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1.
Molecules ; 26(14)2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34299397

RESUMO

We followed a comparative approach to investigate how heavy vacuum gas oil (HVGO) affects the expression of genes involved in biosurfactants biosynthesis and the composition of the rhamnolipid congeners in Pseudomonas sp. AK6U. HVGO stimulated biosurfactants production as indicated by the lower surface tension (26 mN/m) and higher yield (7.8 g/L) compared to a glucose culture (49.7 mN/m, 0.305 g/L). Quantitative real-time PCR showed that the biosurfactants production genes rhlA and rhlB were strongly upregulated in the HVGO culture during the early and late exponential growth phases. To the contrary, the rhamnose biosynthesis genes algC, rmlA and rmlC were downregulated in the HVGO culture. Genes of the quorum sensing systems which regulate biosurfactants biosynthesis exhibited a hierarchical expression profile. The lasI gene was strongly upregulated (20-fold) in the HVGO culture during the early log phase, whereas both rhlI and pqsE were upregulated during the late log phase. Rhamnolipid congener analysis using high-performance liquid chromatography-mass spectrometry revealed a much higher proportion (up to 69%) of the high-molecularweight homologue Rha-Rha-C10-C10 in the HVGO culture. The results shed light on the temporal and carbon source-mediated shifts in rhamonlipids' composition and regulation of biosynthesis which can be potentially exploited to produce different rhamnolipid formulations tailored for specific applications.


Assuntos
Proteínas de Bactérias/metabolismo , Gases/farmacologia , Glicolipídeos/biossíntese , Glicosiltransferases/metabolismo , Óleos Voláteis/farmacologia , Pseudomonas/metabolismo , Percepção de Quorum , Pseudomonas/efeitos dos fármacos , Pseudomonas/crescimento & desenvolvimento , Ramnose/metabolismo , Tensoativos/farmacologia , Volatilização
2.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198771

RESUMO

This study investigated within-plant variability of the main bioactive compounds in rosemary (Rosmarinus officinalis L.). Volatile terpenes, including the enantiomeric distribution of monoterpenes, and phenols were analyzed in young and mature foliar, cortical and xylem tissues. In addition, antimicrobial activity of rosmarinic acid and selected terpenes was evaluated against two rosemary pathogens, Alternaria alternata and Pseudomonas viridiflava. Data showed that total concentration and relative contents of terpenes changed in relation to tissue source and age. Their highest total concentration was observed in the young leaves, followed by mature leaves, cortical and xylem tissues. Rosmarinic acid and carnosic acid contents did not show significant differences between leaf tissues of different ages, while young and mature samples showed variations in the content of four flavonoids. These results are useful for a more targeted harvesting of rosemary plants, in order to produce high-quality essential oils and phenolic extracts. Microbial tests showed that several terpenes and rosmarinic acid significantly inhibited the growth of typical rosemary pathogens. Overall, results on antimicrobial activity suggest the potential application of these natural compounds as biochemical markers in breeding programs aimed to select new chemotypes less susceptible to pathogen attacks, and as eco-friendly chemical alternatives to synthetic pesticides.


Assuntos
Anti-Infecciosos/farmacologia , Fenóis/farmacologia , Rosmarinus/química , Terpenos/farmacologia , Alternaria/efeitos dos fármacos , Alternaria/crescimento & desenvolvimento , Anti-Infecciosos/química , Cinamatos/farmacologia , Depsídeos/farmacologia , Cromatografia Gasosa-Espectrometria de Massas , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Especificidade de Órgãos , Fenóis/química , Pseudomonas/efeitos dos fármacos , Pseudomonas/crescimento & desenvolvimento , Rosmarinus/microbiologia , Terpenos/química
3.
NPJ Biofilms Microbiomes ; 7(1): 50, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-34140515

RESUMO

Understanding the dynamic environmental microniches of biofilms will permit us to detect, manage and exploit these communities. The components and architecture of biofilms have been interrogated in depth; however, little is known about the environmental microniches present. This is primarily because of the absence of tools with the required measurement sensitivity and resolution to detect these changes. We describe the application of ratiometric fluorescent pH-sensitive nanosensors, as a tool, to observe physiological pH changes in biofilms in real time. Nanosensors comprised two pH-sensitive fluorophores covalently encapsulated with a reference pH-insensitive fluorophore in an inert polyacrylamide nanoparticle matrix. The nanosensors were used to analyse the real-time three-dimensional pH variation for two model biofilm formers: (i) opportunistic pathogen Pseudomonas aeruginosa and (ii) oral pathogen Streptococcus mutans. The detection of sugar metabolism in real time by nanosensors provides a potential application to identify therapeutic solutions to improve oral health.


