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1.
J Environ Sci (China) ; 147: 268-281, 2025 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-39003046

RESUMO

The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies. In this study, we evaluated the removal of a gaseous mixture containing toluene, m-xylene, ethylbenzene, cyclohexane, butane, pentane, hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions. For the real-time measurement of hydrocarbons, a novel systematic approach was implemented using Selected-Ion Flow Tube Mass Spectrometry (SIFT-MS). The effect of the carbon source (∼9.5 ppmv) on (i) the bioreactors' performance (BR1: dosed with only cyclohexane as a single hydrocarbon versus BR2: dosed with a mixture of the 8 hydrocarbons) and (ii) the evolution of microbial communities over time were investigated. The results showed that cyclohexane reached a maximum removal efficiency (RE) of 53% ± 4% in BR1. In BR2, almost complete removal of toluene, m-xylene and ethylbenzene, being the most water-soluble and easy-to-degrade carbon sources, was observed. REs below 32% were obtained for the remaining compounds. By exposing the microbial consortium to only the five most recalcitrant hydrocarbons, REs between 45% ± 5% and 98% ± 1% were reached. In addition, we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed. The abundance of species belonging to the genus Rhodococcus was below 10% in all bioreactors at the end of the experiments. This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors, along with a systematic approach for the development of SIFT-MS methods.


Assuntos
Biodegradação Ambiental , Reatores Biológicos , Hidrocarbonetos , Rhodococcus , Rhodococcus/metabolismo , Reatores Biológicos/microbiologia , Hidrocarbonetos/metabolismo , Carbono/metabolismo , Poluentes Atmosféricos/metabolismo , Poluentes Atmosféricos/análise , Espectrometria de Massas , Tolueno/metabolismo , Xilenos/metabolismo , Butanos/metabolismo , Derivados de Benzeno , Pentanos
2.
Environ Sci Pollut Res Int ; 31(33): 46002-46022, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38980484

RESUMO

Mining-related lead (Pb) pollution of the soil poses serious hazards to ecosystems and living organisms, including humans. Improved heavy metal phytoremediation efficacy, achieved by using phytostabilizing plants assisted by plant-growth-promoting (PGP) microorganisms, has been presented as an effective strategy for remediating polluted soils. The objective of this research was to examine the response and potential of the plant-growth-promoting bacterium LMR356, a Rhodococcus qingshengii strain isolated from an abandoned mining soil, under lead stress conditions. Compared to non-contaminated culture media, the presence of lead induced a significant decrease in auxin production (from 21.17 to 2.65 µg mL-1) and phosphate solubilization (from 33.60 to 8.22 mg L-1), whereas other PGP traits increased drastically, such as 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity (from 38.17 to 71.37 nmol mg-1 h-1 α-ketobutyrate), siderophore production (from 69 to 83%), exopolysaccharide production (from 1952.28 to 3637.72 mg mL-1), biofilm formation, and motility. We, therefore, investigated the behavior of Sulla spinosissima L. in the presence or absence of this strain under a variety of experimental conditions. Under hydroponic conditions, Sulla plants showed endurance to varying lead concentrations (500-1000 µM). Inoculation of plants with Rhodococcus qingshengii strain LMR356 enhanced plant tolerance, as demonstrated by the increase in plant biomass (ranging from 14.41 to 79.12%) compared to non-inoculated Pb-stressed and non-stressed control plants. Antioxidant enzyme activities (increasing by -42.71 to 126.8%) and chlorophyll (383.33%) and carotenoid (613.04%) content were also augmented. In addition to its impact on plant lead tolerance, strain LMR356 showed a growth-promoting effect on Sulla plants when cultivated in sterilized non-contaminated sand. Parameters such as plant biomass (16.57%), chlorophyll (24.14%), and carotenoid (30%) contents, as well as ascorbate peroxidase (APX), peroxidase (POD), and catalase (CAT) activities, were all elevated compared to non-inoculated plants. Furthermore, when the same plant species was cultivated in highly polluted soil, inoculation increased plant biomass and improved its physiological properties. These findings demonstrate that LMR356 is a phytobeneficial bacterial strain capable of enhancing Sulla growth under normal conditions and improving its heavy metal tolerance in multi-polluted soils. Thus, it can be considered a promising biofertilizer candidate for growing Sulla spinosissima L. or other selected plants intended for application in restoration and stabilization initiatives aimed at reviving and safeguarding environmentally compromised and polluted soils after mining activities.


