RESUMEN
Plasma-activated seawater (PASW) presents a promising approach for marine fish preservation, yet its antimicrobial efficacy and mechanisms remain unclear. This study found that PASW exhibits superior bactericidal properties against the fish spoilage bacterium Shewanella putrefaciens compared to plasma-activated water (PAW), and increased effectiveness in preserving fish fillets. To clarify the mechanisms, a detailed investigation was conducted, including the generation of reactive oxygen/nitrogen species (ROS/RNS) and active halogen species in PASW, and their antimicrobial efficacy. Findings showed greater nitrite and hydrogen peroxide production in PASW relative to PAW, as well as the conversion of chloride/bromide ions into active species, which collectively enhanced PASW's antimicrobial activity. The synergistic action of ROS/RNS and active chlorine/bromine species in PASW promoted the generation of intracellular ROS, causing increased membrane damage, redox imbalance, and consequently higher bacterial mortality. This study enhances our understanding of PASW's antimicrobial effects and highlights its potential applications in the seafood industry.
Asunto(s)
Antibacterianos , Peces , Agua de Mar , Shewanella putrefaciens , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/metabolismo , Shewanella putrefaciens/crecimiento & desarrollo , Animales , Agua de Mar/microbiología , Agua de Mar/química , Antibacterianos/farmacología , Antibacterianos/química , Peces/microbiología , Especies Reactivas de Oxígeno/metabolismo , Conservación de Alimentos/métodos , Alimentos Marinos/microbiología , Alimentos Marinos/análisis , Gases em Plasma/farmacologíaRESUMEN
The purpose of this study was to investigate the antimicrobial effect and mechanism of slightly acidic electrolyzed water (SAEW) against Shewanella putrefaciens (S. putrefaciens) and Staphylococcus saprophytic (S. saprophyticus). The results showed that SAEW exhibited strong antimicrobial activity against tested bacteria, which was positively correlated to the available chlorine concentration (ACC) of SAEW. The mortality rate of S. putrefaciens and S. saprophyticus was up to 96% and 85%, respectively, when the ACC of SAEW was 60.0 mg/L. The results of scanning electron microscopy (SEM) showed that the cell morphology and structure were destroyed by SAEW. Besides, the results of confocal laser scanning microscopy (CLSM), leakage of DNA and protein provided evidence that SAEW induced membrane permeabilization in cells. Compared with the control, the intracellular reactive oxygen species (ROS) generated by SAEW was strengthened significantly with the increase of ACC, and the cells were injured to death accordingly.
Asunto(s)
Antibacterianos/farmacología , Electrólisis , Shewanella putrefaciens/efectos de los fármacos , Staphylococcus/efectos de los fármacos , Agua/farmacología , Antioxidantes/farmacología , Proteínas Bacterianas/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , ADN Bacteriano/metabolismo , Potenciales de la Membrana/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Modelos Biológicos , Especies Reactivas de Oxígeno/metabolismo , Shewanella putrefaciens/ultraestructura , Staphylococcus/ultraestructuraRESUMEN
The starch/polyvinyl alcohol (ST/PVA) films incorporated with cinnamaldehyde (CIN) and microfibrillated cellulose (MFC) were developed. The effect of MFC content on the films' properties was studied. The SEM results showed that MFC promoted compatibility among starch, PVA and CIN. With increased content of MFC, the strength of the films was improved and their flexibility reduced, the films' crystallinity degree and hydrophobicity were improved. The oxygen and water vapor permeability of the films both reduced first and then increased as a whole. The release of CIN from films into the food stimulant (10% ethanol) could be controlled by MFC. When MFC content was between 1% and 7.5%, it decelerated the release of CIN but high MFC content exceeded 10% promoted the release of CIN. It revealed that films containing CIN could inhibit growth of S. putrefaciens. It showed a good prospect of using MFC to develop controlled release active ST/PVA films.
