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1.
Nat Commun ; 12(1): 5032, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413314

RESUMO

Methane, along with other short-chain alkanes from some Archean metasedimentary rocks, has unique isotopic signatures that possibly reflect the generation of atmospheric greenhouse gas on early Earth. We find that alkane gases from the Kidd Creek mines in the Canadian Shield are microbial products in a Neoarchean ecosystem. The widely varied hydrogen and relatively uniform carbon isotopic compositions in the alkanes infer that the alkanes result from the biodegradation of sediment organic matter with serpentinization-derived hydrogen gas. This proposed process is supported by published geochemical data on the Kidd Creek gas, including the distribution of alkane abundances, stable isotope variations in alkanes, and CH2D2 signatures in methane. The recognition of Archean microbial methane in this work reveals a biochemical process of greenhouse gas generation before the Great Oxidation Event and improves the understanding of the carbon and hydrogen geochemical cycles.


Assuntos
Bactérias/metabolismo , Planeta Terra , Gases/química , Sedimentos Geológicos/química , Hidrogênio/química , Hidrogênio/metabolismo , Metano/metabolismo , Fenômenos Microbiológicos , Alcanos/química , Alcanos/metabolismo , Biodegradação Ambiental , Canadá , Isótopos de Carbono/química , Ecossistema , Metano/química , Oxirredução
2.
Sci Rep ; 11(1): 12045, 2021 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103559

RESUMO

Acyl-ACP reductase (AAR) is one of the two key cyanobacterial enzymes along with aldehyde deformylating oxygenase (ADO) involved in the synthesis of long-chain alkanes, a drop-in biofuel. The enzyme is prone to aggregation when expressed in Escherichia coli, leading to varying alkane levels. The present work attempts to investigate the crucial structural aspects of AAR protein associated with its stability and folding. Characterization by dynamic light scattering experiment and intact mass spectrometry revealed that recombinantly expressed AAR in E. coli existed in multiple-sized protein particles due to diverse lipidation. Interestingly, while thermal- and urea-based denaturation of AAR showed 2-state unfolding transition in circular dichroism and intrinsic fluorescent spectroscopy, the unfolding process of AAR was a 3-state pathway in GdnHCl solution suggesting that the protein milieu plays a significant role in dictating its folding. Apparent standard free energy [Formula: see text] of ~ 4.5 kcal/mol for the steady-state unfolding of AAR indicated borderline stability of the protein. Based on these evidences, we propose that the marginal stability of AAR are plausible contributing reasons for aggregation propensity and hence the low catalytic activity of the enzyme when expressed in E. coli for biofuel production. Our results show a path for building superior biocatalyst for higher biofuel production.


Assuntos
Enoil-(Proteína de Transporte de Acila) Redutase (NADPH, B-Específica)/metabolismo , Escherichia coli/enzimologia , Hidrocarbonetos/química , Alcanos/metabolismo , Proteínas de Bactérias/metabolismo , Biocombustíveis , Biofísica , Biotecnologia , Cromatografia , Cromatografia Líquida , Dicroísmo Circular , Luz , Espectrometria de Massas , Simulação de Dinâmica Molecular , Oxigenases/química , Desnaturação Proteica , Dobramento de Proteína , Espalhamento de Radiação , Espectrometria de Fluorescência , Eletricidade Estática , Synechococcus/metabolismo , Temperatura , Ureia/química
3.
J Bacteriol ; 203(17): e0011721, 2021 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-34124941