Assuntos
Biodegradação Ambiental , Chumbo , Rhodococcus , Poluentes do Solo , Rhodococcus/metabolismo , Microbiologia do Solo , Desenvolvimento Vegetal/efeitos dos fármacos
3.
Mol Biol Rep ; 51(1): 817, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39012451

RESUMO

BACKGROUND: Nitrile Hydratase (NHase) is one of the most important industrial enzyme widely used in the petroleum exploitation field. The enzyme, composed of two unrelated α- and ß-subunits, catalyzes the conversion of acrylonitrile to acrylamide, releasing a significant amount of heat and generating the organic solvent product, acrylamide. Both the heat and acrylamide solvent have an impact on the structural stability of NHase and its catalytic activity. Therefore, enhancing the stress resistance of NHase to toxic substances is meaningful for the petroleum industry. METHODS AND RESULTS: To improve the thermo-stability and acrylamide tolerance of NHase, the two subunits were fused in vivo using SpyTag and SpyCatcher, which were attached to the termini of each subunit in various combinations. Analysis of the engineered strains showed that the C-terminus of ß-NHase is a better fusion site than the N-terminus, while the C-terminus of α-NHase is the most suitable site for fusion with a larger protein. Fusion of SpyTag and SpyCatcher to the C-terminus of ß-NHase and α-NHase, respectively, led to improved acrylamide tolerance and a slight enhancement in the thermo-stability of one of the engineered strains, NBSt. CONCLUSION: These results indicate that in vivo ligation of different subunits using SpyTag/SpyCatcher is a valuable strategy for enhancing subunit interaction and improving stress tolerance.


Assuntos
Hidroliases , Rhodococcus , Rhodococcus/enzimologia , Rhodococcus/genética , Hidroliases/metabolismo , Hidroliases/genética , Hidroliases/química , Estabilidade Enzimática , Estresse Fisiológico , Acrilamida/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Subunidades Proteicas/metabolismo , Subunidades Proteicas/genética
4.
Molecules ; 29(14)2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-39064956

RESUMO

Terpenoids and steroids are secondary plant and animal metabolites and are widely used to produce highly effective pharmacologically significant compounds. One of the promising approaches to the transformation of these compounds to form bioactive metabolites is their transformation using microorganisms. Rhodococcus spp. are one of the most developed objects in biotechnology due to their exceptional metabolic capabilities and resistance to extreme environmental conditions. In this review, information on the processes of biotransformation of terpenoid and steroid compounds by actinomycetes of the genus Rhodococcus and their molecular genetic bases are most fully collected and analyzed for the first time. Examples of the use of both native whole-cell catalysts and mutant strains and purified enzyme systems for the production of derivatives of terpenoids and steroids are given.


Assuntos
Biotransformação , Rhodococcus , Esteroides , Terpenos , Rhodococcus/metabolismo , Rhodococcus/genética , Terpenos/metabolismo , Terpenos/química , Esteroides/metabolismo , Esteroides/química , Actinobacteria/metabolismo , Actinobacteria/genética
5.
Appl Environ Microbiol ; 90(7): e0041624, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-38837369

RESUMO

Ethylene glycol (EG) is a widely used industrial chemical with manifold applications and also generated in the degradation of plastics such as polyethylene terephthalate. Rhodococcus jostii RHA1 (RHA1), a potential biocatalytic chassis, grows on EG. Transcriptomic analyses revealed four clusters of genes potentially involved in EG catabolism: the mad locus, predicted to encode mycofactocin-dependent alcohol degradation, including the catabolism of EG to glycolate; two GCL clusters, predicted to encode glycolate and glyoxylate catabolism; and the mft genes, predicted to specify mycofactocin biosynthesis. Bioinformatic analyses further revealed that the mad and mft genes are widely distributed in mycolic acid-producing bacteria such as RHA1. Neither ΔmadA nor ΔmftC RHA1 mutant strains grew on EG but grew on acetate. In resting cell assays, the ΔmadA mutant depleted glycolaldehyde but not EG from culture media. These results indicate that madA encodes a mycofactocin-dependent alcohol dehydrogenase that initiates EG catabolism. In contrast to some mycobacterial strains, the mad genes did not appear to enable RHA1 to grow on methanol as sole substrate. Finally, a strain of RHA1 adapted to grow ~3× faster on EG contained an overexpressed gene, aldA2, predicted to encode an aldehyde dehydrogenase. When incubated with EG, this strain accumulated lower concentrations of glycolaldehyde than RHA1. Moreover, ecotopically expressed aldA2 increased RHA1's tolerance for EG further suggesting that glycolaldehyde accumulation limits growth of RHA1 on EG. Overall, this study provides insights into the bacterial catabolism of small alcohols and aldehydes and facilitates the engineering of Rhodococcus for the upgrading of plastic waste streams.IMPORTANCEEthylene glycol (EG), a two-carbon (C2) alcohol, is produced in high volumes for use in a wide variety of applications. There is burgeoning interest in understanding and engineering the bacterial catabolism of EG, in part to establish circular economic routes for its use. This study identifies an EG catabolic pathway in Rhodococcus, a genus of bacteria well suited for biocatalysis. This pathway is responsible for the catabolism of methanol, a C1 feedstock, in related bacteria. Finally, we describe strategies to increase the rate of degradation of EG by increasing the transformation of glycolaldehyde, a toxic metabolic intermediate. This work advances the development of biocatalytic strategies to transform C2 feedstocks.


