RESUMEN
The genus Serratia harbors opportunistic pathogenic species, among which Serratia marcescens is pathogenic for honeybees although little studied. Recently, virulent strains of S. marcescens colonizing the Varroa destructor mite's mouth were found vectored into the honeybee body, leading to septicemia and death. Serratia also occurs as an opportunistic pathogen in the honeybee's gut with a low absolute abundance. The Serratia population seems controlled by the host immune system, but its presence may represent a hidden threat, ready to arise when honeybees are weakened by biotic and abiotic stressors. To shed light on the Serratia pathogen, this research aims at studying Serratia's development dynamics in the honeybee body and its interactions with the co-occurring fungal pathogen Vairimorpha ceranae. Firstly, the degree of pathogenicity and the ability to permeate the gut epithelial barrier of three Serratia strains, isolated from honeybees and belonging to different species (S. marcescens, Serratia liquefaciens, and Serratia nematodiphila), were assessed by artificial inoculation of newborn honeybees with different Serratia doses (104, 106, and 108 cells/mL). The absolute abundance of Serratia in the gut and in the hemocoel was assessed in qPCR with primers targeting the luxS gene. Moreover, the absolute abundance of Serratia was assessed in the gut of honeybees infected with V. ceranae at different development stages and supplied with beneficial microorganisms and fumagillin. Our results showed that all tested Serratia strains could pass through the gut epithelial barrier and proliferate in the hemocoel, with S. marcescens being the most pathogenic. Moreover, under cage conditions, Serratia better proliferates when a V. ceranae infection is co-occurring, with a positive and significant correlation. Finally, fumagillin and some of the tested beneficial microorganisms could control both Serratia and Vairimorpha development. Our findings suggest a correlation between the two pathogens under laboratory conditions, a co-occurring infection that should be taken into consideration by researches when testing antimicrobial compounds active against V. ceranae, and the related honeybees survival rate. Moreover, our findings suggest a positive control of Serratia by the environmental microorganism Apilactobacillus kunkeei in a in vivo model, confirming the potential of this specie as beneficial bacteria for honeybees.
Asunto(s)
Nosema , Serratia , Animales , Abejas/microbiología , Serratia/patogenicidad , Serratia/genética , Serratia/crecimiento & desarrollo , Nosema/patogenicidad , Nosema/crecimiento & desarrollo , Nosema/fisiología , Nosema/genética , Serratia marcescens/patogenicidad , Serratia marcescens/crecimiento & desarrollo , Serratia marcescens/genética , Tracto Gastrointestinal/microbiología , Infecciones por Serratia/microbiología , Ciclohexanos/farmacología , Serratia liquefaciens/crecimiento & desarrollo , Serratia liquefaciens/genética , Ácidos Grasos Insaturados , SesquiterpenosRESUMEN
Pyrene and chromium (Cr(VI)) are persistent pollutants and cause serious environmental problems because they are toxic to organisms and difficult to remediate. The toxicity of pyrene and Cr(VI) to three crops (cotton, soybean and maize) was confirmed by the significant decrease in root and shoot biomass during growth in pyrene/Cr(VI) contaminated hydroponic solution. Two bacterial strains capable of simultaneous pyrene biodegradation and Cr(VI) reduction were isolated and identified as Serratia sp. and Arthrobacter sp. A mixture of the isolated strains at a ratio of 1:1 was more efficient for biotreatment of pyrene and Cr(VI) than either strain alone; the mixture effectively carried out bioremediation of contaminated water in a hydroponic system mainly through pyrene biodegradation and Cr(VI) reduction. Application of these isolates shows potential for practical microbial remediation of pyrene and Cr(VI) combined water pollution.