Assuntos
Biofilmes , Técnicas Biossensoriais , Concentração de Íons de Hidrogênio , Nanotecnologia , Resinas Acrílicas/química , Biofilmes/crescimento & desenvolvimento , Corantes Fluorescentes/química , Glucose/metabolismo , Nanopartículas/química , Permeabilidade , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/metabolismo , Imagem com Lapso de Tempo
4.
World J Microbiol Biotechnol ; 37(5): 89, 2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33884532

RESUMO

Coumarin is widely used in personal care products and pharmaceutical industry, which leads to the release of this compound into environment as an emerging contaminant. Here, a promising strain USTB-Z for biodegrading coumarin was successfully isolated from botanical soil and characterized as a potential novel Pseudomonas sp. based on 16S rDNA sequence analysis and orthologous average nucleotide identity tool. Initial coumarin up to 800 mg/L could be completely removed by USTB-Z within 48 h at the optimal culture conditions of pH 7.3 and 30 °C, which indicates that USTB-Z has a strong capacity in coumarin biodegradation. The biodegradation products of coumarin were further investigated using HPLC and Q-TOF LC/MS, and melilotic acid and 2,3-dihydroxyphenylpropionic acid were identified. The draft genome of strain USTB-Z was sequenced by Illumina NovaSeq, and 21 CDSs for NAD (P)-dependent oxidoreductase, 43 CDSs for hydrolase, 1 CDS for FAD-depend monooxygenase, 1 CDS for 3-hydroxycinnamic acid hydroxylase, 21 CDSs for dioxygenase, and 5 CDSs for fumarylacetoacetate (FAA) hydrolase were annotated and correlated to coumarin biodegradation. The present study provides a theoretical basis and microbial resource for further research on the coumarin biodegradation.


Assuntos
Cumarínicos/química , Pseudomonas/classificação , Pseudomonas/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Análise de Sequência de DNA/métodos , Biodegradação Ambiental , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , DNA Bacteriano/genética , DNA Ribossômico/genética , Sequenciamento de Nucleotídeos em Larga Escala , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Fenóis/isolamento & purificação , Fenilpropionatos/isolamento & purificação , Filogenia , Pseudomonas/isolamento & purificação , Pseudomonas/metabolismo , Microbiologia do Solo
5.
Arch Microbiol ; 203(6): 2863-2874, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33751172

RESUMO

This research aimed to study siderophores secreted from Pseudomonas sp. PDMZnCd2003, a Zn/Cd tolerant bacterium. The effects of Zn and/or Cd stress were examined in nutrient broth to achieve the actual environmental conditions. Acid and alkali supernatants and liquid-liquid extraction with ethyl acetate and butanol were carried out to obtain crude extracts containing different amounts of the metals. The bacterial growth, UV-visible spectra of the supernatants and siderophore production indicated that the production of siderophores tended to be linked to primary metabolites. Pyocyanin was produced in all treatments, while pyoverdine was induced by stress from the metals, especially Cd. FT-IR spectra showed C=O groups and sulfur functional groups that were involved in binding with the metals. LC-MS revealed that pyocyanin, 1-hydroxy phenazine, pyoverdine, and pyochelin were present in the crude extracts. S K-edge XANES spectra showed that the main sulfur species in the extracts were the reduced forms of sulfide, thiol, and disulfide, and their oxidation states were affected by coordination with Zn and/or Cd. In addition, Zn K-edge EXAFS spectra and Cd K-edge EXAFS spectra presented Zn-O and Cd-O as coordination in the first shell, in case the extracts contained less metal. Although the mix O/S ligands had chelation bonding with Zn and Cd in the other extracts. For the role of S groups in pyochelin binding with the metals, this was the first report. The results of these experiments could be extended to Pseudomonas that respond to metal contaminated environments.