Assuntos
Proteínas de Bactérias , Etilenoglicol , Rhodococcus , Rhodococcus/metabolismo , Rhodococcus/genética , Etilenoglicol/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Glicolatos/metabolismo , Glioxilatos/metabolismo , Álcool Desidrogenase/metabolismo , Álcool Desidrogenase/genética , Peptídeos
6.
Chemosphere ; 361: 142489, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38825247

RESUMO

Microorganisms have great potential for bioremediation as they have powerful enzymes and machineries that can transform xenobiotics. The use of a microbial consortium provides more advantages in application point of view than pure cultures due to cross-feeding, adaptations, functional redundancies, and positive interactions among the organisms. In this study, we screened about 107 isolates for their ability to degrade dyes in aerobic conditions and without additional carbon source. From our screening results, we finally limited our synthetic consortium to Gordonia and Rhodococcus isolates. The synthetic consortium was trained and optimized for azo dye degradation using sequential treatment of small aromatic compounds such as phenols that act as selective pressure agents. After four rounds of optimization with different aims for each round, the consortium was able to decolorize and degrade various dyes after 48 h (80%-100% for brilliant black bn, methyl orange, and chromotrop 2b; 50-70% for orange II and reactive orange 16; 15-30% for chlorazol black e, reactive red 120, and allura red ac). Through rational approaches, we can show that treatment with phenolic compounds at micromolar dosages can significantly improve the degradation of bulky dyes and increase its substrate scope. Moreover, our selective pressure approach led to the production of various dye-degrading enzymes as azoreductase, laccase-like, and peroxidase-like activities were detected from the phenol-treated consortium. Evidence of degradation was also shown as metabolites arising from the degradation of methyl red and brilliant black bn were detected using HPLC and LC-MS analysis. Therefore, this study establishes the importance of rational and systematic screening and optimization of a consortium. Not only can this approach be applied to dye degradation, but this study also offers insights into how we can fully maximize microbial consortium activity for other applications, especially in biodegradation and biotransformation.


Assuntos
Compostos Azo , Biodegradação Ambiental , Corantes , Consórcios Microbianos , Rhodococcus , Corantes/química , Corantes/metabolismo , Compostos Azo/química , Compostos Azo/metabolismo , Rhodococcus/metabolismo , Bactéria Gordonia/metabolismo , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/química , Fenóis/metabolismo , Fenóis/química , Nitrorredutases/metabolismo
7.
Arch Microbiol ; 206(7): 313, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38900186

RESUMO

Phenols are highly toxic chemicals that are extensively used in industry and produce large amounts of emissions. Notably, phenols released into the soil are highly persistent, causing long-term harm to human health and the environment. In this study, a gram-positive, aerobic, and rod-shaped bacterial strain, Z13T, with efficient phenol degradation ability, was isolated from the soil of sugarcane fields. Based on the physiological properties and genomic features, strain Z13T is considered as a novel species of the genus Rhodococcus, for which the name Rhodococcus sacchari sp. nov. is proposed. The type strain is Z13T (= CCTCC AB 2022327T = JCM 35797T). This strain can use phenol as its sole carbon source. Z13T was able to completely degrade 1200 mg/L phenol within 20 h; the maximum specific growth rate was µmax = 0.93174 h-1, and the maximum specific degradation rate was qmax = 0.47405 h-1. Based on whole-genome sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, strain Z13T contains a series of phenol degradation genes, including dmpP, CatA, dmpB, pcaG, and pcaH, and can metabolize aromatic compounds. Moreover, the potential of strain Z13T for soil remediation was investigated by introducing Z13T into simulated phenol-contaminated soil, and the soil microbial diversity was analyzed. The results showed that 100% of the phenol in the soil was removed within 7.5 d. Furthermore, microbial diversity analysis revealed an increase in the relative species richness of Oceanobacillus, Chungangia, and Bacillus.