Asunto(s)
Arthrobacter/metabolismo , Cromo/metabolismo , Pirenos/metabolismo , Serratia/metabolismo , Contaminantes Químicos del Agua/metabolismo , Arthrobacter/crecimiento & desarrollo , Biodegradación Ambiental , Técnicas de Cocultivo , Serratia/crecimiento & desarrollo , Purificación del AguaRESUMEN
The use of microorganisms that allows the recovery of critical high-tech elements such as gallium (Ga) and indium (In) has been considered an excellent eco-strategy. In this perspective, it is relevant to understand the strategies of Ga and In resistant strains to cope with these critical metals. This study aimed to explore the effect of these metals on two Ga/In resistant strains and to scrutinize the biological processes behind the oxidative stress in response to exposure to these critical metals. Two strains of Serratia fonticola, A3242 and B2A1Ga1, with high resistance to Ga and In, were submitted to metal stress and their protein profiles showed an overexpressed Superoxide Dismutase (SOD) in presence of In. Results of inhibitor-protein native gel incubations identified the overexpressed enzyme as a Fe-SOD. Both strains exhibited a huge increase of oxidative stress when exposed to indium, visible by an extreme high amount of reactive oxygen species (ROS) production. The toxicity induced by indium triggered biological mechanisms of stress control namely, the decrease in reduced glutathione/total glutathione levels and an increase in the SOD activity. The effect of gallium in cells was not so boisterous, visible only by the decrease of reduced glutathione levels. Analysis of the cellular metabolic viability revealed that each strain was affected differently by the critical metals, which could be related to the distinct metal uptakes. Strain A3242 accumulated more Ga and In in comparison to strain B2A1Ga1, and showed lower metabolic activity. Understanding the biological response of the two metal resistant strains of S. fonticola to stress induced by Ga and In will tackle the current gap of information related with bacteria-critical metals interactions.
Asunto(s)
Contaminantes Ambientales/farmacología , Galio/farmacología , Indio/farmacología , Serratia/efectos de los fármacos , Superóxido Dismutasa/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Electrónica/instrumentación , Contaminantes Ambientales/aislamiento & purificación , Contaminantes Ambientales/metabolismo , Galio/aislamiento & purificación , Galio/metabolismo , Humanos , Indio/aislamiento & purificación , Indio/metabolismo , Pruebas de Sensibilidad Microbiana , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/agonistas , Especies Reactivas de Oxígeno/metabolismo , Serratia/crecimiento & desarrollo , Serratia/metabolismo , Superóxido Dismutasa/químicaRESUMEN
Phytoremediation is an economical strategy to harvest cadmium (Cd) from contaminated soil, but the efficiency of phytoremediation was affected by many factors. This study investigated the potential of Serratia sp. K3 (K3) assisted with straw biogas residue (SBR) or leavening fertilizer (LF) on improving the Cd migration efficiency and micro-environment in soil-vetiveria zizanioides L. system. The results showed that the acid soluble Cd in soil was increased by 2.83-29.79% in treatments compared with control (CK). In addition, Cd accumulation in the roots and shoots of vetiveria zizanioides were significantly enhanced by the combination of K3 and SBR/LF. Especially, the translocation factor of Cd increased by 21.53-62.37% in groups with K3 compared with the groups without K3, correspondingly. Furthermore, SBR/LF effectively changed bacterial community structure, and improved bacterial abundance. Relative abundance of functional genes related with carbohydrate/energy/amino acid metabolism were increased in groups of SBRB/LFB rhizosphere compared with CK. These results provide insight into the change of phytoremediation efficiency and soil bacterial communities in the vetiveria zizanioides rhizosphere after inoculation. This study may provide a promising method for improving phytoremediation in Cd contaminated soil.
Asunto(s)
Cadmio/análisis , Chrysopogon/crecimiento & desarrollo , Fertilizantes/análisis , Serratia/crecimiento & desarrollo , Microbiología del Suelo , Contaminantes del Suelo/análisis , Bioacumulación , Biodegradación Ambiental , Cadmio/metabolismo , Chrysopogon/metabolismo , Estiércol/análisis , Microbiota , Rizosfera , Serratia/metabolismo , Hongos Shiitake/química , Suelo/química , Contaminantes del Suelo/metabolismo , Residuos Sólidos/análisisRESUMEN
Microbial ecosystems tightly associated with a eukaryotic host are widespread in nature. The genetic and metabolic networks of the eukaryotic hosts and the associated microbes have coevolved to form a symbiotic relationship. Both the Gram-positive Bacillus subtilis and the Gram-negative Serratia plymuthica can form biofilms on plant roots and thus can serve as a model system for the study of interspecies interactions in a host-associated ecosystem. We found that B. subtilis biofilms expand collectively and asymmetrically toward S. plymuthica, while expressing a nonribosomal antibiotic bacillaene and an extracellular protease. As a result, B. subtilis biofilms outcompeted S. plymuthica for successful colonization of the host. Strikingly, the plant host was able to enhance the efficiency of this killing by inducing bacillaene synthesis. In turn, B. subtilis biofilms increased the resistance of the plant host to pathogens. These results provide an example of how plant-bacterium symbiosis promotes the immune response of the plant host and the fitness of the associated bacteria.IMPORTANCE Our study sheds mechanistic light on how multicellular biofilm units compete to successfully colonize a eukaryote host, using B. subtilis microbial communities as our lens. The microbiota and its interactions with its host play various roles in the development and prevention of diseases. Using competing beneficial biofilms that are essential microbiota members on the plant host, we found that B. subtilis biofilms activate collective migration to capture their prey, followed by nonribosomal antibiotic synthesis. Plant hosts increase the efficiency of antibiotic production by B. subtilis biofilms, as they activate the synthesis of polyketides; therefore, our study provides evidence of a mechanism by which the host can indirectly select for beneficial microbiota members.
