leave behind thousands of tons of residues without adequate treatment, generating a large environmental liability. Therefore knowledge about the microbial community of drilling residue may be useful for developing bioremediation strategies. In this work, samples of drilling residue were enriched in different culture media in the presence of petroleum, aiming to select potentially oil-degrading bacteria and biosurfactant producers. Total DNA was extracted directly from the drill cutting samples and from two enriched consortia and sequenced using the Ion Torrent platform. Taxonomic analysis revealed the predominance of Proteobacteria in the metagenome from the drill cuttings, while Firmicutes was enriched in consortia samples. Functional analysis using the Biosurfactants and Biodegradation Database (BioSurfDB) revealed a similar pattern among the three samples regarding hydrocarbon degradation and biosurfactants production pathways. However, some statistical differences were observed between samples. Namely, the pathways related to the degradation of fatty acids, chloroalkanes, and chloroalkanes were enriched in consortia samples. The degradation colorimetric assay using dichlorophenolindophenol as an indicator was positive for several hydrocarbon substrates. The consortia were also able to produce biosurfactants, with biosynthesis of iturin, lichnysin, and surfactin among the more abundant pathways. A microcosms assay followed by gas chromatography analysis showed the efficacy of the consortia in degrading alkanes, as we observed a reduction of around 66% and 30% for each consortium in total alkanes. These data suggest the potential use of these consortia in the bioremediation of drilling residue based on autochthonous bioaugmentation.
Asunto(s)
Bacterias/metabolismo , Biodegradación Ambiental , Contaminantes Ambientales/metabolismo , Genoma Bacteriano , Metagenoma , Consorcios Microbianos , Petróleo/metabolismo , Alcanos/metabolismo , Hidrocarburos/metabolismoRESUMEN
Diesel fuel is one of the most important sources of hydrocarbon contamination worldwide. Its composition consists of a complex mixture of n-alkanes, branched alkanes and aromatic compounds. Hydrocarbon degradation in Pseudomonas species has been mostly studied under aerobic conditions; however, a dynamic spectrum of oxygen availability can be found in the environment. Pseudomonas extremaustralis, an Antarctic bacterium isolated from a pristine environment, is able to degrade diesel fuel and presents a wide microaerophilic metabolism. In this work RNA-deep sequence experiments were analyzed comparing the expression profile in aerobic and microaerophilic cultures. Interestingly, genes involved in alkane degradation, including alkB, were over-expressed in micro-aerobiosis in absence of hydrocarbon compounds. In minimal media supplemented with diesel fuel, n-alkanes degradation (C13-C19) after 7 days was observed under low oxygen conditions but not in aerobiosis. In-silico analysis of the alkB promoter zone showed a putative binding sequence for the anaerobic global regulator, Anr. Our results indicate that some diesel fuel components can be utilized as sole carbon source under microaerophilic conditions for cell maintenance or slow growth in a Pseudomonas species and this metabolism could represent an adaptive advantage in polluted environments.
Asunto(s)
Alcanos/metabolismo , Gasolina , Pseudomonas/metabolismo , Aerobiosis , Biodegradación Ambiental , Citocromo P-450 CYP4A/genética , Citocromo P-450 CYP4A/metabolismo , Pseudomonas/enzimología , Pseudomonas/genética , TranscriptomaRESUMEN
In April of 2010, the Macondo well blowout in the northern Gulf of Mexico resulted in an unprecedented release of oil into the water column at a depth of approximately 1500 m. A time series of surface and subsurface sediment samples were collected to the northwest of the well from 2010 to 2013 for molecular biomarker and bulk carbon isotopic analyses. While no clear trend was observed in subsurface sediments, surface sediments (0-3 cm) showed a clear pattern with total concentrations of n-alkanes, unresolved complex mixture (UCM), and petroleum biomarkers (terpanes, hopanes, steranes) increasing from May to September 2010, peaking in late November 2010, and strongly decreasing in the subsequent years. The peak in hydrocarbon concentrations were corroborated by higher organic carbon contents, more depleted Δ14C values and biomarker ratios similar to those of the initial MC252 crude oil reported in the literature. These results indicate that at least part of oil discharged from the accident sedimented to the seafloor in subsequent months, resulting in an apparent accumulation of hydrocarbons on the seabed by the end of 2010. Sediment resuspension and transport or biodegradation may account for the decrease in sedimented oil quantities in the years following the Macondo well spill.