Assuntos
Biodegradação Ambiental , Fenol , Filogenia , RNA Ribossômico 16S , Rhodococcus , Microbiologia do Solo , Poluentes do Solo , Rhodococcus/metabolismo , Rhodococcus/genética , Rhodococcus/classificação , Rhodococcus/crescimento & desenvolvimento , Rhodococcus/isolamento & purificação , Poluentes do Solo/metabolismo , Fenol/metabolismo , RNA Ribossômico 16S/genética , Saccharum/metabolismo , Saccharum/microbiologia , Saccharum/crescimento & desenvolvimento , Solo/química , Genoma Bacteriano
8.
Arch Microbiol ; 206(7): 300, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38861201

RESUMO

Microorganisms produce diverse classes of metabolites under various physiological conditions. Many bacterial strains have been reported to carry out the process of desulfurization in a cost-effective manner by converting dibenzothiophene (DBT) into 2-hydroxybiphenyl (2-HBP) and then using the 2-HBP as a carbon source for growth and development. Key rate-limiting factors and an increased concentration of 2HBP (400 µM) affect the biodesulfurization activity of bacteria through the produced metabolites. Thus, this study was designed to explore the nature of the metabolites produced by Rhodococcus erythropolis in the presence of DBT and 2HBP supplemented with a culture medium. A total of 330 metabolites were detected, and the key metabolites identified were 11Z-eicosaenoyl-EA, 1-carboxyethylisoleucine, 1(3)-glyceryl-PGF2alpha, taurine, 2-hydroxynicotinic acid, 4,4-dimethyl-14alpha-hydroxymethyl-5alpha-cholest-8-en-3beta-ol, and 10-nitrooleic acid. The supplementation of DBT and DBT-2HBP resulted in the differential regulation of these metabolites, either through downregulation or overexpression. Furthermore, at high concentrations of 2-HBP, 1-carboxyethylisoleucine, taurine, 2-hydroxynicotinic acid, and nicotinic acid were upregulated. This work proposes that the identified metabolites may play a role in bacteria-mediated desulphurization and could be beneficial in developing a cost-effective method of desulphurization for refining petroleum.


Assuntos
Compostos de Bifenilo , Petróleo , Rhodococcus , Tiofenos , Rhodococcus/metabolismo , Rhodococcus/crescimento & desenvolvimento , Petróleo/metabolismo , Compostos de Bifenilo/metabolismo , Tiofenos/metabolismo , Biodegradação Ambiental , Meios de Cultura/química , Meios de Cultura/metabolismo , Enxofre/metabolismo
9.
J Hazard Mater ; 474: 134776, 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-38852255

RESUMO

Phthalate esters (PAEs) are widely used as plasticizers and cause serious complex pollution problem in environment. Thus, strains with efficient ability to simultaneously degrade various PAEs are required. In this study, a newly isolated strain Rhodococcus sp. AH-ZY2 can degrade 500 mg/L Di-n-octyl phthalate completely within 16 h and other 500 mg/L PAEs almost completely within 48 h at 37 °C, 180 rpm, and 2 % (v/v) inoculum size of cultures with a OD600 of 0.8. OD600 = 0.8, 2 % (v/v). Twenty genes in its genome were annotated as potential esterase and four of them (3963, 4547, 5294 and 5359) were heterogeneously expressed and characterized. Esterase 3963 and 4547 is a type I PAEs esterase that hydrolyzes PAEs to phthalate monoesters. Esterase 5294 is a type II PAEs esterase that hydrolyzes phthalate monoesters to phthalate acid (PA). Esterase 5359 is a type III PAEs esterase that simultaneously degrades various PAEs to PA. Molecular docking results of 5359 suggested that the size and indiscriminate binding feature of spacious substrate binding pocket may contribute to its substrate versatility. AH-ZY2 is a potential strain for efficient remediation of PAEs complex pollution in environment. It is first to report an esterase that can efficiently degrade mixed various PAEs.


Assuntos
Biodegradação Ambiental , Esterases , Ésteres , Simulação de Acoplamento Molecular , Ácidos Ftálicos , Rhodococcus , Rhodococcus/metabolismo , Rhodococcus/genética , Rhodococcus/enzimologia , Ácidos Ftálicos/metabolismo , Ácidos Ftálicos/química , Esterases/metabolismo , Esterases/genética , Ésteres/metabolismo , Ésteres/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Plastificantes/metabolismo
10.
Arch Microbiol ; 206(7): 328, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38935150

RESUMO

Marine hydrocarbonoclastic bacteria can use polycyclic aromatic hydrocarbons as carbon and energy sources, that makes these bacteria highly attractive for bioremediation in oil-polluted waters. However, genomic and metabolic differences between species are still the subject of study to understand the evolution and strategies to degrade PAHs. This study presents Rhodococcus ruber MSA14, an isolated bacterium from marine sediments in Baja California, Mexico, which exhibits adaptability to saline environments, a high level of intrinsic pyrene tolerance (> 5 g L- 1), and efficient degradation of pyrene (0.2 g L- 1) by 30% in 27 days. Additionally, this strain demonstrates versatility by using naphthalene and phenanthrene as individual carbon sources. The genome sequencing of R. ruber MSA14 revealed a genome spanning 5.45 Mbp, a plasmid of 72 kbp, and three putative megaplasmids, lengths between 110 and 470 Kbp. The bioinformatics analysis of the R. ruber MSA14 genome revealed 56 genes that encode enzymes involved in the peripheral and central pathways of aromatic hydrocarbon catabolism, alkane, alkene, and polymer degradation. Within its genome, R. ruber MSA14 possesses genes responsible for salt tolerance and siderophore production. In addition, the genomic analysis of R. ruber MSA14 against 13 reference genomes revealed that all compared strains have at least one gene involved in the alkanes and catechol degradation pathway. Overall, physiological assays and genomic analysis suggest that R. ruber MSA14 is a new haloalkalitolerant and hydrocarbonoclastic strain toward a wide range of hydrocarbons, making it a promising candidate for in-depth characterization studies and bioremediation processes as part of a synthetic microbial consortium, as well as having a better understanding of the catabolic potential and functional diversity among the Rhodococci group.