Asunto(s)
Antibacterianos/biosíntesis , Bacillus subtilis/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/crecimiento & desarrollo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biopelículas , Brassicaceae/microbiología , Ecosistema , Interacciones Huésped-Patógeno , Raíces de Plantas/microbiología , Polienos/metabolismo , Serratia/genética , Serratia/crecimiento & desarrollo , Serratia/fisiologíaRESUMEN
Microorganisms release a plethora of volatile secondary metabolites. Up to now, it has been widely accepted that these volatile organic compounds are produced and emitted as a final product by a single organism e.g. a bacterial cell. We questioned this commonly assumed perspective and hypothesized that in diversely colonized microbial communities, bacterial cells can passively interact by emitting precursors which non-enzymatically react to form the active final compound. This hypothesis was inspired by the discovery of the bacterial metabolite schleiferon A. This bactericidal volatile compound is formed by a non-enzymatic reaction between acetoin and 2-phenylethylamine. Both precursors are released by Staphylococcus schleiferi cells. In order to provide evidence for our hypothesis that these precursors could also be released by bacterial cells of different species, we simultaneously but separately cultivated Serratia plymuthica 4Rx13 and Staphylococcus delphini 20771 which held responsible for only one precursor necessary for schleiferon A formation, respectively. By mixing their headspace, we demonstrated that these two species were able to deliver the active principle schleiferon A. Such a joint formation of a volatile secondary metabolite by different bacterial species has not been described yet. This highlights a new aspect of interpreting multispecies interactions in microbial communities as not only direct interactions between species might determine and influence the dynamics of the community. Events outside the cell could lead to the appearance of new compounds which could possess new community shaping properties.
Asunto(s)
Antiinfecciosos/metabolismo , Antibiosis , Butanonas/metabolismo , Serratia/metabolismo , Staphylococcus/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Acetoína/metabolismo , Antiinfecciosos/química , Microbiota , Fenetilaminas/metabolismo , Percepción de Quorum , Serratia/crecimiento & desarrollo , Especificidad de la Especie , Staphylococcus/crecimiento & desarrollo , Compuestos Orgánicos Volátiles/químicaRESUMEN
Most studies of bacterial motility have examined small-scale (micrometer-centimeter) cell dispersal in monocultures. However, bacteria live in multispecies communities, where interactions with other microbes may inhibit or facilitate dispersal. Here, we demonstrate that motile bacteria in cheese rind microbiomes use physical networks created by filamentous fungi for dispersal, and that these interactions can shape microbial community structure. Serratia proteamaculans and other motile cheese rind bacteria disperse on fungal networks by swimming in the liquid layers formed on fungal hyphae. RNA-sequencing, transposon mutagenesis, and comparative genomics identify potential genetic mechanisms, including flagella-mediated motility, that control bacterial dispersal on hyphae. By manipulating fungal networks in experimental communities, we demonstrate that fungal-mediated bacterial dispersal can shift cheese rind microbiome composition by promoting the growth of motile over non-motile community members. Our single-cell to whole-community systems approach highlights the interactive dynamics of bacterial motility in multispecies microbiomes.