Asunto(s)
Acroleína/análogos & derivados , Antiinfecciosos/farmacología , Celulosa/química , Alcohol Polivinílico/química , Almidón/química , Acroleína/química , Acroleína/farmacología , Antiinfecciosos/química , Preparaciones de Acción Retardada , Interacciones Hidrofóbicas e Hidrofílicas , Microscopía Electrónica de Rastreo/métodos , Permeabilidad , Shewanella putrefaciens/efectos de los fármacos , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Vapor , Resistencia a la Tracción , Difracción de Rayos X/métodosRESUMEN
A novel method of thermoultrasound-assisted plasma functionalized buffer (PFB) for decontaminating grass carp was evaluated using the Box-Behnken design (BBD) with processing variables including PFB generating voltage (PV), ultrasound treatment time (UT) and temperature (TP). The predicted models were found to be significant (pâ¯<â¯0.05) and displayed sufficient fitness with experimental data as indicated by non-significant (pâ¯>â¯0.05) lack of fit and high coefficient of determination (R2≥0.97) values. The optimum decontamination conditions for the responses of S. putrefaciens and S. Typhimurium were PV of 66â¯V, UT of 14.90â¯min and TP of 60â¯â, achieving reductions of 4.40 and 3.97 log CFU/g, respectively, with a desirability of 0.998. Among the variables, temperature presented higher significance for inactivating bacteria and the production of volatile basic nitrogen and lipid peroxidation under the optimized conditions were within the limits of freshness for grass carp. Additionally, the effects of PFB and the optimized thermoultrasound-assisted PFB decontamination were mild on the microstructure of grass carp with slight ruptures and loose myofibril structures, indicating the potential of thermoultrasound-assisted PFB for seafood products decontamination with reduced processing time.
Asunto(s)
Carpas/microbiología , Gases em Plasma/química , Gases em Plasma/farmacología , Salmonella typhimurium/efectos de los fármacos , Shewanella putrefaciens/efectos de los fármacos , Temperatura , Ondas Ultrasónicas , Animales , Tampones (Química) , Microbiología de Alimentos , Viabilidad Microbiana/efectos de los fármacos , Salmonella typhimurium/fisiología , Shewanella putrefaciens/fisiologíaRESUMEN
Polylactic acid (PLA) is a promising food packaging material with biocompatible, nontoxic and biodegradable. In order to reduce the deterioration of aquatic products caused by microorganisms, PLA coaxial nanofiber films with cinnamaldehyde (CMA), tea polyphenol (TP) and its composite as core materials were prepared by using coaxial electrospinning technology. Its microscopic morphology and structure were characterized separately, and its thermal stability, wettability and mechanical properties were determined. The antibacterial activity and antibacterial mechanism of nanofiber films were studied with Shewanella putrefaciens (S. putrefaciens) which is the dominant spoilage of aquatic products as the target of action. The results show that the CMA/TP (m/m = 2:5)-PLA coaxial nanofibers have small diameter, uniform distribution, smooth surface, no pores and fracture. At the same time, the film has strong hydrophobicity, good thermal stability and mechanical properties. Its antibacterial performance is better than that of single-core nanofiber films, which effectively destroys the cell membrane of S. putrefaciens, increases the permeability of cell membrane, and interferes with the synthesis and expression of its protein. The coaxial nanofiber films with CMA, TP and its composite as core material can be used as a fresh-keeping material with antibacterial properties, and has potential application value in the field of food preservation.
Asunto(s)
Acroleína/análogos & derivados , Antibacterianos/síntesis química , Poliésteres/química , Polifenoles/síntesis química , Shewanella putrefaciens/efectos de los fármacos , Té/química , Acroleína/química , Antibacterianos/química , Antibacterianos/farmacología , Materiales Biocompatibles/síntesis química , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Estabilidad de Medicamentos , Microbiología de Alimentos , Embalaje de Alimentos , Calor , Interacciones Hidrofóbicas e Hidrofílicas , Nanofibras , Polifenoles/química , Polifenoles/farmacologíaRESUMEN
The demand for reduced chemical preservative usage is currently growing, and natural preservatives are being developed to protect seafood. With its excellent antibacterial properties, linalool has been utilized widely in industries. However, its antibacterial mechanisms remain poorly studied. Here, untargeted metabolomics was applied to explore the mechanism of Shewanella putrefaciens cells treated with linalool. Results showed that linalool exhibited remarkable antibacterial activity against S. putrefaciens, with 1.5 µL/mL minimum inhibitory concentration (MIC). The growth of S. putrefaciens was suppressed completely at 1/2 MIC and 1 MIC levels. Linalool treatment reduced the membrane potential (MP); caused the leakage of alkaline phosphatase (AKP); and released the DNA, RNA, and proteins of S. putrefaciens, thus destroying the cell structure and expelling the cytoplasmic content. A total of 170 differential metabolites (DMs) were screened using metabolomics analysis, among which 81 species were upregulated and 89 species were downregulated after linalool treatment. These DMs are closely related to the tricarboxylic acid (TCA) cycle, glycolysis, amino acid metabolism, pantothenate and CoA biosynthesis, aminoacyl-tRNA biosynthesis, and glycerophospholipid metabolism. In addition, linalool substantially affected the activity of key enzymes, such as succinate dehydrogenase (SDH), pyruvate kinase (PK), ATPase, and respiratory chain dehydrogenase. The results provided some insights into the antibacterial mechanism of linalool against S. putrefaciens and are important for the development and application of linalool in seafood preservation.