Assuntos
Cádmio/farmacologia , Pseudomonas/metabolismo , Sideróforos/isolamento & purificação , Zinco/farmacologia , Nutrientes , Pseudomonas/efeitos dos fármacos , Pseudomonas/crescimento & desenvolvimento , Piocianina/biossíntese
6.
Science ; 371(6533): 1033-1037, 2021 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-33674490

RESUMO

Microbial production of antibiotics is common, but our understanding of their roles in the environment is limited. In this study, we explore long-standing observations that microbes increase the production of redox-active antibiotics under phosphorus limitation. The availability of phosphorus, a nutrient required by all life on Earth and essential for agriculture, can be controlled by adsorption to and release from iron minerals by means of redox cycling. Using phenazine antibiotic production by pseudomonads as a case study, we show that phenazines are regulated by phosphorus, solubilize phosphorus through reductive dissolution of iron oxides in the lab and field, and increase phosphorus-limited microbial growth. Phenazines are just one of many examples of phosphorus-regulated antibiotics. Our work suggests a widespread but previously unappreciated role for redox-active antibiotics in phosphorus acquisition and cycling.


Assuntos
Antibacterianos/biossíntese , Fenazinas/metabolismo , Fósforo/metabolismo , Pseudomonas/metabolismo , Técnicas de Cultura Celular por Lotes , Disponibilidade Biológica , Oxirredução , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento
7.
FEMS Microbiol Lett ; 368(5)2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33629723

RESUMO

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products.


Assuntos
Antibacterianos/farmacologia , Antibiose/fisiologia , Bactérias/crescimento & desenvolvimento , Lactobacillus/fisiologia , Probióticos/farmacologia , Aderência Bacteriana/fisiologia , Bacteriocinas/metabolismo , Células CACO-2 , Linhagem Celular Tumoral , Escherichia coli/crescimento & desenvolvimento , Microbiologia de Alimentos/métodos , Humanos , Listeria monocytogenes/crescimento & desenvolvimento , Pseudomonas/crescimento & desenvolvimento , Salmonella/genética , Shigella/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento
8.
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
9.
Sci Rep ; 11(1): 3188, 2021 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-33542451

RESUMO

Microbial-root associations are important to help plants cope with abiotic and biotic stressors. Managing these interactions offers an opportunity for improving the efficiency and sustainability of agricultural production. By characterizing the bacterial and archaeal community (via 16S rRNA sequencing) associated with bulk and rhizosphere soil of sixteen strawberry cultivars in two controlled field studies, we explored the relationships between the soil microbiome and plant resistance to two soil-borne fungal pathogens (Verticillium dahliae and Macrophomina phaseolina). Overall, the plants had a distinctive and genotype-dependent rhizosphere microbiome with higher abundances of known beneficial bacteria such as Pseudomonads and Rhizobium. The rhizosphere microbiome played a significant role in the resistance to the two soil-borne pathogens as shown by the differences in microbiome between high and low resistance cultivars. Resistant cultivars were characterized by higher abundances of known biocontrol microorganisms including actinobacteria (Arthrobacter, Nocardioides and Gaiella) and unclassified acidobacteria (Gp6, Gp16 and Gp4), in both pathogen trials. Additionally, cultivars that were resistant to V. dahliae had higher rhizosphere abundances of Burkholderia and cultivars resistant to M. phaseolina had higher abundances of Pseudomonas. The mechanisms involved in these beneficial plant-microbial interactions and their plasticity in different environments should be studied further for the design of low-input disease management strategies.


Assuntos
Ascomicetos/genética , Resistência à Doença , Fragaria/microbiologia , Doenças das Plantas/microbiologia , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/crescimento & desenvolvimento , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/crescimento & desenvolvimento , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/patogenicidade , Fragaria/imunologia , Metagenoma , Doenças das Plantas/imunologia , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Rhizobium/genética , Rhizobium/crescimento & desenvolvimento , Rizosfera , Microbiologia do Solo
10.
Food Microbiol ; 95: 103717, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33397630