Asunto(s)
Queso/microbiología , ADN Bacteriano/genética , Hongos/crecimiento & desarrollo , Hifa/crecimiento & desarrollo , Interacciones Microbianas/genética , Microbiota/genética , Serratia/genética , Actinobacteria/clasificación , Actinobacteria/genética , Actinobacteria/crecimiento & desarrollo , Elementos Transponibles de ADN , Firmicutes/clasificación , Firmicutes/genética , Firmicutes/crecimiento & desarrollo , Flagelos/genética , Flagelos/ultraestructura , Hongos/ultraestructura , Secuenciación de Nucleótidos de Alto Rendimiento , Hifa/ultraestructura , Movimiento/fisiología , Mucor/crecimiento & desarrollo , Mucor/ultraestructura , Mutación , Penicillium/crecimiento & desarrollo , Penicillium/ultraestructura , Proteobacteria/clasificación , Proteobacteria/genética , Proteobacteria/crecimiento & desarrollo , Serratia/crecimiento & desarrolloRESUMEN
Plant growth promoting endophytic bacteria (PGPB) isolated from Brassica napus were inoculated in two cultivars of Helianthus tuberosus (VR and D19) growing on sand supplemented with 0.1 mM Cd or 1 mM Zn. Plant growth, concentrations of metals and thiobarbituric acid (TBA) reactive compounds were determined. Colonization of roots of H. tuberosus D19 by Pseudomonas sp. 262 was evaluated using confocal laser scanning microscopy. Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 significantly enhanced growth of H. tuberosus D19 exposed to Cd or Zn. Pseudomonas sp. 228 significantly increased Cd concentrations in roots. Serratia sp. 246, and Pseudomonas sp. 256 and 228 resulted in significantly decreased contents of TBA reactive compounds in roots of Zn exposed D19 plants. Growth improvement and decrease of metal-induced stress were more pronounced in D19 than in VR. Pseudomonas sp. 262-green fluorescent protein (GFP) colonized the root epidermis/exodermis and also inside root hairs, indicating that an endophytic interaction was established. H. tuberosus D19 inoculated with Pseudomonas sp. 228, Serratia sp. 246 and Pseudomonas sp. 262 holds promise for sustainable biomass production in combination with phytoremediation on Cd and Zn contaminated soils.
Asunto(s)
Cadmio/metabolismo , Endófitos/metabolismo , Pseudomonas/metabolismo , Serratia/metabolismo , Microbiología del Suelo , Contaminantes del Suelo/metabolismo , Zinc/metabolismo , Biodegradación Ambiental , Brassica napus/microbiología , Cadmio/toxicidad , Endófitos/efectos de los fármacos , Endófitos/crecimiento & desarrollo , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Helianthus/efectos de los fármacos , Helianthus/microbiología , Microscopía Confocal , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/microbiología , Pseudomonas/efectos de los fármacos , Pseudomonas/crecimiento & desarrollo , Serratia/efectos de los fármacos , Serratia/crecimiento & desarrollo , Contaminantes del Suelo/toxicidad , Tiobarbitúricos/metabolismo , Zinc/toxicidadRESUMEN
In this study, a bioelectrochemical system (BES) was used to treat acid mine drainage (AMD) from an abandoned coal mine in the cathode chamber under aerobic condition. Activated sludge from a local wastewater treatment plant was used in the anode chamber of the BES to supply electrons to the treatment. After 7days, the pH of the cathode solution enhanced from 2.5 to 7.3. More than 99% of Al, Fe and Pb were removed, and removal rates of 93%, 91%, 89% and 69% were achieved for Cd, Zn, Mn and Co respectively with biocathode. Energy-dispersive X-ray spectroscopy (EDS) study revealed the deposition of the various types of metals on the cathode surface, and some metals were detected in the precipitates of the cathode chamber. The bacteria for AMD treatment was identified to be Serratia spp. using 16s rRNA gene amplification and sequencing. Scanning electron microscopy showed attached growth of the bacteria on the cathode. The bioelectrochemical treatment of the AMD was also compared with the biological treatment in a continuously stirred batch reactor (CSBR).
Asunto(s)
Ácidos/química , Biodegradación Ambiental , Reactores Biológicos , Técnicas Electroquímicas/métodos , Minería , Serratia/metabolismo , Aerobiosis , Técnicas Electroquímicas/instrumentación , Electrodos , Concentración de Iones de Hidrógeno , Metales Pesados/aislamiento & purificación , Microscopía Electrónica de Rastreo , ARN Ribosómico 16S/genética , Serratia/genética , Serratia/crecimiento & desarrollo , Serratia/ultraestructura , Aguas del Alcantarillado , Espectrometría por Rayos X , Aguas ResidualesRESUMEN
The ability of bacteria and fungi to communicate with each other is a remarkable aspect of the microbial world. It is recognized that volatile organic compounds (VOCs) act as communication signals, however the molecular responses by bacteria to fungal VOCs remain unknown. Here we perform transcriptomics and proteomics analyses of Serratia plymuthica PRI-2C exposed to VOCs emitted by the fungal pathogen Fusarium culmorum. We find that the bacterium responds to fungal VOCs with changes in gene and protein expression related to motility, signal transduction, energy metabolism, cell envelope biogenesis, and secondary metabolite production. Metabolomic analysis of the bacterium exposed to the fungal VOCs, gene cluster comparison, and heterologous co-expression of a terpene synthase and a methyltransferase revealed the production of the unusual terpene sodorifen in response to fungal VOCs. These results strongly suggest that VOCs are not only a metabolic waste but important compounds in the long-distance communication between fungi and bacteria.