Asunto(s)
Monoterpenos Acíclicos/farmacología , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Metaboloma/efectos de los fármacos , Shewanella putrefaciens/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/metabolismo , Infecciones por Bacterias Gramnegativas/microbiología , Insecticidas/farmacología , Shewanella putrefaciens/crecimiento & desarrollo , Shewanella putrefaciens/metabolismoRESUMEN
BACKGROUND: Biofilms can form in many industries, one of them is the food industry. The formation of biofilms in this industry could cause immense economic losses and endanger public health. Biofilms formation is mainly triggered by quorum sensing. Therefore, inhibition of quorum sensing could be an innovative approach to inhibit the formation of biofilms. One way to inhibit quorum sensing is by using anti-quorum sensing compounds. Actinomycetes are a group of bacteria that is acknowledged to produce these compounds. RESULTS: There were eight crude extracts of Actinomycetes isolates that showed promising anti-quorum sensing activity against Chromobacterium violaceum. The concentration of the crude extracts was 20 mg/mL. All the crude extracts showed no antibacterial activity against food spoilage bacteria, except for crude extracts of isolate 18 PM that showed antibacterial activity against Bacillus subtilis. They also showed various antibiofilm activity, both inhibition and destruction. The highest inhibition and destruction activity sequentially was done by crude extracts of isolate 12 AC with 89.60% against Bacillus cereus and crude extracts of isolate SW03 with 93.06% against Shewanella putrefaciens. CONCLUSIONS: Actinomycetes isolates that isolated from different regions in Indonesia can be used as potential candidates to overcome biofilms formed by food spoilage bacteria using their ability to produce anti-quorum sensing compounds.
Asunto(s)
Actinobacteria/metabolismo , Bacterias/crecimiento & desarrollo , Factores Biológicos/farmacología , Chromobacterium/fisiología , Percepción de Quorum/efectos de los fármacos , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Bacillus cereus/efectos de los fármacos , Bacillus cereus/crecimiento & desarrollo , Bacillus subtilis/efectos de los fármacos , Bacillus subtilis/crecimiento & desarrollo , Bacterias/efectos de los fármacos , Biopelículas/efectos de los fármacos , Factores Biológicos/aislamiento & purificación , Chromobacterium/efectos de los fármacos , Chromobacterium/crecimiento & desarrollo , Microbiología de Alimentos , Indonesia , Viabilidad Microbiana/efectos de los fármacos , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/crecimiento & desarrolloRESUMEN
AIMS: The purpose of this study was to investigate the regulatory mechanism of ε-PL on Shewanella putrefaciens. METHODS AND RESULTS: Proteomics analysis of inhibitory effect of ε-PL against S. putrefaciens was performed by label-free quantitative assay based on high-resolution mass spectrometry (MS). Quantification of 2206 proteins was obtained with high confidence, and a total of 36 differentially expressed proteins (DEPs), with 10 and 26 proteins showing upregulation and downregulation, respectively, were identified. Upon Go functional enrichment, 11, 5 and 8 specific Go terms in biological processes, molecular functions and cellular components were identified, respectively. Six KEGG pathways, including 'ribosome', were significantly enriched. Among the ribosome pathway, there were seven DEPs and all of them were distributed on large and small subunits of ribosome. CONCLUSIONS: The significant downregulation of proteins, large subunits of ribosomal proteins RP-L18, L30 and L27, small subunits ribosomal proteins S16 and S20, and RNA polymerase ß' subunit protein rpoC were the critical action sites of ε-PL to inhibit S. putrefaciens growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Shewanella putrefaciens is one of the representative fish-spoilage bacteria regardless of fish type, and poses significant problems for the fish brewery. A better understanding of the antibacterial mechanism of ε-PL on S. putrefaciens could make important contributions to development of biological control strategies of these economically important pathogens.
Asunto(s)
Lisina/farmacología , Shewanella putrefaciens , Animales , Peces , Contaminación de Alimentos , Microbiología de Alimentos , Espectrometría de Masas , Proteómica , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/genéticaRESUMEN
Bacteria release membrane vesicles into the extracellular environment but which activity is unclear. We investigated the applications of extracellular vesicles (EVs) isolated from probiotic Lactobacillus plantarum to protect tuna fish against spoilage and quality loss in this study. A significant difference was found in EVs size obtained from L. plantarum after 8, 24, and 48 hr incubation. The L. plantarum-derived EVs were collected and used to confirm the anti-bacterial activity versus Shewanella putrefaciens. Finally, the tuna fish was stored at 4 °C for 5 days after coating with EVs or sodium erythorbate, and the quality indexes were assayed. Results indicated that EVs markedly inhibited oxidation reaction, total volatile base nitrogen (TVBN), peroxide value (PV), malondialdehyde (MDA), and bacteria levels. These results finding out that EVs from L. plantarum may have potential for application in food storage technology. Overall, we indicated this new material may be developed as an anti-bacterial agent for prolonging the shelf life of tuna fish.