RESUMO

Archaeal methanogens, methanotrophs, and alkanotrophs have a high demand for iron (Fe) and sulfur (S); however, little is known of how they acquire, traffic, deploy, and store these elements. Here, we examined the distribution of homologs of proteins mediating key steps in Fe/S metabolism in model microorganisms, including iron(II) sensing/uptake (FeoAB), sulfide extraction from cysteine (SufS), and the biosynthesis of iron-sulfur [Fe-S] clusters (SufBCDE), siroheme (Pch2 dehydrogenase), protoheme (AhbABCD), cytochrome c (Cyt c) (CcmCF), and iron storage/detoxification (Bfr, FtrA, and IssA), among 326 publicly available, complete or metagenome-assembled genomes of archaeal methanogens/methanotrophs/alkanotrophs. The results indicate several prevalent but nonuniversal features, including FeoB, SufBC, and the biosynthetic apparatus for the basic tetrapyrrole scaffold, as well as its siroheme (and F430) derivatives. However, several early-diverging genomes lacked SufS and pathways to synthesize and deploy heme. Genomes encoding complete versus incomplete heme biosynthetic pathways exhibited equivalent prevalences of [Fe-S] cluster binding proteins, suggesting an expansion of catalytic capabilities rather than substitution of heme for [Fe-S] in the former group. Several strains with heme binding proteins lacked heme biosynthesis capabilities, while other strains with siroheme biosynthesis capability lacked homologs of known siroheme binding proteins, indicating heme auxotrophy and unknown siroheme biochemistry, respectively. While ferritin proteins involved in ferric oxide storage were widespread, those involved in storing Fe as thioferrate were unevenly distributed. Collectively, the results suggest that differences in the mechanisms of Fe and S acquisition, deployment, and storage have accompanied the diversification of methanogens/methanotrophs/alkanotrophs, possibly in response to differential availability of these elements as these organisms evolved. IMPORTANCE Archaeal methanogens, methanotrophs, and alkanotrophs, argued to be among the most ancient forms of life, have a high demand for iron (Fe) and sulfur (S) for cofactor biosynthesis, among other uses. Here, using comparative bioinformatic approaches applied to 326 genomes, we show that major differences in Fe/S acquisition, trafficking, deployment, and storage exist in this group. Variation in these characters was generally congruent with the phylogenetic placement of these genomes, indicating that variation in Fe/S usage and deployment has contributed to the diversification and ecology of these organisms. However, incongruency was observed among the distribution of cofactor biosynthesis pathways and known protein destinations for those cofactors, suggesting auxotrophy or yet-to-be-discovered pathways for cofactor biosynthesis.


Assuntos
Alcanos/metabolismo , Archaea/classificação , Archaea/metabolismo , Coenzimas/metabolismo , Ferro/metabolismo , Metano/metabolismo , Enxofre/metabolismo , Archaea/genética , Archaea/isolamento & purificação , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Processos Autotróficos , Vias Biossintéticas , Cisteína/metabolismo , Compostos Férricos/metabolismo , Heme/análogos & derivados , Heme/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Filogenia
4.
mBio ; 12(3)2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-34006650

RESUMO

The recent leveraging of genome-resolved metagenomics has generated an enormous number of genomes from novel uncultured microbial lineages yet left many clades undescribed. Here, we present a global analysis of genomes belonging to Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, and chloromethanes as the substrates. Methylotrophy in Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e., the utilization of diverse sets of genes, pathways, and combinations to achieve a specific metabolic goal. The genomes also encoded multiple alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, ß- and γ-carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified, although absence of key genes and failure to identify a photosynthetic reaction center preclude proposing phototrophic capacities. Analysis of 16S rRNA databases showed the preferences of Binatota to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges, supporting their potential role in mitigating methanol and methane emissions, breakdown of alkanes, and their association with sponges. Our results expand the lists of methylotrophic, aerobic alkane-degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion.IMPORTANCE A wide range of microbial lineages remain uncultured, yet little is known regarding their metabolic capacities, physiological preferences, and ecological roles in various ecosystems. We conducted a thorough comparative genomic analysis of 108 genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. We present evidence that members of the order Binatota specialize in methylotrophy and identify an extensive repertoire of genes and pathways mediating the oxidation of multiple one-carbon (C1) compounds in Binatota genomes. The occurrence of multiple alkane hydroxylases and monooxygenases in these genomes was also identified, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids production. We also report on the presence of incomplete chlorophyll biosynthetic pathways in all genomes and propose several evolutionary-grounded scenarios that could explain such a pattern. Assessment of the ecological distribution patterns of the Binatota indicates preference of its members to terrestrial and freshwater ecosystems characterized by high methane and methanol emissions, as well as multiple hydrocarbon-rich habitats and marine sponges.