Asunto(s)
Compuestos Bicíclicos con Puentes/metabolismo , Fusarium/química , Octanos/metabolismo , Serratia/crecimiento & desarrollo , Compuestos Orgánicos Volátiles/farmacología , Proteínas Bacterianas/genética , Metabolismo Energético/efectos de los fármacos , Proteínas Fúngicas/farmacología , Perfilación de la Expresión Génica , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Metaboloma/efectos de los fármacos , Metabolismo Secundario/efectos de los fármacos , Análisis de Secuencia de ADN/métodos , Serratia/efectos de los fármacos , Serratia/genética , Serratia/metabolismoRESUMEN
Synthetic fatliquors are useful as a fatliquoring agent, flotation agent and emulsifying agent in a wide range of industrial applications such as leather, pharmacy and farm chemicals. These fatliquors remain recalcitrant to natural biota in existing treatment plants. In the present study, the isolated microaerophilic Serratia sp. HA1 strain CSMB3 is capable of utilizing structurally different fatliquors as the sole substrate for their growth under microaerobic conditions. Degradation of vegetable fatliquors was observed from 95 to 97% in terms of lipids, with the production of lipase at 72 h. Degradation of synthetic fatliquors was observed in terms of chemical oxygen demand from 85% to a minimum of 25%. It is in the order of sulfited/sulfated fatliquors > sulfochlorinated fatliquors > chlorinated fatliquors. A thin layer chromatography chromatogram confirmed the degradation of non polar fatliquor to polar compounds. Production of the red pigment prodigiosin in synthetic fatliquors enhanced the growth of the isolate. Fourier transform infrared spectroscopy (FTIR) confirmed the bioremediation of sulfochlorinated fatliquor into lipids and fatty acids and gas chromatography-mass spectrometry (GC-MS) results confirmed that alcohols and esters are the final end products. Thus the isolated strain CSMB3 may be used in the treatment of wastewaters containing vegetable and synthetic fatliquors.
Asunto(s)
Emulsiones/metabolismo , Lípidos/química , Aerobiosis , Biodegradación Ambiental , Análisis de la Demanda Biológica de Oxígeno , Cromatografía en Capa Delgada , Cromatografía de Gases y Espectrometría de Masas , Lipasa/metabolismo , Aceites de Plantas/química , Prodigiosina/química , Serratia/crecimiento & desarrollo , Serratia/aislamiento & purificación , Serratia/metabolismo , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
This research was conducted to isolate polycyclic aromatic hydrocarbon-degrading (PAH-degrading) endophytic bacteria and investigate their potential in protecting plants against PAH contamination. Pyrene-degrading endophytic bacteria were isolated from plants grown in PAH-contaminated soil. Among these endophytic bacteria, strain PW7 (Serratia sp.) isolated from Plantago asiatica was selected to investigate the suppression of pyrene accumulation in Triticum aestivum L. In the in vitro tests, strain PW7 degraded 51.2% of the pyrene in the media within 14 days. The optimal biodegradation conditions were pH 7.0, 30 °C, and MS medium supplemented with additional glucose, maltose, sucrose, and peptones. In the in vivo tests, strain PW7 successfully colonized the roots and shoots of inoculated (E+) wheat plants, and its colonization decreased pyrene accumulation and pyrene transportation from roots to shoots. Remarkably, the concentration of pyrene in shoots decreased much more than that in roots, suggesting that strain PW7 has the potential for protecting wheat against pyrene contamination and mitigating the threat of pyrene to human health via food consumption.
Asunto(s)
Endófitos/metabolismo , Pirenos/análisis , Serratia/metabolismo , Contaminantes del Suelo/análisis , Triticum/metabolismo , Biodegradación Ambiental , Endófitos/crecimiento & desarrollo , Humanos , Modelos Teóricos , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiología , Pirenos/metabolismo , Serratia/crecimiento & desarrollo , Contaminantes del Suelo/metabolismo , Simbiosis , Triticum/microbiologíaRESUMEN
Recovery of neodymium from liquid metallic wastes and scrap leachates is a crucial step for its recycling, which can take place through the immobilized biofilms of Serratia sp. N14. These biofilms are produced in a fermentor vessel with a turnaround time of 10-14 days, which is unacceptable from an economic point of view for an industrial process. This study proposes the construction and evaluation of a modular system, whereby a biofilm-forming chamber is inserted into the continuous biomass outflow of the main chemostat vessel, for an alternative semi-continuous and economic production of biofilm. The activity of the biofilm from the outflow chamber was found to be the same as the one from the main chamber, which was stored in a cold room (4°C), for 9-12 months, depending on a 24â h nucleation step.Moreover, the ability of the biofilm to function in the presence of a leaching agent (aqua regia) or in acidic conditions was also evaluated. The biofilm of the main chamber can remain active even at 50% neutralized aqua regia (pH 3.0), while at acidic conditions, phosphate release of the cells is reduced to 50%. This strain proves to be very tolerant in low pH or high salt concentration solutions. The biofilm produced from the outflow of the main fermentor vessel is of acceptable activity, rather than being disposed.