Asunto(s)
Antibacterianos/farmacología , Vesículas Extracelulares , Productos Pesqueros/microbiología , Microbiología de Alimentos/métodos , Lactobacillus plantarum/citología , Animales , Antibacterianos/química , Almacenamiento de Alimentos , Malondialdehído/metabolismo , Oxidación-Reducción , Probióticos , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/crecimiento & desarrollo , Atún/microbiologíaRESUMEN
Trivalent organoarsenicals such as methylarsenite (MAs(III)) are considerably more toxic than inorganic arsenate (As(V)) or arsenite (As(III)). In microbial communities MAs(III) exhibits significant antimicrobial activity. Although MAs(III) and other organoarsenicals contribute to the global arsenic biogeocycle, how they exert antibiotic-like properties is largely unknown. To identify possible targets of MAs(III), a genomic library of the gram-negative bacterium, Shewanella putrefaciens 200, was expressed in Escherichia coli with selection for MAs(III) resistance. One clone contained the S. putrefaciens murA gene (SpmurA), which catalyzes the first committed step in peptidoglycan biosynthesis. Overexpression of SpmurA conferred MAs(III) resistance to E. coli. Purified SpMurA was inhibited by MAs(III), phenylarsenite (PhAs(III)) or the phosphonate antibiotic fosfomycin but not by inorganic As(III). Fosfomycin inhibits MurA by binding to a conserved residue that corresponds to Cys117 in SpMurA. A C117D mutant was resistant to fosfomycin but remained sensitive to MAs(III), indicating that the two compounds have different mechanisms of action. New inhibitors of peptidoglycan biosynthesis are highly sought after as antimicrobial drugs, and organoarsenicals represent a new area for the development of novel compounds for combating the threat of antibiotic resistance.
Asunto(s)
Transferasas Alquil y Aril/antagonistas & inhibidores , Farmacorresistencia Bacteriana/efectos de los fármacos , Compuestos Organometálicos/farmacología , Peptidoglicano/biosíntesis , Shewanella putrefaciens/efectos de los fármacos , Transferasas Alquil y Aril/genética , Farmacorresistencia Bacteriana/genética , Escherichia coli/genética , Peptidoglicano/metabolismo , Shewanella putrefaciens/genéticaRESUMEN
Flavonoids from Sedum aizoon L. (FSAL) possess prominent antibacterial activity against Shewanella putrefaciens isolated from sea food. In the current study, the involved molecular mechanisms were investigated using transcriptome analyses combined with bioinformatics analysis in vitro for the first time. Results showed that treatment of FSAL (1.0 MIC) damaged the permeability and integrity of cell membrane and induced 721 differentially expressed genes (DEGs) in tested bacteria at transcriptional levels, including 107 DEGs were up-regulated and 614 DEGs were down-regulated. In addition, the RNA-Seq analysis revealed that the majority of DEGs mainly involved in pathways of lipopolysaccharide biosynthesis, glycerophospholipid metabolism, biosynthesis of amino acids, purine metabolism, ABC transporters and response to stimulus. In summary, the integrated results indicated that the intervention of FSAL induced destruction of cell wall and membrane, disorder of the metabolic process and redox balance, and damage of nucleic acids in S. putrefaciens, at last resulted in the death of cells. This study provided new insights into the anti- S. putrefaciens molecular mechanism underlying the treatment of FSAL, which may be served as the basis guide for identifying potential antimicrobial targets and application of FSAL in food safety.