Assuntos
Alcanos/metabolismo , Bactérias/genética , Bactérias/metabolismo , Genoma Bacteriano , Genômica/métodos , Pigmentos Biológicos/biossíntese , Bactérias/classificação , Ecossistema , Filogenia , Pigmentos Biológicos/genética , RNA Ribossômico 16S/genética
5.
Artigo em Inglês | MEDLINE | ID: mdl-34019473

RESUMO

This work assessed the catabolic versatility of functional genes in hydrocarbon-utilizing bacteria obtained from the rhizosphere of plants harvested in aged polluted soil sites in Ogoni and their attenuation efficacy in a bioremediation study. Rhizosphere soil was enumerated for its hydrocarbon-utilizing bacteria. The bacteria were in-vitro screened and selected through the quantification of their total protein and specific intermediate pathway enzyme (catechol 2,3-dioxygenase) activity in the metabolism of hydrocarbon. Thereafter, agarose gel electrophoresis technique was deployed to profile the genome of the selected strains for catechol 2,3-dioxygenase (C23O), 1,2-alkane monooxygenase (alkB), and naphthalene dioxygenase (nahR). Four rhizobacterial isolates namely Pseudomonas fluorescens (A3), Achromobacter agilis (A4), Bacillus thuringiensis (D2), and Staphylococcus lentus (L1) were selected based on the presence of C23O, alkB, and nahR genes. The gel electrophoresis results showed an approximate molecular weight of 200 bp for alkB, 300 bp for C23O, and 400 bp for nahR. The gas chromatogram for residual total petroleum hydrocarbon (TPH) revealed mineralization of fractions C8-C17, phytane, C18-C30. TPH for in-vitro bioremediation of crude oil-polluted soil was observed to have an optimal reduction/loss of 97% within the 56th day of the investigation. This study has further revealed that the microbiome of plants pre-exposed to crude oil pollution could serve as a reservoir for mining group of bacterial with broad catabolic potentials for eco-recovery and waste treatment purposes.


Assuntos
Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Petróleo/análise , Alcanos/metabolismo , Bactérias/genética , Dioxigenases/genética , Dioxigenases/metabolismo , Genes Bacterianos , Complexos Multienzimáticos , Poluição por Petróleo/análise , Microbiologia do Solo
6.
Science ; 372(6538)2021 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-33833098

RESUMO

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.


Assuntos
Carboxiliases/química , Carboxiliases/metabolismo , Chlorella/enzimologia , Ácidos Graxos/metabolismo , Proteínas de Algas/química , Proteínas de Algas/metabolismo , Alcanos/metabolismo , Substituição de Aminoácidos , Aminoácidos/metabolismo , Bicarbonatos/metabolismo , Biocatálise , Dióxido de Carbono/metabolismo , Domínio Catalítico , Cristalografia por Raios X , Descarboxilação , Transporte de Elétrons , Flavina-Adenina Dinucleotídeo/química , Ligação de Hidrogênio , Luz , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Oxirredução , Fótons , Conformação Proteica , Temperatura
7.
Mol Biotechnol ; 63(6): 544-555, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33786739

RESUMO

Candida tropicalis can metabolize alkanes or fatty acids to produce long-chain dicarboxylic acids (DCAs). Fatty acid transporters located on the cell or peroxisome membrane may play an important role in this process. Using amino acid sequence homologous alignment, two putative proteins, CtFat1p and CtPxa1p, located on the cell and peroxisome membrane were found, respectively. Moreover, single- and double-knockout homologous recombination technology was used to study ctfat1p and ctpxa1p gene effects on DCA synthesis. In comparison to the wild-type strain, long-chain DCA yield decreased by 65.14%, 88.38% and 56.19% after single and double-copy knockout of ctfat1p genes and double-copy knockout of ctpxa1p genes, respectively, indicating that the knockout of ctfat1p and ctpxa1p genes had a significant effect on the conversion of oils and fats into long-chain DCAs by C. tropicalis. However, the yield of long-chain DCAs increased by 21.90% after single-knockout of the ctpxa1p gene, indicating that the single-knockout of the ctpxa1p gene may reduce fatty acid transport to peroxisome for further oxidation. Moreover, to improve the intracellular transport rate of fatty acids, ctfat1p copy number increased, increasing DCA yield by 30.10%. These results may provide useful information for enhancing the production of long-chain DCAs by C. tropicalis.