RESUMO

The objective of this study was to compare the effect of current (10 °C for 10 h followed by 0 °C with a low fan speed) versus four alternative beef carcass chilling regimes, ranging from -6 °C to 0 °C and wind speeds between 1.5 and 6 m/s on the microbiology of beef carcasses. The temperature and relative humidity (RH) in the chillers, the carcass core and surface temperature, pH, water activity (aw) and carcass weight (drip) loss were recorded. Bacterial concentrations (total viable counts (TVC), total Enterobacteriaceae counts (TEC), Pseudomonas spp., lactic acid bacteria (LAB) and Brochothrix thermosphacta) were also monitored. Similar pH, aw and drip loss (2%) values were obtained regardless of chilling regime. For the most part, bacterial concentrations were also similar and, where statistically significant (P < 0.05) counts occurred, the reductions were low (≤1 log10 cfu/cm2). It was concluded that the current chilling regime was as effective as the tested alternatives in terms of the bacterial quality of the carcasses.


Assuntos
Brochothrix/crescimento & desenvolvimento , Enterobacteriaceae/crescimento & desenvolvimento , Conservação de Alimentos/métodos , Carne/microbiologia , Pseudomonas/crescimento & desenvolvimento , Animais , Carga Bacteriana , Brochothrix/genética , Brochothrix/isolamento & purificação , Bovinos , Temperatura Baixa , Contagem de Colônia Microbiana , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Conservação de Alimentos/instrumentação , Carne/análise , Pseudomonas/genética , Pseudomonas/isolamento & purificação
11.
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
12.
J Sci Food Agric ; 101(4): 1301-1306, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32790072

RESUMO

BACKGROUND: L-Glutaminase is considered to be an important industrial enzyme in both the pharmaceutical and food industries, especially for producing functional glutamyl compounds, such as l-theanine. Pseudomonas nitroreducens SP.001 with intracellular l-glutaminase activity has been screened previously. In the present study, three physical permeabilization methods were used to improve l-glutaminase activity. Then, the whole-cell immobilization conditions of permeabilized cells using sodium alginate as an embedding agent were optimized to enhance the enzyme's stability and reusability. The characteristics of the immobilized cells were investigated in comparison with those of permeabilized cells. RESULTS: The results obtained showed that cell permeabilization using osmotic shock with 155 g L-1 sucrose markedly improved enzyme activity. Then, an effective procedure for immobilization of permeabilized P. nitroreducens cells was established. The optimum conditions for cell immobilization were: sodium alginate 40 g L-1 , calcium chloride 30 g L-1 , cell mass 100 g L-1 and a curing time of 3 h. After successful immobilization, characterization studies revealed that the thermostability and pH resistance of l-glutaminase from immobilized cells were enhanced compared to those from permeabilized cells. Moreover, the immobilized biocatalyst could be reused up to 10 times and retained 80% of its activity. CONCLUSION: The stability and reusability of the permeabilized cells were improved through the immobilization. These findings indicated that immobilized whole-cell l-glutaminase from P. nitroreducens SP.001 possesses more potential for various industrial biotechnological applications than free cells. © 2020 Society of Chemical Industry.


Assuntos
Proteínas de Bactérias/metabolismo , Glutaminase/metabolismo , Pseudomonas/enzimologia , Alginatos/química , Proteínas de Bactérias/química , Biocatálise , Células Imobilizadas/química , Células Imobilizadas/enzimologia , Glutamatos/metabolismo , Glutaminase/química , Pseudomonas/química , Pseudomonas/crescimento & desenvolvimento
13.
J Appl Microbiol ; 131(1): 208-220, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33270328

RESUMO

AIMS: To isolate, identify and characterize phenolic acid-degrading bacteria and reduce plant growth inhibition caused by phenolic acids. METHODS AND RESULTS: A total of 11 bacterial isolates with high phthalic acid (PA)-degrading ability were obtained using mineral salt medium (MSM) medium containing PA as sole carbon source. These isolates were identified as Arthrobacter globiformis, Pseudomonas putida and Pseudomonas hunanensis by sequence analyses of the 16S rRNA gene. Among them, five Pseudomonas strains could also effectively degrade ferulic acid (FA), p-hydroxybenzoic acid (PHBA) and syringic acid (SA) in MSM solution. P. putida strain 7 and P. hunanensis strain 10 showed highly efficient degradation of PA, SA, FA and PHBA, and could reduce their inhibition of lily, watermelon, poplar and strawberry seedling growth in soils respectively. These two strains could promote plant growth in soil with phenolic acids. CONCLUSIONS: In this study, bacterial strains with highly efficient phenolic acid-degrading abilities could not only effectively reduce the autotoxicity of phenolic acids on plants but also were able to promote plant growth in soil with phenolic acids. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, Pseudomonas can promote plant growth while degrading phenolic acids. Our results provide new choices for the biological removal of autotoxins.