Asunto(s)
Reactores Biológicos , Neodimio/metabolismo , Fosfatos/metabolismo , Serratia/metabolismo , Biopelículas , Ácido Clorhídrico , Concentración de Iones de Hidrógeno , Ácido Nítrico , Serratia/crecimiento & desarrolloRESUMEN
Some novel hydrazone derivatives 6a-o were synthesized from the key intermediate 4-Chloro-N-(2-hydrazinocarbonyl-phenyl)-benzamide 5 and characterized using IR, ¹H-NMR, 13C-NMR, mass spectroscopy and elemental analysis. The inhibitory potential against two secretory phospholipase A2 (sPLA2), three protease enzymes and eleven bacterial strains were evaluated. The results revealed that all compounds showed preferential inhibition towards hGIIA isoform of sPLA2 rather than DrG-IB with compounds 6l and 6e being the most active. The tested compounds exhibited excellent antiprotease activity against proteinase K and protease from Bacillus sp. with compound 6l being the most active against both enzymes. Furthermore, the maximum zones of inhibition against bacterial growth were exhibited by compounds; 6a, 6m, and 6o against P. aeruginosa; 6a, 6b, 6d, 6f, 6l, 6m, 6n, and 6o against Serratia; 6k against S. mutans; and compounds 6a, 6d, 6e, 6m, and 6n against E. feacalis. The docking simulations of hydrazones 6a-o with GIIA sPLA2, proteinase K and hydrazones 6a-e with glutamine-fructose-6-phosphate transaminase were performed to obtain information regarding the mechanism of action.
Asunto(s)
Antibacterianos/farmacología , Endopeptidasa K/antagonistas & inhibidores , Hidrazonas/síntesis química , Hidrazonas/farmacología , Inhibidores de Fosfolipasa A2/farmacología , Inhibidores de Proteasas/farmacología , Antibacterianos/síntesis química , Bacillus/crecimiento & desarrollo , Benzamidas/química , Enterococcus faecalis/crecimiento & desarrollo , Simulación del Acoplamiento Molecular , Inhibidores de Fosfolipasa A2/síntesis química , Inhibidores de Proteasas/síntesis química , Espectroscopía de Protones por Resonancia Magnética , Pseudomonas aeruginosa/crecimiento & desarrollo , Serratia/crecimiento & desarrollo , Streptococcus mutans/crecimiento & desarrollo , Relación Estructura-ActividadRESUMEN
Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 20 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 10 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from diverse soils, and high numbers of hypobarophiles were recovered from Arctic and Siberian permafrost soils. Isolates were identified through 16S rRNA sequencing to belong to the genera Bacillus, Carnobacterium, Clostridium, Cryobacterium, Exiguobacterium, Paenibacillus, Rhodococcus, Streptomyces, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 104 cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface, or in Earth's atmosphere up to an altitude of 34 km. Key Words: Barophile-Extremophilic microorganisms-Habitability-Mars-Special Region. Astrobiology 16, 964-976.