Assuntos
Alcanos/química , Candida tropicalis/química , Ácidos Graxos/química , Engenharia de Proteínas , Alcanos/metabolismo , Sequência de Aminoácidos/genética , Candida tropicalis/enzimologia , Candida tropicalis/metabolismo , Proteínas de Transporte de Ácido Graxo/metabolismo , Ácidos Graxos/metabolismo , Fermentação , Redes e Vias Metabólicas/genética , Oxirredução , Peroxissomos/enzimologia , Peroxissomos/genética , Engenharia de Proteínas/métodos , Alinhamento de Sequência
8.
J Ind Microbiol Biotechnol ; 48(1-2)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33713132

RESUMO

Owing to their high energy density and composition, fatty acid-derived chemicals possess a wide range of applications such as biofuels, biomaterials, and other biochemical, and as a consequence, the global annual demand for products has surpassed 2 million tons. With the exhausting petroleum reservoirs and emerging environmental concerns on using petroleum feedstock, it has become indispensable to shift to a renewable-based industry. With the advancement in the field of synthetic biology and metabolic engineering, the use of microbes as factories for the production of fatty acid-derived chemicals is becoming a promising alternative approach for the production of these derivatives. Numerous metabolic approaches have been developed for conditioning the microbes to improve existing or develop new methodologies capable of efficient oleochemical production. However, there still exist several limitations that need to be addressed for the commercial viability of the microbial cell factory production. Though substantial advancement has been made toward successfully producing these fatty acids derived chemicals, a considerable amount of work needs to be done for improving the titers. In the present review, we aim to address the roadblocks impeding the heterologous production, the engineering pathway strategies implemented across the range of microbes in a detailed manner, and the commercial readiness of these molecules of immense application.


Assuntos
Alcanos/metabolismo , Álcoois Graxos/metabolismo , Animais , Biocombustíveis , Engenharia Metabólica/métodos , Biologia Sintética
9.
J Chem Ecol ; 47(4-5): 420-432, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33682070

RESUMO

Queen pheromones evolved independently in multiple eusocial insect lineages, in which they mediate reproductive conflict by inhibiting worker ovarian development. Although fundamentally important for reproductive division of labor - the hallmark of eusociality - their evolutionary origins are enigmatic. Here, we analyze cuticular and Dufour's gland chemistries across alternative social and reproductive phenotypes in Megalopta genalis bees (tribe Augochlorini, family Halictidae) that facultatively express simple eusociality. Reproductive bees have distinct overall glandular and cuticular chemical phenotypes compared with non-reproductive workers. On the cuticle, a likely site of signal transmission, reproductives are enriched for certain alkenes, most linear alkanes, and are heavily enriched for all methyl-branched alkanes. Chemicals belonging to these compound classes are known to function as fertility signals in other eusocial insect taxa. Some macrocyclic lactones, compounds that serve as queen pheromones in the other eusocial halictid tribe (Halictini), are also enriched among reproductives relative to workers. The intra-population facultative eusociality of M. genalis permits direct comparisons between individuals expressing alternative reproductive phenotypes - females that reproduce alone (solitary reproductives) and social queens - to highlight traits in the latter that may be important mediators of eusociality. Compared with solitary reproductives, the cuticular chemistries of queens are more strongly differentiated from those of workers, and furthermore are especially enriched for methyl-branched alkanes. Determining the pheromonal function(s) and information content of the candidate signaling compounds we identify will help illuminate the early evolutionary history of queen pheromones, chemical signals central to the organization of insect eusocial behavior.


Assuntos
Misturas Complexas/química , Feromônios/química , Feromônios/metabolismo , Alcanos/química , Alcanos/metabolismo , Alcenos/química , Alcenos/metabolismo , Comunicação Animal , Animais , Abelhas , Comportamento Animal , Evolução Biológica , Feminino , Fertilidade , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Reprodução
10.
Nat Microbiol ; 6(4): 489-498, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33526885

RESUMO

Seeps, spills and other oil pollution introduce hydrocarbons into the ocean. Marine cyanobacteria also produce hydrocarbons from fatty acids, but little is known about the size and turnover of this cyanobacterial hydrocarbon cycle. We report that cyanobacteria in an oligotrophic gyre mainly produce n-pentadecane and that microbial hydrocarbon production exhibits stratification and diel cycling in the sunlit surface ocean. Using chemical and isotopic tracing we find that pentadecane production mainly occurs in the lower euphotic zone. Using a multifaceted approach, we estimate that the global flux of cyanobacteria-produced pentadecane exceeds total oil input in the ocean by 100- to 500-fold. We show that rapid pentadecane consumption sustains a population of pentadecane-degrading bacteria, and possibly archaea. Our findings characterize a microbial hydrocarbon cycle in the open ocean that dwarfs oil input. We hypothesize that cyanobacterial hydrocarbon production selectively primes the ocean's microbiome with long-chain alkanes whereas degradation of other petroleum hydrocarbons is controlled by factors including proximity to petroleum seepage.