Assuntos
Biodegradação Ambiental , Genoma Bacteriano , Genômica , Sedimentos Geológicos , Hidrocarbonetos Policíclicos Aromáticos , Rhodococcus , Rhodococcus/genética , Rhodococcus/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Sedimentos Geológicos/microbiologia , Naftalenos/metabolismo , Filogenia , Fenantrenos/metabolismo , Tolerância ao Sal , Pirenos
11.
Curr Microbiol ; 81(7): 218, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38856763

RESUMO

Atractylodes macrocephala Koidz (AMK) is a perennial herb from the plant family Asteraceae (formerly Compositae). This herb is mainly distributed in mountainous wetlands in Zhejiang, Sichuan, Yunnan, and Hunan provinces of China. Its medicinal production and quality, however, are severely impacted by root rot disease. In our previous study, endophytic bacterium designated AM201 exerted a high biocontrol effect on the root rot disease of AMK. However, the molecular mechanisms underlying this effect remain unclear. In this study, the identity of strain AM201 as Rhodococcus sp. was determined through analysis of its morphology, physiological and biochemical characteristics, as well as 16S rDNA sequencing. Subsequently, we performed transcriptome sequencing and bioinformatics analysis to compare and analyze the transcriptome profiles of root tissues from two groups: AM201 (AMK seedlings inoculated with Fusarium solani [FS] and AM201) and FS (AMK seedlings inoculated with FS alone). We also conducted morphological, physiological, biochemical, and molecular identification analyses for the AM201 strain. We obtained 1,560 differentially expressed genes, including 187 upregulated genes and 1,373 downregulated genes. We screened six key genes (GOLS2, CIPK25, ABI2, egID, PG1, and pgxB) involved in the resistance of AM201 against AMK root rot disease. These genes play a critical role in reactive oxygen species (ROS) clearance, Ca2+ signal transduction, abscisic acid signal inhibition, plant root growth, and plant cell wall defense. The strain AM201 was identified as Rhodococcus sp. based on its morphological characteristics, physiological and biochemical properties, and 16S rDNA sequencing results. The findings of this study could enable to prevent and control root rot disease in AMK and could offer theoretical guidance for the agricultural production of other medicinal herbs.


Assuntos
Atractylodes , Endófitos , Perfilação da Expressão Gênica , Doenças das Plantas , Raízes de Plantas , Rhodococcus , Rhodococcus/genética , Rhodococcus/metabolismo , Rhodococcus/fisiologia , Atractylodes/microbiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Raízes de Plantas/microbiologia , Endófitos/genética , Endófitos/metabolismo , Endófitos/classificação , Endófitos/fisiologia , Endófitos/isolamento & purificação , Transcriptoma , Fusarium/genética , Fusarium/fisiologia , China , RNA Ribossômico 16S/genética
12.
Artigo em Inglês | MEDLINE | ID: mdl-38841989

RESUMO

Opinion 130 deals with a Request for an Opinion asking the Judicial Commission to clarify whether the genus name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate. The Request is approved and an answer is given. The name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate because it is a later homonym of the validly published cyanobacterial name Rhodococcus Hansgirg 1884. The Judicial Commission also clarifies that it has the means to resolve such cases by conserving a name over an earlier homonym. It is concluded that the name Rhodococcus Zopf 1891 (Approved Lists 1980) is significantly more important than the name Rhodococcus Hansgirg 1884 and therefore the former is conserved over the latter. This makes the name Rhodococcus Zopf 1891 (Approved Lists 1980) legitimate.