Assuntos
Arthrobacter/metabolismo , Hidroxibenzoatos/metabolismo , Desenvolvimento Vegetal , Pseudomonas putida/metabolismo , Pseudomonas/metabolismo , Microbiologia do Solo , Arthrobacter/genética , Arthrobacter/crescimento & desenvolvimento , Biodegradação Ambiental , Ácidos Cumáricos/metabolismo , Ácido Gálico/análogos & derivados , Ácido Gálico/metabolismo , Parabenos/metabolismo , Filogenia , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , Pseudomonas putida/genética , Pseudomonas putida/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Rizosfera , Plântula/microbiologia
14.
J Dairy Sci ; 104(2): 1251-1261, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309352

RESUMO

Food loss and waste is a major concern in the United States and globally, with dairy foods representing one of the top categories of food lost and wasted. Estimates indicate that in the United States, approximately a quarter of dairy products are lost at the production level or wasted at the retail or consumer level annually. Premature microbial spoilage of dairy products, including fluid milk, cheese, and cultured products, is a primary contributor to dairy food waste. Microbial contamination may occur at various points throughout the production and processing continuum and includes organisms such as gram-negative bacteria (e.g., Pseudomonas), gram-positive bacteria (e.g., Paenibacillus), and a wide range of fungal organisms. These organisms grow at refrigerated storage temperatures, often rapidly, and create various degradative enzymes that result in off-odors, flavors, and body defects (e.g., coagulation), rendering them inedible. Reducing premature dairy food spoilage will in turn reduce waste throughout the dairy continuum. Strategies to reduce premature spoilage include reducing raw material contamination on-farm, physically removing microbial contaminants, employing biocontrol agents to reduce outgrowth of microbial contaminants, tracking and eliminating microbial contaminants using advanced molecular microbiological techniques, and others. This review will address the primary microbial causes of premature dairy product spoilage and methods of controlling this spoilage to reduce loss and waste in dairy products.


Assuntos
Laticínios/microbiologia , Microbiologia de Alimentos/métodos , Conservação de Alimentos/métodos , Animais , Manipulação de Alimentos/métodos , Fungos/crescimento & desenvolvimento , Leite/microbiologia , Paenibacillus/crescimento & desenvolvimento , Pseudomonas/crescimento & desenvolvimento , Eliminação de Resíduos , Estados Unidos
15.
Meat Sci ; 171: 108282, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32858421

RESUMO

Pseudomonas have a faster growth rate over other bacteria in chilled meat under aerobic conditions. A non-destructive method for modelling the dynamic growth of Pseudomonas in pork stored at different temperatures using gas sensors was presented in our work. Based on selected gas sensor data, the first-order kinetic equations (Gompertz and Logistic Functions) combined with the secondary model (Square-root Function) effectively simulated Pseudomonas growth in pork at different temperatures with R2 and RMSE values of 0.71-0.97 and 0.27-0.84, respectively. Additionally, these models showed high accuracy with correlation coefficients greater than 0.90, in addition to several individual accuracy values. Furthermore, HS-SPME/GC-MS results demonstrated the presence of identified key volatiles in samples inoculated with Pseudomonas, including three amine compounds (mercaptamine, 1-octanamine and 1-heptadecanamine), phenol and indole. Our work showed that gas sensors are a rapid, easy and non-destructive method with acceptable feasibility in modelling the dynamic growth of spoilage microorganisms in meat.