Assuntos
Hidrocarbonetos/metabolismo , Oceanos e Mares , Água do Mar/microbiologia , Alcanos/análise , Alcanos/metabolismo , Biodegradação Ambiental , Cianobactérias/metabolismo , Cianobactérias/fisiologia , Hidrocarbonetos/análise , Microbiota , Petróleo/metabolismo , Poluição por Petróleo , Água do Mar/química
11.
Appl Environ Microbiol ; 87(9)2021 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-33608298

RESUMO

Biosurfactant production is a common trait in leaf surface-colonizing bacteria that has been associated with increased survival and movement on leaves. At the same time, the ability to degrade aliphatics is common in biosurfactant-producing leaf colonizers. Pseudomonads are common leaf colonizers and have been recognized for their ability to produce biosurfactants and degrade aliphatic compounds. In this study, we investigated the role of biosurfactants in four non-plant-pathogenic Pseudomonas strains by performing a series of experiments to characterize their surfactant properties and their role during leaf colonization and diesel degradation. The biosurfactants produced were identified using mass spectrometry. Two strains produced viscosin-like biosurfactants, and the other two produced massetolide A-like biosurfactants, which aligned with the phylogenetic relatedness between the strains. To further investigate the role of surfactant production, random Tn5 transposon mutagenesis was performed to generate knockout mutants. The knockout mutants were compared to their respective wild types with regard to their ability to colonize gnotobiotic Arabidopsis thaliana and to degrade diesel or dodecane. It was not possible to detect negative effects during plant colonization in direct competition or individual colonization experiments. When grown on diesel, knockout mutants grew significantly slower than their respective wild types. When grown on dodecane, knockout mutants were less impacted than during growth on diesel. By adding isolated wild-type biosurfactants, it was possible to complement the growth of the knockout mutants.IMPORTANCE Many leaf-colonizing bacteria produce surfactants and are able to degrade aliphatic compounds; however, whether surfactant production provides a competitive advantage during leaf colonization is unclear. Furthermore, it is unclear if leaf colonizers take advantage of the aliphatic compounds that constitute the leaf cuticle and cuticular waxes. Here, we tested the effect of surfactant production on leaf colonization, and we demonstrate that the lack of surfactant production decreases the ability to degrade aliphatic compounds. This indicates that leaf surface-dwelling, surfactant-producing bacteria contribute to degradation of environmental hydrocarbons and may be able to utilize leaf surface waxes. This has implications for plant-microbe interactions and future studies.


Assuntos
Arabidopsis/microbiologia , Gasolina , Folhas de Planta/microbiologia , Pseudomonas/metabolismo , Tensoativos/metabolismo , Alcanos/metabolismo , Biodegradação Ambiental , Mutagênese , Filogenia , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , RNA Ribossômico 16S , Tensoativos/química
12.
Mol Phylogenet Evol ; 159: 107101, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33592235

RESUMO

ECERIFERUM1 (CER1) and ECERIFERUM3 (CER3) are key genes in synthesis of alkanes, a major component of cuticular waxes in land plants. The genes share extensive similarity, including the N-terminal (ERG3/FAH) and C-terminal (WAX2) domains. This study, traces the origin, evolutionary history, phylogenetic relationships and variation in copy number of the two genes within and beyond the Viridiplantae (green plants). Protein homologs of both CER1 and CER3 were identified across most Embryophyta (land plants), a single homolog (CER1/3) in charophytes and prasinophytes, and none in the other green, red or brown algae. Ancestral state reconstructions in 100 sequenced Archaeplastida using presence/absence of CER1/3 family genes revealed that the CER1/3 gene probably originated in the common ancestor of Viridiplantae. Phylogenetic analysis of CER1 and CER3 protein sequences from 146 plant species strongly suggests that the two genes originated by duplication of CER1/3 in the ancestral embryophyte. The evolution of CER1 and CER3 genes involved differential divergence of the two domains. Outside Embryophyta, CER1/3 similar sequences identified in diatoms and a cryptophyte, were the closest relatives of the CER1/3 family proteins. Proteins harbouring WAX2-wxAR (WAX2 associated region) similar regions were identified in proteins of bacteria, Archaea, cryptophytes, dinoflagellates and Stramenopiles. The independent existence of both ERG3/FAH and WAX2-wxAR domains in diverse lineages strongly points to the origin of CER1/3 gene in green plants by the fusion of pre-existing domains.