Assuntos
Rhodococcus , Terminologia como Assunto , Rhodococcus/classificação
13.
Environ Pollut ; 355: 124217, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38797346

RESUMO

Although di(2-ethylhexyl) terephthalate (DOTP) is being widely adopted as a non-phthalate plasticizer, existing research primarily focuses on human and rat toxicity. This leaves a significant gap in our understanding of their impact on microbial communities. This study assessed the biodegradation and toxicity of DOTP on microbes, focusing on its impact on biofilms and microbial metabolism using Rhodococcus ruber as a representative bacterial strain. DOTP is commonly found in mass fractions between 0.6 and 20% v/v in various soft plastic products. This study used polyvinyl chloride films (PVC) with varying DOTP concentrations (range 1-10% v/v) as a surface for analysis of biofilm growth. Cell viability and bacterial stress responses were tested using LIVE/DEAD™ BacLight™ Bacterial Viability Kit and by the detection of reactive oxygen species using CellROX™ Green Reagent, respectively. An increase in the volume of dead cells (in the plastisphere biofilm) was observed with increasing DOTP concentrations in experiments using PVC films, indicating the potential negative impact of DOTP on microbial communities. Even at a relatively low concentration of DOTP (1%), signs of stress in the microbes were noticed, while concentrations above 5% compromised their ability to survive. This research provides a new understanding of the environmental impacts of alternative plasticizers, prompting the need for additional research into their wider effects on both the environment and human health.


Assuntos
Biodegradação Ambiental , Biofilmes , Ácidos Ftálicos , Plastificantes , Espécies Reativas de Oxigênio , Plastificantes/toxicidade , Biofilmes/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Ácidos Ftálicos/toxicidade , Ácidos Ftálicos/metabolismo , Rhodococcus/metabolismo , Rhodococcus/efeitos dos fármacos , Cloreto de Polivinila/toxicidade , Dietilexilftalato/toxicidade
14.
Biosci Biotechnol Biochem ; 88(8): 979-982, 2024 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-38794895

RESUMO

To clarify the growth mechanisms of Rhodococcus in the alkane phase, we measured oxygen utilization in the alkane phase. The results showed that dissolved oxygen decreased significantly when viable cells were present in the alkane phase. The findings suggested that Rhodococcus strains can grow in alkanes and utilize the resident dissolved oxygen.


Assuntos
Alcanos , Oxigênio , Rhodococcus , Rhodococcus/metabolismo , Rhodococcus/crescimento & desenvolvimento , Alcanos/metabolismo , Oxigênio/metabolismo , Água/química , Água/metabolismo
15.
J Microbiol Biotechnol ; 34(6): 1356-1364, 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38754998

RESUMO

Isoamyl fatty acid esters (IAFEs) are widely used as fruity flavor compounds in the food industry. In this study, various IAFEs were synthesized from isoamyl alcohol and various fatty acids using a cutinase enzyme (Rcut) derived from Rhodococcus bacteria. Rcut was immobilized on methacrylate divinylbenzene beads and used to synthesize isoamyl acetate, butyrate, hexanoate, octanoate, and decanoate. Among them, Rcut synthesized isoamyl butyrate (IAB) most efficiently. Docking model studies showed that butyric acid was the most suitable substrate in terms of binding energy and distance from the active site serine (Ser114) γ-oxygen. Up to 250 mM of IAB was synthesized by adjusting reaction conditions such as substrate concentration, reaction temperature, and reaction time. When the enzyme reaction was performed by reusing the immobilized enzyme, the enzyme activity was maintained at least six times. These results demonstrate that the immobilized Rcut enzyme can be used in the food industry to synthesize a variety of fruity flavor compounds, including IAB.


Assuntos
Hidrolases de Éster Carboxílico , Enzimas Imobilizadas , Aromatizantes , Simulação de Acoplamento Molecular , Rhodococcus , Enzimas Imobilizadas/metabolismo , Enzimas Imobilizadas/química , Rhodococcus/enzimologia , Rhodococcus/metabolismo , Aromatizantes/metabolismo , Aromatizantes/química , Hidrolases de Éster Carboxílico/metabolismo , Hidrolases de Éster Carboxílico/química , Ésteres/metabolismo , Ésteres/química , Pentanóis/metabolismo , Pentanóis/química , Ácidos Graxos/metabolismo , Ácidos Graxos/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Temperatura , Especificidade por Substrato , Ácido Butírico/metabolismo , Ácido Butírico/química , Domínio Catalítico
16.
Environ Sci Pollut Res Int ; 31(24): 35332-35352, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38727971

RESUMO

Petroleum hydrocarbons are a stubborn pollutant that is difficult to degrade globally, and plant-microbial degradation is the main way to solve this type of pollutant. In this study, the physiological and ecological responses of alfalfa to petroleum hydrocarbons in different concentrations of petroleum hydrocarbon-contaminated soil with KB1 (Rhodococcus erythropolis) were analyzed and determined by laboratory potting techniques. The growth of alfalfa (CK) and alfalfa with KB1 (JZ) in different concentrations of petroleum hydrocarbons contaminated soil was compared and analyzed. The results of the CK group showed that petroleum hydrocarbons could significantly affect the activity of alfalfa antioxidant enzyme system, inhibit the development of alfalfa roots and the normal growth of plants, especially in the high-concentration group. KB1 strain had the ability to produce IAA, form biofilm, fix nitrogen, produce betaine and ACC deaminase, and the addition of KB1 could improve the growth traits of alfalfa in the soil contaminated with different concentrations of petroleum hydrocarbons, the content of soluble sugars in roots, and the stress resistance and antioxidant enzyme activities of alfalfa. In addition, the degradation kinetics of the strain showed that the degradation rate of petroleum could reach 75.2% after soaking with KB1. Furthermore, KB1 can efficiently degrade petroleum hydrocarbons in advance and significantly alleviate the damage of high concentration of petroleum hydrocarbons to plant roots. The results showed that KB1 strains and alfalfa plants could effectively enhance the degradation of petroleum hydrocarbons, which provided new ideas for improving bioremediation strategies.