Asunto(s)
Bacterias/aislamiento & purificación , Medio Ambiente Extraterrestre , Marte , Presión , Microbiología del Suelo , Suelo , Simulación del Espacio , Bacterias/efectos de los fármacos , Bacterias/crecimiento & desarrollo , Recuento de Colonia Microbiana , Oxígeno/farmacología , Hielos Perennes , ARN Ribosómico 16S , Análisis de Secuencia de ARN , Serratia/efectos de los fármacos , Serratia/crecimiento & desarrollo , Serratia/aislamiento & purificación , Especificidad de la Especie , TemperaturaRESUMEN
2,3-Butanediol (2,3-BD) is a promising bulk chemical with a potentially wide range of applications e.g., in the manufacture of printing inks, perfumes, synthetic rubber, fumigants, antifreeze agents, fuel additives, foodstuffs and pharmaceuticals. Its high heating value and ability to increase the octane number of fuels make 2,3-BD a promising drop-in fuel. It can also be converted to methyl-ethyl ketone (MEK), which is considered an effective liquid fuel additive. After combination with MEK and hydrogenation reaction, 2,3-BD can be converted to octane, which is used to produce high-quality aviation fuel. Currently 2,3-BD is mainly produced on an industrial scale by chemical methods. However, microbiological production of 2,3-BD offers a less expensive and more environmentally friendly alternative to traditional synthesis. This alcohol is generated from hexoses and pentoses mainly by bacterial strains of the genera Klebsiella, Bacillus, Serratia, and Enterobacter, which can convert waste products (such as glycerol and agricultural residues) and excess biomass (such as wood hydrolysates) to 2,3-BD. Recently, a significant improvement in microbial production has been achieved by the screening of efficient natural microbial strains, the application of alternative cost-effective substrates, and the genetic improvement of microbial producers. Furthermore, Klebsiella strains, which are regarded the most efficient natural 2,3-BD producers, have been subjected to genetic modifications aiming at the removal of pathogenic factors and the development of avirulent strains that could be used for the safe production of the diol. This review summarizes existing knowledge and experience concerning various strategies for efficient and economical microbial production of 2,3-BD.
Asunto(s)
Técnicas de Cultivo Celular por Lotes/métodos , Butileno Glicoles/metabolismo , Hexosas/metabolismo , Ingeniería Metabólica/métodos , Pentosas/metabolismo , Bacillus/metabolismo , Bacillus/patogenicidad , Biodegradación Ambiental , Biomasa , Butileno Glicoles/química , Enterobacter/crecimiento & desarrollo , Enterobacter/metabolismo , Fermentación , Klebsiella/crecimiento & desarrollo , Klebsiella/metabolismo , Serratia/crecimiento & desarrollo , Serratia/metabolismo , ResiduosRESUMEN
Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced nodulation response, which was associated with a significant enhancement of host larvae mortality triggered by B. thuringiensis and a Cry toxin. This was determined by an uncontrolled proliferation of midgut bacteria, after entering the body cavity through toxin-induced epithelial lesions. Consequently, the hemolymphatic microbiota dramatically changed upon treatment with Cry1Ca toxin, showing a remarkable predominance of Serratia and Clostridium species, which switched from asymptomatic gut symbionts to hemocoelic pathogens. These experimental results demonstrate the important contribution of host enteric flora in B. thuringiensis-killing activity and provide a sound foundation for developing new insect control strategies aimed at enhancing the impact of biocontrol agents by reducing the immunocompetence of the host.
Asunto(s)
Bacillus thuringiensis/patogenicidad , Proteínas Bacterianas/biosíntesis , Endotoxinas/biosíntesis , Proteínas Hemolisinas/biosíntesis , Proteínas de Insectos/antagonistas & inhibidores , Microbiota/inmunología , Control Biológico de Vectores/métodos , Spodoptera/inmunología , Animales , Bacillus thuringiensis/crecimiento & desarrollo , Toxinas de Bacillus thuringiensis , Clostridium/crecimiento & desarrollo , Clostridium/patogenicidad , Productos Agrícolas/parasitología , Regulación de la Expresión Génica , Hemocitos/inmunología , Hemocitos/microbiología , Inmunidad Innata , Terapia de Inmunosupresión , Proteínas de Insectos/genética , Proteínas de Insectos/inmunología , Intestinos/inmunología , Intestinos/microbiología , Larva/genética , Larva/inmunología , Larva/microbiología , Interferencia de ARN , ARN Bicatenario/genética , ARN Bicatenario/metabolismo , Serratia/crecimiento & desarrollo , Serratia/patogenicidad , Spodoptera/genética , Spodoptera/microbiologíaRESUMEN
Quorum sensing (QS) is a cell-to-cell communication mechanism through which microbial cells communicate and regulate their wide variety of biological activities. N-acyl homoserine lactones (AHLs) are considered to be the most important QS signaling molecules produced by several Gram-negative bacteria. The present study aimed to screen the AHLs-producing bacteria from spoiled vacuum-packaged refrigerated turbot (Scophthalmus maximus) by biosensor assays, and the profiles of AHLs produced by these bacteria were determined using reversed-phase thin-layer chromatography (RP-TLC) and gas chromatography-mass spectrometry (GC-MS). Effects of exogenous AHLs and QS inhibitor (QSI) on the phenotypes (i.e., extracellular proteolytic activity and biofilm formation) of the AHLs-producing bacteria were also evaluated. Our results demonstrated that eight out of twenty-two isolates were found to produce AHLs. Three of the AHLs-producing isolates were identified as Serratia sp., and the other five were found to belong to the family of Aeromonas. Two isolates (i.e., S. liquefaciens A2 and A. sobria B1) with higher AHLs-producing activities were selected for further studies. Mainly, RP-TLC and GC-MS analysis revealed three AHLs, i.e., 3-oxo-C6-HSL, C8-HSL and C10-HSL were produced by S. liquefaciens A2, while five AHLs, i.e., C4-HSL, C6-HSL, C8-HSL, C10-HSL, and C12-HSL, were produced by A. sobria B1. Moreover, production of AHLs in both bacterial strains were found to be density-dependent, and the AHLs activity reached a maximum level in their middle logarithmic phase and decreased in the stationary phase. The addition of exogenous AHLs and QSI decreased the specific protease activity both of the Serratia A2 and Aeromonas B1. Exogenous AHLs inhibited the biofilm formation of Serratia A2 while it enhanced the biofilm formation in Aeromonas B1. QSI inhibited the specific protease activity and biofilm formation in both bacterial strains.