Asunto(s)
Monitoreo del Ambiente , Hidrocarburos/análisis , Contaminación por Petróleo/análisis , Contaminantes Químicos del Agua/análisis , Alcanos/metabolismo , Biodegradación Ambiental , Sedimentos Geológicos/análisis , Sedimentos Geológicos/química , Golfo de México , Petróleo/análisisRESUMEN
The effects of electric current on membranes associated with metabolism modifications in Aspergillus brasiliensis (niger) ATCC 9642 were studied. A 450-mL electrochemical cell with titanium ruthenium-oxide coated electrodes and packed with 15g of perlite, as inert support, was inoculated with A. brasiliensis spores and incubated in a solid inert-substrate culture (12 d; 30°C). Then, 4.5days after starting the culture, a current of 0.42mAcm-2 was applied for 24h. The application of low-intensity electric current increased the molecular oxygen consumption rate in the mitochondrial respiratory chain, resulting in high concentrations of reactive oxygen species, promoting high lipoperoxidation levels, according to measured malondialdehyde, and consequent alterations in membrane permeability explained the high n-hexadecane (HXD) degradation rates observed here (4.7-fold higher than cultures without current). Finally, cell differentiation and spore production were strongly stimulated. The study contributes to the understanding of the effect of current on the cell membrane and its association with HXD metabolism.
Asunto(s)
Aspergillus niger/citología , Aspergillus niger/metabolismo , Membrana Celular/metabolismo , Conductividad Eléctrica , Alcanos/metabolismo , Biomasa , Reactores Biológicos/microbiología , Dióxido de Carbono/metabolismo , Electroquímica , Oxígeno/metabolismo , Esporas Fúngicas/metabolismoRESUMEN
The combination of biological and electrochemical techniques enhances the bioremediation efficiency of treating oil-contaminated water. In this study a non-growing fungal whole cell biocatalyst (BC; Aspergillus brasiliensis attached to perlite) pretreated with an electric field (EF), was used to degrade a hydrocarbon blend (hexadecane-phenanthrene-pyrene; 100:1:1w/w) in an airlift bioreactor (ALB). During hydrocarbon degradation, all mass transfer resistances (internal and external) and sorption capacity were experimentally quantified. Internal mass transfer resistances were evaluated through BC effectiveness factor analysis as a function of the Thiele modulus (using first order reaction kinetics, assuming a spherical BC, five particle diameters). External (interfacial) mass transfer resistances were evaluated by kLa determination. EF pretreatment during BC production promoted surface changes in BC and production of an emulsifier protein in the ALB. The BC surface modifications enhanced the affinity for hydrocarbons, improving hydrocarbon uptake by direct contact. The resulting emulsion was associated with decreased internal and external mass transfer resistances. EF pretreatment effects can be summarized as: a combined uptake mechanism (direct contact dominant followed by emulsified form dominant) diminishing mass transfer limitations, resulting in a non-specific hydrocarbon degradation in blend. The pretreated BC is a good applicant for oil-contaminated water remediation.
Asunto(s)
Alcanos/metabolismo , Aspergillus/metabolismo , Biocatálisis , Reactores Biológicos , Restauración y Remediación Ambiental/instrumentación , Contaminación por Petróleo , Fenantrenos/metabolismo , Pirenos/metabolismo , Contaminantes Químicos del Agua/metabolismo , Biodegradación Ambiental , Electricidad , Emulsiones , Proteínas Fúngicas/biosíntesis , Cinética , TermodinámicaRESUMEN
The analysis of catabolic capacities of microorganisms is currently often achieved by cultivation approaches and by the analysis of genomic or metagenomic datasets. Recently, a microarray system designed from curated key aromatic catabolic gene families and key alkane degradation genes was designed. The collection of genes in the microarray can be exploited to indicate whether a given microbe or microbial community is likely to be functionally connected with certain degradative phenotypes, without previous knowledge of genome data. Herein, this microarray was applied to capture new insights into the catabolic capacities of copper-resistant actinomycete Amycolatopsis tucumanensis DSM 45259. The array data support the presumptive ability of the DSM 45259 strain to utilize single alkanes (n-decane and n-tetradecane) and aromatics such as benzoate, phthalate and phenol as sole carbon sources, which was experimentally validated by cultivation and mass spectrometry. Interestingly, while in strain DSM 45259 alkB gene encoding an alkane hydroxylase is most likely highly similar to that found in other actinomycetes, the genes encoding benzoate 1,2-dioxygenase, phthalate 4,5-dioxygenase and phenol hydroxylase were homologous to proteobacterial genes. This suggests that strain DSM 45259 contains catabolic genes distantly related to those found in other actinomycetes. Together, this study not only provided new insight into the catabolic abilities of strain DSM 45259, but also suggests that this strain contains genes uncommon within actinomycetes.