Assuntos
Nariz Eletrônico , Carne de Porco/microbiologia , Pseudomonas/crescimento & desenvolvimento , Animais , Microbiologia de Alimentos/métodos , Pseudomonas/metabolismo , Suínos , Temperatura , Compostos Orgânicos Voláteis/análise
16.
Genes (Basel) ; 11(12)2020 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-33260964

RESUMO

Pseudomonas sp. strain LLC-1 (NBRC 111237) is capable of degrading lignin-derived low-molecular-weight compounds (LLCs). The genes responsible for the catabolism of LLCs were characterized in this study using whole-genome sequencing. Despite the close phylogenetic relationship with Pseudomonas putida, strain LLC-1 lacked the genes usually found in the P. putida genome, which included fer, encoding an enzyme for ferulic acid catabolism, and vdh encoding an NAD+-dependent aldehyde dehydrogenase specific for its catabolic intermediate, vanillin. Cloning and expression of the 8.5 kb locus adjacent to the van operon involved in vanillic acid catabolism revealed the bzf gene cluster, which is involved in benzoylformic acid catabolism. One of the structural genes identified, bzfC, expresses the enzyme (BzfC) having the ability to transform vanillin and syringaldehyde to corresponding acids, indicating that BzfC is a multifunctional enzyme that initiates oxidization of LLCs in strain LLC-1. Benzoylformic acid is a catabolic intermediate of (R,S)-mandelic acid in P. putida. Strain LLC-1 did not possess the genes for mandelic acid racemization and oxidation, suggesting that the function of benzoylformic acid catabolic enzymes is different from that in P. putida. Genome-wide characterization identified the bzf gene responsible for benzoylformate and vanillin catabolism in strain LLC-1, exhibiting a unique mode of dissimilation for biomass-derived aromatic compounds by this strain.


Assuntos
Genes Bacterianos , Lignina/metabolismo , Metabolismo/genética , Pseudomonas/genética , Aldeídos/metabolismo , Benzaldeídos/metabolismo , Biotransformação/genética , Ácidos Carboxílicos/metabolismo , Escherichia coli/genética , Cromatografia Gasosa-Espectrometria de Massas , Glioxilatos/metabolismo , Japão , Cetonas/metabolismo , Ácidos Mandélicos/metabolismo , Peso Molecular , Filogenia , Pseudomonas/classificação , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/metabolismo , Pseudomonas putida/genética , Ribotipagem , Microbiologia do Solo , Especificidade da Espécie , Sequenciamento Completo do Genoma
17.
J Agric Food Chem ; 68(50): 14907-14916, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-33274638

RESUMO

The combined action of biosorption and biodegradation can achieve a remarkable reduction of organic pollutants. In this study, Pseudomonas sp. SDR4 and Mortierella alpina JDR7 were selected as the representative microorganisms to investigate adsorption and degradation of polycyclic aromatic hydrocarbons (PAHs) in soil using immobilization technology and the subsequent change of the microbial community structure. The results showed that the adsorption capacity of immobilized carriers was much higher than that of dead microorganisms and that the addition of dead microorganisms did not affect the adsorption characteristics of immobilized carriers. The chemical reaction was the major factor controlling the adsorption rate of PAHs in sterilized soil (CK), nonsterilized soil (CK-1), and soil amended with dead body immobilized JDR7 and SDR4 mixed bacteria (MB-D). The growth and metabolism of Pseudomonas sp. SDR4 and M. alpina JDR7 are the main reason for enhanced PAH degradation in the soil amended with living body immobilized JDR7, SDR4 mixed bacteria (MB).


Assuntos
Bactérias/metabolismo , Mortierella/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Pseudomonas/metabolismo , Microbiologia do Solo , Solo/química , Adsorção , Bactérias/classificação , Bactérias/genética , Biodegradação Ambiental , Microbiota , Mortierella/crescimento & desenvolvimento , Hidrocarbonetos Policíclicos Aromáticos/química , Pseudomonas/crescimento & desenvolvimento
18.
Sci Rep ; 10(1): 16457, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-33020559

RESUMO

Psychrotrophic Pseudomonas species are the key spoilage bacteria of aerobically stored chilled meat. These organisms readily form biofilms on meat under refrigerated conditions leading to consumer rejection and associated economic losses. Limited information is available on the matrix composition of the biofilms formed by these bacteria. We quantified and characterized the main components of the matrix of mono-species biofilms of selected Pseudomonas fragi and Pseudomonas lundensis strains using chemical analysis and Raman spectroscopy. The biofilms were grown at 10 °C and 25 °C on nitro-cellulose membranes placed on surface sterilized beef cuts. Extra-cellular polymeric substances of the matrix were extracted in soluble and bound forms and were chemically assessed for total carbohydrates, proteins and extra-cellular DNA. Both Pseudomonas species showed a significant increase in total carbohydrates and total proteins when grown at 10 °C as compared to 25 °C. Extra-cellular DNA did not show a strong correlation with growth temperature. Raman spectra were obtained from planktonic bacteria and membrane grown biofilms at 10 °C and 25 °C. Higher levels of guanine were detected in planktonic cells as compared to biofilm cells. This study suggests that psychrotrophic Pseudomonas species may respond to cold stress by increasing extra-cellular polymer secretions.