Asunto(s)
Antibacterianos/farmacología , Flavonoides/farmacología , Perfilación de la Expresión Génica , Sedum/química , Shewanella putrefaciens/efectos de los fármacos , Membrana Celular/efectos de los fármacos , Reparación del ADN , Replicación del ADN , Biblioteca de Genes , Redes y Vías Metabólicas , Extractos Vegetales/farmacología , Especies Reactivas de Oxígeno/metabolismo , Alimentos Marinos/análisis , Alimentos Marinos/microbiología , Análisis de Secuencia de ARN , Shewanella putrefaciens/genética , Shewanella putrefaciens/metabolismoRESUMEN
ε-Polylysine (ε-PL) was studied for the growth inhibition of Shewanella putrefaciens (S. putrefaciens). The minimal inhibitory concentration (MIC) of ε-PL against S. putrefaciens was measured by the broth dilution method, while the membrane permeability and metabolism of S. putrefaciens were assessed after ε-PL treatment. Additionally, growth curves, the content of alkaline phosphatase (AKP), the electrical conductivity (EC), the UV absorbance and scanning electron microscope (SEM) data were used to study cellular morphology. The impact of ε-PL on cell metabolism was also investigated by different methods, such as enzyme activity (peroxidase [POD], catalase [CAT], succinodehydrogenase [SDH] and malic dehydrogenase [MDH]) and cell metabolic activity. The results showed that the MIC of ε-PL against S. putrefaciens was 1.0 mg/mL. When S. putrefaciens was treated with ε-PL, the growth of the bacteria was inhibited and the AKP content, electrical conductivity and UV absorbance were increased, which demonstrated that ε-PL could damage the cell structure. The enzyme activities of POD, CAT, SDH, and MDH in the bacterial solution with ε-PL were decreased compared to those in the ordinary bacterial solution. As the concentration of ε-PL was increased, the enzyme activity decreased further. The respiratory activity of S. putrefaciens was also inhibited by ε-PL. The results suggest that ε-PL acts on the cell membrane of S. putrefaciens, thereby increasing membrane permeability and inhibiting enzyme activity in relation to respiratory metabolism and cell metabolism. This leads to inhibition of cell growth, and eventually cell death.
Asunto(s)
Antibacterianos/farmacología , Membrana Celular/efectos de los fármacos , Polilisina/farmacología , Shewanella putrefaciens/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana/efectos de los fármacos , Modelos Moleculares , Shewanella putrefaciens/ultraestructuraRESUMEN
BACKGROUND: This study investigated the effect of chitosan coating enriched with extracted egg yolk antibodies on microbial and sensory quality of rainbow trout fillet during refrigeration (4 ± 1 °C). Firstly, bacterial antigen suspensions (total psychrophilic bacteria, Pseudomonas fluorescens and Shewanella putrefaciens) were injected into the breast muscles of chickens. Eggs of immunized chickens were then collected to isolate immunoglobulin from egg yolks (IgY). Fresh fish fillets were coated by chitosan solution containing different types of IgY separately, at two concentrations (60 and 90 mg mL-1 ), refrigerated for 16 days and analysed for total viable count, psychrotrophic, Pseudomonas spp., P. fluorescens and S. putrefaciens count as well as sensorial properties. RESULTS: The tested microbial values increased in all samples during the storage period; however, CH + IgY treated samples could significantly retard microbial growth compared to control. The shelf life of CH + IgY-P samples was extended for about 4 days, while it was extended for about 8 days in CH + IgY-S and CH + IgY-T samples, when they were compared to control (p < 0.05). Higher scores for sensory attributes were also observed in CH + IgY treated samples, especially in CH + IgY-S samples until the end of storage period. CONCLUSIONS: Accordingly, use of chitosan coating containing IgY increases the microbial and sensory quality of fish flesh at 4 °C. Therefore, given the consumer interest in natural additives, chitosan coating containing IgY can be a promising candidate. © 2018 Society of Chemical Industry.
Asunto(s)
Quitosano/química , Yema de Huevo/inmunología , Productos Pesqueros/análisis , Conservación de Alimentos/métodos , Inmunoglobulinas/farmacología , Animales , Pollos , Yema de Huevo/química , Productos Pesqueros/microbiología , Humanos , Inmunoglobulinas/química , Inmunoglobulinas/inmunología , Inmunoglobulinas/aislamiento & purificación , Oncorhynchus mykiss/microbiología , Pseudomonas fluorescens/efectos de los fármacos , Pseudomonas fluorescens/crecimiento & desarrollo , Refrigeración , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/crecimiento & desarrollo , GustoRESUMEN
Unusual persistent natural mortality occurred in a floating in-pond raceway system intensively stocked with channel and hybrid catfish beginning in early November 2016 up until March 2017. The temperature during the period of outbreak ranged from 7.2 to 23.7°C. Gross examination of freshly dead and moribund fish revealed pale gills, slight abdominal distension and swollen inflamed vents. Comprehensive necropsy of 20 fish demonstrated vast amounts of bloody ascitic fluid in the coelomic cavity, visceral congestion, splenomegaly and pale friable livers but macroscopically normal kidneys, suggesting systemic bacterial infection. Bacterial cultures were initiated from skin, gills and major internal organs. Following incubation, a mixture of three bacterial colony phenotypes was observed on agar plates. Presumptive biochemical characterization of the isolates followed by 16S-rRNA sequence analysis resulted in the identification of Aeromonas veronii, Streptococcus parauberis and Shewanella putrefaciens. Channel catfish juveniles were experimentally infected with the recovered isolates to fulfil Koch's postulates. Moreover, an antibiogram was used to evaluate the susceptibility of the isolates to antimicrobial drugs approved for use in aquaculture. Aquaflor was used successfully for treatment. Here, we report bacterial coinfection lead by A. veronii and the first identification of S. parauberis and S. putrefaciens from cultured catfish in North America.