Asunto(s)
4-Butirolactona/análogos & derivados , Aeromonas/metabolismo , Peces Planos/microbiología , Embalaje de Alimentos , Refrigeración , Serratia/metabolismo , 4-Butirolactona/biosíntesis , 4-Butirolactona/farmacología , Aeromonas/crecimiento & desarrollo , Aeromonas/aislamiento & purificación , Animales , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Técnicas Biosensibles/métodos , Microbiología de Alimentos , Cromatografía de Gases y Espectrometría de Masas , Fenotipo , Proteolisis/efectos de los fármacos , Percepción de Quorum/efectos de los fármacos , Alimentos Marinos/microbiología , Serratia/crecimiento & desarrollo , Serratia/aislamiento & purificación , VacioRESUMEN
There is currently an intense debate in microbial societies on whether evolution in complex communities is driven by competition or cooperation. Since Darwin, competition for scarce food resources has been considered the main ecological interaction shaping population dynamics and community structure both in vivo and in vitro. However, facilitation may be widespread across several animal and plant species. This could also be true in microbial strains growing under environmental stress. Pure and mixed strains of Serratia marcescens and Candida rugosa were grown in mineral culture media containing phenol. Growth rates were estimated as the angular coefficients computed from linearized growth curves. Fitness index was estimated as the quotient between growth rates computed for lineages grown in isolation and in mixed cultures. The growth rates were significantly higher in associated cultures than in pure cultures and fitness index was greater than 1 for both microbial species showing that the interaction between Serratia marcescens and Candida rugosa yielded more efficient phenol utilization by both lineages. This result corroborates the hypothesis that facilitation between microbial strains can increase their fitness and performance in environmental bioremediation.
Asunto(s)
Candida/fisiología , Ambiente , Serratia/fisiología , Candida/efectos de los fármacos , Candida/crecimiento & desarrollo , Fenol/farmacología , Poliuretanos/farmacología , Serratia/efectos de los fármacos , Serratia/crecimiento & desarrolloRESUMEN
Whey is a valuable co-product from cheese making that serves as a raw material for a wide range of products. Its rich nutritional content lends itself to rapid spoilage, thus it typically needs to be pasteurised and refrigerated promptly. Despite the extensive literature on milk spoilage bacteria, little is known about the spoilage bacteria of whey. The utility of carbon dioxide (CO2) to extend the shelf-life of raw milk and cottage cheese has been well established, but its application in whey preservation has not yet been explored. This study aims to characterise the microbial populations of fresh and spoiled sweet whey by culture-independent community profiling using 454 pyrosequencing of 16S rRNA gene amplicons and to determine whether carbonation is effective in inhibiting bacterial growth in sweet whey. The microbiota of raw Cheddar and Mozzarella whey was dominated by cheese starter bacteria. After pasteurisation, two out of the three samples studied became dominated by diverse environmental bacteria from various phyla, with Proteobacteria being the most dominant. Diverse microbial profiles were maintained until spoilage occurred, when the entire population was dominated by just one or two genera. Whey spoilage bacteria were found to be similar to those of milk. Pasteurised Cheddar and Mozzarella whey was spoiled by Bacillus sp. or Pseudomonas sp., and raw Mozzarella whey was spoiled by Pseudomonas sp., Serratia sp., and other members of the Enterobacteriaceae family. CO2 was effective in inhibiting bacterial growth of pasteurised Cheddar and Mozzarella whey stored at 15°C and raw Mozzarella whey stored at 4°C. The spoilage bacteria of the carbonated samples were similar to those of the non-carbonated controls.