Assuntos
Biodegradação Ambiental , Hidrocarbonetos , Medicago sativa , Petróleo , Rhodococcus , Poluentes do Solo , Petróleo/metabolismo , Poluentes do Solo/metabolismo , Rhodococcus/metabolismo , Hidrocarbonetos/metabolismo , Microbiologia do Solo , Raízes de Plantas/metabolismo
17.
Microb Cell Fact ; 23(1): 140, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38760827

RESUMO

BACKGROUND: Quantum Dots (QDs) are fluorescent nanoparticles with exceptional optical and optoelectronic properties, finding widespread utility in diverse industrial applications. Presently, chemically synthesized QDs are employed in solar cells, bioimaging, and various technological domains. However, many applications demand QDs with prolonged lifespans under conditions of high-energy radiation. Over the past decade, microbial biosynthesis of nanomaterials has emerged as a sustainable and cost-effective process. In this context, the utilization of extremophile microorganisms for synthesizing QDs with unique properties has recently been reported. RESULTS: In this study, UV-resistant bacteria were isolated from one of the most extreme environments in Antarctica, Union Glacier at the Ellsworth Mountains. Bacterial isolates, identified through 16 S sequencing, belong to the genera Rhodococcus, Pseudarthrobacter, and Arthrobacter. Notably, Rhodococcus sp. (EXRC-4 A-4), Pseudarthrobacter sp. (RC-2-3), and Arthrobacter sp. (EH-1B-1) tolerate UV-C radiation doses ≥ 120 J/m². Isolated UV-resistant bacteria biosynthesized CdS QDs with fluorescence intensities 4 to 8 times higher than those biosynthesized by E. coli, a mesophilic organism tolerating low doses of UV radiation. Transmission electron microscopy (TEM) analysis determined QD sizes ranging from 6 to 23 nm, and Fourier-transform infrared (FTIR) analysis demonstrated the presence of biomolecules. QDs produced by UV-resistant Antarctic bacteria exhibit high photostability after exposure to UV-B radiation, particularly in comparison to those biosynthesized by E. coli. Interestingly, red fluorescence-emitting QDs biosynthesized by Rhodococcus sp. (EXRC-4 A-4) and Arthrobacter sp. (EH-1B-1) increased their fluorescence emission after irradiation. Analysis of methylene blue degradation after exposure to irradiated QDs biosynthesized by UV-resistant bacteria, indicates that the QDs transfer their electrons to O2 for the formation of reactive oxygen species (ROS) at different levels. CONCLUSIONS: UV-resistant Antarctic bacteria represent a novel alternative for the sustainable generation of nanostructures with increased radiation tolerance-two characteristics favoring their potential application in technologies requiring continuous exposure to high-energy radiation.


Assuntos
Compostos de Cádmio , Pontos Quânticos , Rhodococcus , Raios Ultravioleta , Pontos Quânticos/química , Regiões Antárticas , Compostos de Cádmio/metabolismo , Compostos de Cádmio/química , Rhodococcus/metabolismo , Rhodococcus/genética , Arthrobacter/metabolismo , Arthrobacter/genética , Sulfetos/metabolismo , Sulfetos/química
18.
J Chem Inf Model ; 64(10): 4218-4230, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38684937

RESUMO

Due to its detrimental impact on human health and the environment, regulations demand ultralow sulfur levels on fossil fuels, in particular in diesel. However, current desulfurization techniques are expensive and cannot efficiently remove heteroaromatic sulfur compounds, which are abundant in crude oil and concentrate in the diesel fraction after distillation. Biodesulfurization via the four enzymes of the metabolic 4S pathway of the bacterium Rhodococcus erythropolis (DszA-D) is a possible solution. However, the 4S pathway needs to operate at least 500 times faster for industrial applicability, a goal currently pursued through enzyme engineering. In this work, we unveil the catalytic mechanism of the flavin monooxygenase DszA. Surprisingly, we found that this enzyme follows a recently proposed atypical mechanism that passes through the formation of an N5OOH intermediate at the re side of the cofactor, aided by a well-defined, predominantly hydrophobic O2 pocket. Besides clarifying the unusual chemical mechanism of the complex DszA enzyme, with obvious implications for understanding the puzzling chemistry of flavin-mediated catalysis, the result is crucial for the rational engineering of DszA, contributing to making biodesulfurization attractive for the oil refining industry.