Asunto(s)
Bacterias/aislamiento & purificación , Coinfección/microbiología , Enfermedades de los Peces/microbiología , Infecciones por Bacterias Gramnegativas/veterinaria , Infecciones por Bacterias Grampositivas/veterinaria , Ictaluridae/microbiología , Estaciones del Año , Aeromonas veronii/efectos de los fármacos , Aeromonas veronii/genética , Aeromonas veronii/aislamiento & purificación , Aeromonas veronii/fisiología , Animales , Antiinfecciosos/farmacología , Acuicultura , Enfermedades de los Peces/epidemiología , Infecciones por Bacterias Gramnegativas/sangre , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Infecciones por Bacterias Gramnegativas/mortalidad , Infecciones por Bacterias Grampositivas/sangre , Infecciones por Bacterias Grampositivas/tratamiento farmacológico , Infecciones por Bacterias Grampositivas/mortalidad , América del Norte/epidemiología , Estanques/microbiología , Propofol/administración & dosificación , Propofol/farmacología , Propofol/uso terapéutico , ARN Ribosómico 16S/genética , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/genética , Shewanella putrefaciens/aislamiento & purificación , Infecciones Estreptocócicas/veterinaria , Streptococcus/efectos de los fármacos , Streptococcus/genética , Streptococcus/aislamiento & purificación , Streptococcus/fisiologíaRESUMEN
Shewanella putrefaciens biofilm formation is of great concern for the shrimp industry because it adheres easily to food and food-contact surfaces and is a source of persistent and unseen contamination that causes shrimp spoilage and economic losses to the shrimp industry. Different concentrations of an antimicrobial lipopeptide, the fermentation product of Bacillus subtilis, AMPNT-6, were tested for the ability to reduce adhesion and disrupt S. putrefaciens preformed biofilms on two different contact surfaces (shrimp shell, stainless steel sheet). AMPNT-6 displayed a marked dose- and time-dependent anti-adhesive effect>biofilm removal. 3MIC AMPNT-6 was able both to remove biofilm and prevent bacteria from forming biofilm in a 96-well polystyrene microplate used as the model surface. 2MIC AMPNT-6 prevented bacteria from adhering to the microplate surface to form biofilm for 3h and removed already existing biofilm within 24h. Secretion of extracellular polymeric substances incubated in LB broth for 24h by S. putrefaciens was minimal at 3× MIC AMPNT-6. Scanning electron microscopy showed that damage to S. putrefaciens bacteria by AMPNT-6 possibly contributed to the non-adherence to the surfaces. Disruption of the mature biofilm structure by AMPNT-6 contributed to biofilm removal. It is concluded that AMPNT-6 can be used effectively to prevent attachment and also detach S. putrefaciens biofilms from shrimp shells, stainless steel sheets and polystyrene surfaces.