Assuntos
Carbono-Carbono Liases/genética , Embriófitas/genética , Evolução Molecular , Filogenia , Proteínas de Plantas/genética , Alcanos/metabolismo , Sequência de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis , Regulação da Expressão Gênica de Plantas , Ceras/metabolismo
13.
Trends Biotechnol ; 39(4): 370-380, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33451822

RESUMO

Bioelectrochemical technologies such as electro-fermentation and microbial CO2 electrosynthesis are emerging interdisciplinary technologies that can produce renewable fuels and chemicals (such as carboxylic acids). The benefits of electrically driven bioprocesses include improved production rate, selectivity, and carbon conversion efficiency. However, the accumulation of products can lead to inhibition of biocatalysts, necessitating further effort in separating products. The recent discovery of a new photoenzyme, capable of converting carboxylic acids to bio-alkanes, has offered an opportunity for system integration, providing a promising approach for simultaneous product separation and valorisation. Combining the strengths of photo/bio/electrochemical catalysis, we discuss an innovative circular cascading system that converts biomass and CO2 to value-added bio-alkanes (CnH2n+2, n = 2 to 5) whilst achieving carbon circularity.


Assuntos
Alcanos , Biomassa , Dióxido de Carbono , Eletroquímica , Alcanos/metabolismo , Dióxido de Carbono/metabolismo , Catálise
14.
PLoS One ; 16(1): e0243976, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33493159

RESUMO

Due to the inefficient reproduction of microorganisms in oxygen-deprived environments of the reservoir, the applications of microbial enhanced oil recovery (MEOR) are restricted. To overcome this problem, a new type of air-assisted MEOR process was investigated. Three compounding oil degradation strains were screened using biochemical experiments. Their performances in bacterial suspensions with different amounts of dissolved oxygen were evaluated. Water flooding, microbial flooding and air-assisted microbial flooding core flow experiments were carried out. Carbon distribution curve of biodegraded oil with different oxygen concentration was determined by chromatographic analysis. The long-chain alkanes are degraded by microorganisms. A simulation model was established to take into account the change in oxygen concentration in the reservoir. The results showed that the optimal dissolved oxygen concentration for microbial growth was 4.5~5.5mg/L. The main oxygen consumption in the reservoir happened in the stationary and declining phases of the microbial growth systems. In order to reduce the oxygen concentration to a safe level, the minimum radius of oxygen consumption was found to be about 145m. These results demonstrate that the air-assisted MEOR process can overcome the shortcomings of traditional microbial flooding techniques. The findings of this study can help for better understanding of microbial enhanced oil recovery and improving the efficiency of microbial oil displacement.


Assuntos
Alcanos/metabolismo , Bactérias , Biodegradação Ambiental , Campos de Petróleo e Gás/microbiologia , Petróleo/microbiologia , Bacillus/crescimento & desenvolvimento , Bacillus/isolamento & purificação , Bacillus/metabolismo , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Bactérias/metabolismo , Enterobacter/crescimento & desenvolvimento , Enterobacter/isolamento & purificação , Enterobacter/metabolismo , Fermentação , Oxigênio/metabolismo , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo
15.
Plant Physiol Biochem ; 159: 312-321, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33421907

RESUMO

Poa pratensis is a perennial turfgrass used worldwide. However, shortage of irrigation and drought induced by climate change adversely affect plant growth and turf quality. Cuticular wax covers plant aerial parts and plays important roles in decreasing plant water loss under drought-stressed conditions. Previous research proposed two candidate genes that were involved in wax very-long-chain alkane biosynthesis based on the transcriptome of Poa pratensis leaf. Here, one of the candidate genes, PpCER1-2 was further characterized. A subcellular localization study revealed that PpCER1-2 was localized on the endoplasmic reticulum. The expression of PpCER1-2 could be induced by drought and salt stresses. Overexpression of PpCER1-2 in Brachypodium distachyon increased the alkane amount, whereas decreased the amounts of primary alcohols and total wax. The relative abundance of C25 and C27 alkane and C26 aldehyde increased significantly, but the relative abundance of C29 and C31 alkane and C28 aldehyde decreased. Meanwhile, PpCER1-2 overexpression lines exhibited reduced cuticle permeability and enhanced drought tolerance. These results suggested that PpCER1-2 relatively promoted alkane biosynthesis by converting more very long chain fatty acids precursors into the decarbonylation pathway from the acyl-reduction pathway. Taken together, our data suggest that PpCER1-2 is involved in wax alkane biosynthesis in P. pratensis and plays important roles in improving plant drought tolerance.