Assuntos
Biocatálise , Rhodococcus , Rhodococcus/enzimologia , Rhodococcus/metabolismo , Modelos Moleculares , Enxofre/metabolismo , Enxofre/química , Oxigenases de Função Mista/metabolismo , Oxigenases de Função Mista/química , Carbono/química , Carbono/metabolismo
19.
J Struct Biol ; 216(2): 108093, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38615726

RESUMO

Many enzymes can self-assemble into higher-order structures with helical symmetry. A particularly noteworthy example is that of nitrilases, enzymes in which oligomerization of dimers into spiral homo-oligomers is a requirement for their enzymatic function. Nitrilases are widespread in nature where they catalyze the hydrolysis of nitriles into the corresponding carboxylic acid and ammonia. Here, we present the Cryo-EM structure, at 3 Å resolution, of a C-terminal truncate nitrilase from Rhodococcus sp. V51B that assembles in helical filaments. The model comprises a complete turn of the helical arrangement with a substrate-intermediate bound to the catalytic cysteine. The structure was solved having added the substrate to the protein. The length and stability of filaments was made more substantial in the presence of the aromatic substrate, benzonitrile, but not for aliphatic nitriles or dinitriles. The overall structure maintains the topology of the nitrilase family, and the filament is formed by the association of dimers in a chain-like mechanism that stabilizes the spiral. The active site is completely buried inside each monomer, while the substrate binding pocket was observed within the oligomerization interfaces. The present structure is in a closed configuration, judging by the position of the lid, suggesting that the intermediate is one of the covalent adducts. The proximity of the active site to the dimerization and oligomerization interfaces, allows the dimer to sense structural changes once the benzonitrile was bound, and translated to the rest of the filament, stabilizing the helical structure.


Assuntos
Aminoidrolases , Microscopia Crioeletrônica , Nitrilas , Multimerização Proteica , Rhodococcus , Aminoidrolases/química , Aminoidrolases/metabolismo , Aminoidrolases/ultraestrutura , Microscopia Crioeletrônica/métodos , Rhodococcus/enzimologia , Nitrilas/química , Nitrilas/metabolismo , Especificidade por Substrato , Modelos Moleculares , Domínio Catalítico , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/ultraestrutura , Catálise
20.
BMC Microbiol ; 24(1): 107, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38561651

RESUMO

BACKGROUND: Belonging to the Actinobacteria phylum, members of the Rhodococcus genus thrive in soil, water, and even intracellularly. While most species are non-pathogenic, several cause respiratory disease in animals and, more rarely, in humans. Over 100 phages that infect Rhodococcus species have been isolated but despite their importance for Rhodococcus ecology and biotechnology applications, little is known regarding the molecular genetic interactions between phage and host during infection. To address this need, we report RNA-Seq analysis of a novel Rhodococcus erythopolis phage, WC1, analyzing both the phage and host transcriptome at various stages throughout the infection process. RESULTS: By five minutes post-infection WC1 showed upregulation of a CAS-4 family exonuclease, putative immunity repressor, an anti-restriction protein, while the host showed strong upregulation of DNA replication, SOS repair, and ribosomal protein genes. By 30 min post-infection, WC1 DNA synthesis genes were strongly upregulated while the host showed increased expression of transcriptional and translational machinery and downregulation of genes involved in carbon, energy, and lipid metabolism pathways. By 60 min WC1 strongly upregulated structural genes while the host showed a dramatic disruption of metal ion homeostasis. There was significant expression of both host and phage non-coding genes at all time points. While host gene expression declined over the course of infection, our results indicate that phage may exert more selective control, preserving the host's regulatory mechanisms to create an environment conducive for virion production. CONCLUSIONS: The Rhodococcus genus is well recognized for its ability to synthesize valuable compounds, particularly steroids, as well as its capacity to degrade a wide range of harmful environmental pollutants. A detailed understanding of these phage-host interactions and gene expression is not only essential for understanding the ecology of this important genus, but will also facilitate development of phage-mediated strategies for bioremediation as well as biocontrol in industrial processes and biomedical applications. Given the current lack of detailed global gene expression studies on any Rhodococcus species, our study addresses a pressing need to identify tools and genes, such as F6 and rpf, that can enhance the capacity of Rhodococcus species for bioremediation, biosynthesis and pathogen control.


Assuntos
Bacteriófagos , Rhodococcus , Humanos , Bacteriófagos/genética , Rhodococcus/genética , Rhodococcus/metabolismo , Transcriptoma , Replicação do DNA
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