Asunto(s)
Exoesqueleto/microbiología , Antibacterianos/farmacología , Bacillus subtilis/química , Biopelículas/efectos de los fármacos , Microbiología de Alimentos/métodos , Penaeidae/microbiología , Alimentos Marinos/microbiología , Shewanella putrefaciens/efectos de los fármacos , Animales , Antibacterianos/aislamiento & purificación , Adhesión Bacteriana/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Relación Dosis-Respuesta a Droga , Conservación de Alimentos/métodos , Viabilidad Microbiana/efectos de los fármacos , Microscopía Electrónica de Rastreo , Poliestirenos/química , Shewanella putrefaciens/crecimiento & desarrollo , Shewanella putrefaciens/ultraestructura , Acero Inoxidable/química , Propiedades de Superficie , Factores de TiempoRESUMEN
The capability of biofilm formation has a major impact on the industrial and biotechnological applications of Shewanella putrefaciens CN32. However, the detailed regulatory mechanisms underlying biofilm formation in this strain remain largely unknown. In the present report, we describe a three-component regulatory system which negatively regulates the biofilm formation of S. putrefaciens CN32. This system consists of a histidine kinase LrbS (Sputcn32_0303) and two cognate response regulators, including a transcription factor, LrbA (Sputcn32_0304), and a phosphodiesterase, LrbR (Sputcn32_0305). LrbS responds to the signal of the carbon source sodium lactate and subsequently activates LrbA. The activated LrbA then promotes the expression of lrbR, the gene for the other response regulator. The bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) phosphodiesterase LrbR, containing an EAL domain, decreases the concentration of intracellular c-di-GMP, thereby negatively regulating biofilm formation. In summary, the carbon source sodium lactate acts as a signal molecule that regulates biofilm formation via a three-component regulatory system (LrbS-LrbA-LrbR) in S. putrefaciens CN32.IMPORTANCE Biofilm formation is a significant capability used by some bacteria to survive in adverse environments. Numerous environmental factors can affect biofilm formation through different signal transduction pathways. Carbon sources are critical nutrients for bacterial growth, and their concentrations and types significantly influence the biomass and structure of biofilms. However, knowledge about the underlying mechanism of biofilm formation regulation by carbon source is still limited. This work elucidates a modulation pattern of biofilm formation negatively regulated by sodium lactate as a carbon source via a three-component regulatory system in S. putrefaciens CN32, which may serve as a good example for studying how the carbon sources impact biofilm development in other bacteria.
Asunto(s)
Proteínas Bacterianas/metabolismo , Biopelículas , Regulación Bacteriana de la Expresión Génica , Histidina Quinasa/metabolismo , Hidrolasas Diéster Fosfóricas/metabolismo , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/fisiología , Lactato de Sodio/farmacología , Factores de Transcripción/metabolismo , Proteínas Bacterianas/genética , Biopelículas/efectos de los fármacos , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Histidina Quinasa/genética , Hidrolasas Diéster Fosfóricas/genética , Shewanella putrefaciens/genética , Factores de Transcripción/genéticaRESUMEN
Zinc oxide (ZnO) films were prepared on aluminum substrate by a hydrothermal method to investigate the effect of their surface characteristics, including morphology and hydrophobicity, on the corresponding antibiofilm performance. The surface characteristics of the prepared ZnO films were examined by a comprehensive range of methodologies, suggesting that films of distinctive surface morphologies were successfully formed. Subsequently, their antibiofilm activities, using Shewanella putrefaciens as a model bacterium, were assessed. Surface measurements confirmed that the ZnO films equipped with a nanoscopic needlelike surface feature are more hydrophobic than those possessing densely packed microflakes. The reduced number of live cells and presence of biofilm, confirmed by optical and electron microscopy results, suggest that the former films possess an excellent antibiofilm performance. It is believed that the engineered nanoscopic needle feature might penetrate the cell membrane when they are in contact, allowing the effective substance of ZnO antibacterial ingredients to diffuse into the embedded bacteria. Furthermore, such surface characteristics might perturb the integrity of the cell membrane causing the intracellular substance is leaked from the cells. As such, the combinatorial effects of nanoscopic feature resulted in an inhibited growth of S. putrefaciens biofilm on ZnO film.
Asunto(s)
Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/fisiología , Propiedades de Superficie , Óxido de Zinc/farmacología , Microscopía , NanoestructurasRESUMEN