Assuntos
Alcanos , Secas , Poa , Estresse Fisiológico , Ceras , Alcanos/metabolismo , Regulação da Expressão Gênica de Plantas , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poa/genética , Poa/metabolismo , Estresse Fisiológico/genética , Ceras/metabolismo
16.
J Gen Appl Microbiol ; 67(1): 9-14, 2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33100277

RESUMO

The yeast Yarrowia lipolytica assimilates hydrophobic compounds, such as n-alkanes and fatty acids, as sole carbon and energy sources. It has been shown that the acyl-CoA synthetase (ACS) genes, FAT1 and FAA1, are involved in the activation of fatty acids produced during the metabolism of n-alkanes, but the ACS genes that are involved in the metabolism of fatty acids from the culture medium remains to be identified. In this paper, we have identified the ACS genes involved in the utilization of exogenous fatty acids. RNA-seq analysis and qRT-PCR revealed that the transcript levels of the peroxisomal ACS-like protein-encoding genes AAL4 and AAL7 were increased in the presence of oleic acid. The single deletion mutant of AAL4 or AAL7 and double deletion mutant of AAL4 and AAL7 did not show any defects in the growth on the medium containing glucose, glycerol, n-alkanes, or fatty acids. In contrast, the mutant with deletion of seven genes, FAA1, FAT1-FAT4, AAL4, and AAL7, showed severe growth defects on the medium containing dodecanoic acid or oleic acid. These results suggest that Aal4p and Aal7p play important roles in the metabolism of exogenous fatty acids in collaboration with Faa1p and Fat1p-Fat4p.


Assuntos
Coenzima A Ligases/metabolismo , Ácidos Graxos/metabolismo , Yarrowia/genética , Yarrowia/metabolismo , Alcanos/metabolismo , Coenzima A Ligases/genética , Proteínas de Transporte de Ácido Graxo/genética , Proteínas de Transporte de Ácido Graxo/metabolismo , Deleção de Genes , Regulação Fúngica da Expressão Gênica , Glicerol/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética
17.
Ecotoxicol Environ Saf ; 209: 111789, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33340957

RESUMO

Yeasts are the most predominant petroleum hydrocarbon-degrading fungi isolated from petroleum-contaminated soil. However, information of the transmembrane transport of petroleum hydrocarbon into yeast cells is limited. The present study was designed to explore the transmembrane transport mechanisms of the typical petroleum hydrocarbon n-hexadecane in Candida tropicalis cells with petroleum hydrocarbon biodegradation potential. Yeast cells were treated with n-hexadecane in different scenarios, and the percentage of intracellular n-hexadecane and transport dynamics were investigated accordingly. The intracellular concentration of n-hexadecane increased within 15 min, and transportation was inhibited by NaN3, an ATPase inhibitor. The uptake kinetics of n-hexadecane were well fitted by the Michaelis-Menten model, and Kt values ranged from 152.49 to 194.93 mg/L. All these findings indicated that n-hexadecane might cross the yeast cells in an energy-dependent manner and exhibit an affinity with the cell transport system. Moreover, the differentially expressed membrane proteins induced by n-hexadecane were identified and quantified by tandem mass tag labeling coupled with liquid chromatography tandem mass spectrometry analysis. The proteome analysis results demonstrated that energy production and conversion accounted for a large proportion of the functional classifications of the differentially expressed proteins, providing further evidence that sufficient energy supply is essential for transmembrane transport. Protein functional analysis also suggested that differentially expressed proteins associated with transmembrane transport processes are clearly enriched in endocytosis and phagosome pathways (p < 0.05), and the analysis supported the notion that the underlying transmembrane transport mechanism might be associated with endocytosis and phagosome pathways, revealing a new mechanism of n-hexadecane internalization by Candida tropicalis.