Assuntos
Biofilmes/crescimento & desenvolvimento , Carne/microbiologia , Pseudomonas fragi/crescimento & desenvolvimento , Pseudomonas/crescimento & desenvolvimento , Animais , Bovinos , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Microbiologia de Alimentos/métodos , Pseudomonas/metabolismo , Pseudomonas fragi/metabolismo , Temperatura
19.
Enzyme Microb Technol ; 141: 109668, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33051018

RESUMO

Lactobionic acid (LBA) has been widely used in the food, pharmaceutical, and cosmetic industries. Pseudomonas taetrolens is an efficient LBA-producing bacterium. To improve the LBA-production ability of P. taetrolens, we modified the strain by genetic engineering. We performed homologous expression of the quinoprotein glucose dehydrogenase gene in P. taetrolens and measured the intracellular lactose-oxidizing activity and LBA production titer. In flask cultures at 12 h of incubation, the intracellular lactose oxidizing activity (0.159 U/g dry weight cell) and LBA production titer (77.2 g/L) of the recombinant P. taetrolens were approximately 118 % and 69 % higher than those (0.073 U/g dry weight cell and 45.8 g/L, respectively) of wild-type P. taetrolens. Using this recombinant strain as a whole-cell biocatalyst (WCB), the effects of reaction parameters, such as reaction temperature, cell density, and cell harvest time, were investigated on LBA production. Under optimized reaction conditions, the LBA production titer, yield, and productivity of WCB were 200 g/L, 95.6 %, and 16.7 g/L/h, respectively. Compared with our previous study, LBA production titer, yield, and productivity, which are key factors for industrial LBA production, were significantly improved by fermentation of wild-type P. taetrolens. Moreover, the reaction for LBA production could be performed up to seven times without a significant reduction in productivity, implying that this WCB was rather robust. Our results suggest that the utilization of whole-cell biocatalysis using recombinant P. taetrolens provides a potential solution to achieve economically feasible production of LBA.


Assuntos
Dissacarídeos/biossíntese , Pseudomonas/metabolismo , Biocatálise , Reatores Biológicos , Fermentação , Engenharia Genética , Glucose Desidrogenase/genética , Glucose Desidrogenase/metabolismo , Lactose/metabolismo , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , Temperatura , Fatores de Tempo
20.
FEMS Microbiol Lett ; 367(18)2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32897322

RESUMO

Herbicides have been extensively used globally, resulting in severe environmental pollution. Novel butachlor-degrading Pseudomonas sp. strain But2 isolated from soil can degrade butachlor regardless of the concentration and grows without a lag phase. Specific degradation was increased at 0.01-0.1 mM, and did not change significantly at higher concentrations. During degradation, 2-chloro-N-(2,6-diethylphenyl) acetamide, 2,6-diethylaniline, and 1,3-diethylbenzene were formed, which indicated that deamination occurred. Moreover, Pseudomonas sp. strains could tolerate propanil at up to 0.8 mM. The mixed bacterial culture of Pseudomonas sp. But2 and Acinetobacter baumannii DT (a propanil-degrading bacterial strain) showed highly effective biodegradation of both butachlor and propanil in liquid media and soil. For example, under treatment with the mixed culture, the half-lives of propanil and butachlor were 1 and 5 days, respectively, whereas those for the control were 3 and 15 days. The adjuvants present in herbicides reduced degradation in liquid media, but did not influence herbicide removal from the soil. The results showed that the mixed bacteria culture is a good candidate for the removal of butachlor and propanil from contaminated soils.


Assuntos
Acetanilidas/metabolismo , Acinetobacter baumannii/metabolismo , Herbicidas/metabolismo , Propanil/metabolismo , Pseudomonas/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Desaminação , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/isolamento & purificação , Microbiologia do Solo
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