Propolis has been used as a medicinal agent for centuries. The chemical composition of four propolis samples collected from four locations of the Sétif region, Algeria, using gas chromatography-mass spectrometry was determined. More than 20 compounds and from 30 to 35 compounds were identified in the aqueous and ethanolic extracts, respectively. Furthermore, the antimicrobial activity of the propolis extracts against two marine pathogenic bacteria was evaluated. Finally, the in vitro effects of propolis on gilthead seabream (Sparus aurata L.) leucocyte activities were measured. The bactericidal activity of ethanolic extracts was very high against Shewanella putrefaciens, average against Photobacterium damselae and very low against Vibrio harveyi. The lowest bactericidal activity was always that found for the aqueous extracts. When the viability of gilthead seabream head-kidney leucocytes was measured after 30 min' incubation with the different extracts, both the ethanolic and aqueous extracts of one of the propolis samples (from Babor) and the aqueous extract of another (from Ain-Abbassa) provoked a significant decrease in cell viability when used at concentrations of 100 and 200 µg ml-1. Furthermore, significant inhibitory effects were recorded on leucocyte respiratory burst activity when isolated leucocytes where preincubated with the extracts. This effect was dose-dependent in all cases except when extracts from a third propolis sample (from Boutaleb) were used. Our findings suggest that some of Algerian propolis extracts have bactericidal activity against important bacterial pathogens in seabream and significantly modulate in vitro leucocyte activities, confirming their potential as a source of new natural biocides and/or immunomodulators in aquaculture practice.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Inmunidad Innata/efectos de los fármacos , Photobacterium/efectos de los fármacos , Própolis/farmacología , Dorada/inmunología , Shewanella putrefaciens/efectos de los fármacos , Vibrio/efectos de los fármacos , Adyuvantes Inmunológicos/química , Argelia , Animales , Cromatografía de Gases y Espectrometría de Masas/veterinaria , Leucocitos/efectos de los fármacos , Própolis/químicaRESUMEN
Cultures of Shewanella putrefaciens grown in medium containing 10mM 1,4-diamino-2-butanone (DBO) as an inhibitor of ornithine decarboxylase and 10mM 1,5-diaminopentane (cadaverine) showed the simultaneous biosynthesis of the macrocyclic dihydroxamic acids: putrebactin (pbH2), avaroferrin (avH2) and bisucaberin (bsH2). The level of DBO did not completely repress the production of endogenous 1,4-diaminobutane (putrescine) as the native diamine substrate of pbH2. The relative concentration of pbH2:avH2:bsH2 was 1:2:1, which correlated with the substrate selection of putrescine:cadaverine in a ratio of 1:1. The macrocycles were characterised using LC-MS as free ligands and as 1:1 complexes with Fe(III) of the form [Fe(pb)]+, [Fe(av)]+ or [Fe(bs)]+, with labile ancillary ligands in six-coordinate complexes displaced during ESI-MS acquisition; or with Mo(VI) of the form [Mo(O)2(pb)], [Mo(O)2(av)] or [Mo(O)2(bs)]. Chromium(V) complexes of the form [CrO(pb)]+ were detected from solutions of Cr(VI) and pbH2 in DMF using X-band EPR spectroscopy. Supplementation of S. putrefaciens medium with DBO and 1,3-diaminopropane, 1,6-diaminohexane or 1,4-diamino-2(Z)-butene (Z-DBE) resulted only in the biosynthesis of pbH2. The work has identified a native system for the simultaneous biosynthesis of a suite of three macrocyclic dihydroxamic acid siderophores and highlights both the utility of precursor-directed biosynthesis for expanding the structural diversity of siderophores, and the breadth of their coordination chemistry.
Asunto(s)
Cromo/química , Hierro/química , Molibdeno/química , Péptidos Cíclicos/biosíntesis , Putrescina/análogos & derivados , Shewanella putrefaciens/metabolismo , Proteínas Bacterianas/antagonistas & inhibidores , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Cadaverina/metabolismo , Complejos de Coordinación/química , Diaminas/farmacología , Espectroscopía de Resonancia por Spin del Electrón , Expresión Génica , Ácidos Hidroxámicos/antagonistas & inhibidores , Ornitina Descarboxilasa/genética , Ornitina Descarboxilasa/metabolismo , Inhibidores de la Ornitina Descarboxilasa/farmacología , Péptidos Cíclicos/antagonistas & inhibidores , Putrescina/antagonistas & inhibidores , Putrescina/biosíntesis , Putrescina/farmacología , Shewanella putrefaciens/efectos de los fármacos , Shewanella putrefaciens/genética , Succinatos/antagonistas & inhibidoresRESUMEN
The objective of the study was to elucidate the biotic and abiotic processes under dissimilatory iron reducing conditions involved in reductive dechlorination and iron reduction. DDT transformation was investigated in cultures of Shewanella putrefaciens 200 with/without α-FeOOH. A modified first-order kinetics model was developed and described DDT transformation well. Both the α-FeOOH reduction rate and the dechlorination rate of DDT were positively correlated to the biomass. Addition of α-FeOOH enhanced reductive dechlorination of DDT by favoring the cell survival and generating Fe(II) which was absorbed on the surface of bacteria and iron oxide. 92% of the absorbed Fe(II) was Na-acetate (1M) extractable. However, α-FeOOH also played a negative role of competing for electrons as reflected by the dechlorination rate of DDT was inhibited when increasing the α-FeOOH from 1 g L(-1) to 5 g L(-1). DDT was measured to be toxic to S. putrefaciens 200. The metabolites DDD, DDE and DDMU were recalcitrant to S. putrefaciens 200. The results suggested that iron oxide was not the key factor to promote the dissipation of DDX (DDT and the metabolites), whereas the one-electron reduction potential (E1) of certain organochlorines is the main factor and that the E1 higher than the threshold of the reductive driving forces of DIRB probably ensures the occur of reductive dechlorination.