Assuntos
Alcanos/metabolismo , Biodegradação Ambiental , Candida tropicalis/metabolismo , Hidrocarbonetos/metabolismo , Cinética , Redes e Vias Metabólicas , Petróleo/análise , Proteoma/metabolismo , Proteômica , Leveduras/metabolismo
18.
Food Chem ; 338: 127684, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32916584

RESUMO

Oleocellosis is a physiological disorder causing blemishes on fruit surface. This study investigated the influence of oleocellosis on the membrane fatty acids and wax in lemon fruit rinds at the morphological, physiological, metabolic and molecular levels by using a variety with a high incidence rate of oleocellosis (green lemon). Oleocellosis-damaged rinds showed loose and flaky wax layers with more fissures on the surface, as well as higher contents of C16 and C18 fatty acids and very long chain (VLC) fatty alkanes while lower contents of VLC fatty aldehydes. The main differentially expressed genes, including FabZ, FAD2 and SAD6 involved in the accumulation of C16 and C18 fatty acids and CER1 involved in the transformation of VLC fatty aldehydes to VLC fatty alkanes, were up-regulated by oleocellosis. These results indicate that oleocellosis accelerates the accumulation of membrane free fatty acids and transformation of VLC fatty aldehydes to VLC fatty alkanes.


Assuntos
Citrus/metabolismo , Ácidos Graxos/metabolismo , Ceras/metabolismo , Alcanos/metabolismo , Citrus/genética , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Dessaturases/metabolismo , Ácidos Graxos/análise , Frutas/anatomia & histologia , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Análise de Componente Principal , Ceras/análise , Ceras/química
19.
Environ Microbiol ; 23(2): 530-541, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32367670

RESUMO

Methyl-coenzyme M reductase (MCR) has been originally identified to catalyse the final step of the methanogenesis pathway. About 20 years ago anaerobic methane-oxidizing archaea (ANME) were discovered that use MCR enzymes to activate methane. ANME thrive at the thermodynamic limit of life, are slow-growing, and in most cases form syntrophic consortia with sulfate-reducing bacteria. Recently, archaea that have the ability to anaerobically oxidize non-methane multi-carbon alkanes such as ethane and n-butane were described in both enrichment cultures and environmental samples. These anaerobic multi-carbon alkane-oxidizing archaea (ANKA) use enzymes homologous to MCR named alkyl-coenzyme M reductase (ACR). Here we review the recent progresses on the diversity, distribution and functioning of both ANME and ANKA by presenting a detailed MCR/ACR-based phylogeny, compare their metabolic pathways and discuss the gaps in our knowledge of physiology of these organisms. To improve our understanding of alkane oxidation in archaea, we identified three directions for future research: (i) expanding cultivation attempts to validate omics-based metabolic models of yet-uncultured organisms, (ii) performing biochemical and structural analyses of key enzymes to understand thermodynamic and steric constraints and (iii) investigating the evolution of anaerobic alkane metabolisms and their impact on biogeochemical cycles.


Assuntos
Alcanos/metabolismo , Archaea/enzimologia , Proteínas Arqueais/metabolismo , Oxirredutases/metabolismo , Anaerobiose , Archaea/química , Archaea/classificação , Archaea/genética , Proteínas Arqueais/química , Proteínas Arqueais/genética , Oxirredução , Oxirredutases/química , Oxirredutases/genética , Filogenia
20.
Nat Commun ; 11(1): 6198, 2020 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-33273473

RESUMO

Alka(e)nes are ideal fuel components for aviation, long-distance transport, and shipping. They are typically derived from fossil fuels and accounting for 24% of difficult-to-eliminate greenhouse gas emissions. The synthesis of alka(e)nes in Yarrowia lipolytica from CO2-neutral feedstocks represents an attractive alternative. Here we report that the high-titer synthesis of alka(e)nes in Yarrowia lipolytica harboring a fatty acid photodecarboxylase (CvFAP) is enabled by a discovered pathway. We find that acyl-CoAs, rather than free fatty acids (FFAs), are the preferred substrate for CvFAP. This finding allows us to debottleneck the pathway and optimize fermentation conditions so that we are able to redirect 89% of acyl-CoAs from the synthesis of neutral lipids to alka(e)nes and reach titers of 1.47 g/L from glucose. Two other CO2-derived substrates, wheat straw and acetate, are also demonstrated to be effective in producing alka(e)nes. Overall, our technology could advance net-zero emissions by providing CO2-neutral and energy-dense liquid biofuels.


Assuntos
Alcanos/metabolismo , Alcenos/metabolismo , Yarrowia/metabolismo , Acil Coenzima A/metabolismo , Dióxido de Carbono/metabolismo , Esterases/metabolismo , Fermentação , Dosagem de Genes , Gases de Efeito Estufa , Engenharia Metabólica , Redes e Vias Metabólicas , Especificidade por Substrato
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