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1.
Food Microbiol ; 86: 103337, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703870

RESUMO

Coenzyme Q0 (CoQ0) has demonstrated antitumor, anti-inflammatory, and anti-angiogenic activities. Cronobacter sakazakii is an opportunistic foodborne pathogen associated with high mortality in neonates. In this study, the antimicrobial activity and possible antimicrobial mechanism of CoQ0 against C. sakazakii were investigated. Moreover, the inactivation effect of CoQ0 on C. sakazakii in biofilms was also evaluated. The minimum inhibitory concentration (MIC) of CoQ0 against C. sakazakii strains ranged from 0.1 to 0.2 mg/mL. Treatment caused cell membrane dysfunction, as evidenced by cell membrane hyperpolarization, decreased intracellular ATP concentration and cell membrane integrity, and changes in cellular morphology. CoQ0 combined with mild heat treatment (45, 50, or 55 °C) decreased the number of viable non-desiccated and desiccated C. sakazakii cells in a time- and dose-dependent manner in reconstituted infant milk. Furthermore, CoQ0 showed effective inactivation activity against C. sakazakii in biofilms on stainless steel, reducing the number of viable cells and damaging the structure of the biofilm. These findings suggest that CoQ0 has a strong inactivate effect on C. sakazakii and could be used in food production environments to effectively control C. sakazakii and reduce the number of illnesses associated with it.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Cronobacter sakazakii/efeitos dos fármacos , Ubiquinona/análogos & derivados , Membrana Celular/efeitos dos fármacos , Cronobacter sakazakii/crescimento & desenvolvimento , Cronobacter sakazakii/fisiologia , Fórmulas Infantis/análise , Fórmulas Infantis/microbiologia , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Plâncton/fisiologia , Ubiquinona/farmacologia
2.
Mar Pollut Bull ; 148: 97-106, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31422308

RESUMO

This study provides the first measurement of microplastic abundance and distribution in surface waters and sediments in Tampa Bay, FL. Microplastic concentrations in discrete water samples ranged from 0.25 to 7.0 particles/L with an average of 0.94 (±0.52) particles/L. Samples taken with a 330 µm plankton net had 1.2-18.1 particles/m3 with an average of 4.5 (±2.3) particles/m3. Discrete samples were 200 times higher than net samples, suggesting substantial losses or undersampling with the net. For both discrete and plankton tow samples, there were no significant differences in concentrations between stations or regions. Intense rainfall events in the summer always preceded samples with substantially higher counts. Most (>75%) microplastics were fibers. Using an average value of 1 particle/L, Tampa Bay contains ~4 billion microplastic particles. Surface sediments had an average of 280 (±290) particles/kg, ranging from 30 to 790 particles/kg. Highest concentrations of microplastics were found in sediments close to industrial sources; lowest values in Middle and Lower Tampa Bay are consistent with shorter residence times.


Assuntos
Sedimentos Geológicos/análise , Poluentes Químicos da Água/análise , Baías/análise , Monitoramento Ambiental , Estuários , Florida , Plâncton/crescimento & desenvolvimento , Plâncton/metabolismo , Estações do Ano , Poluição Química da Água/análise
3.
PLoS One ; 14(7): e0217205, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31329599

RESUMO

Adjunctive use of antibiotics in periodontal treatment have limitations and disadvantages including bacterial resistance. Antimicrobial peptides (AMPs) are potential new agents that can combat bacterial infection. In this study, antimicrobial activity of different concentrations of conventional antibiotics minocycline (MH), doxycycline (DOX), and antimicrobial peptides LL-37, LL-31, Lactoferrin chimera (LFchimera) and Innate Defense Regulator Peptide 1018 (IDR-1018) against Aggregatibacter actinomycetemcomitans ATCC 43718 were determined using colony culturing assay. Subsequently, in vitro activity of the most effective drug and peptide combination was evaluated by checkerboard technique. Impact of the drug and peptide co-administration on biofilm at different stages, i.e., during adhesion and 1-day old biofilm was compared to each of the agents used alone. Results revealed that the killing effects of all AMPs range from 13-100%. In contrast, MH and DOX at 1 and 5 µM showed no killing activity and instead stimulated growth of bacteria. DOX has better killing activity than MH. LFchimera displayed the strongest killing amongst the peptides. Checkerboard technique revealed that combining DOX and LFchimera yielded synergism. Confocal laser scanning microscopy further showed that the combination of DOX and LFchimera caused significant reduction of bacterial adhesion and reduction of biomass, average biofilm thickness and substratum biofilm coverage of 1-day old biofilm compared to DOX and LFchimera alone. In conclusion, LFchimera alone and in combination with DOX exhibited strong antibacterial and anti-biofilm property against A. actinomycetemcomitans. The findings suggest that LFchimera should be considered for development as a new potential therapeutic agent that may be used as an adjunctive treatment for periodontitis.


Assuntos
Aggregatibacter actinomycetemcomitans/fisiologia , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Biofilmes/efeitos dos fármacos , Lactoferrina/farmacologia , Plâncton/crescimento & desenvolvimento , Antibacterianos/química , Peptídeos Catiônicos Antimicrobianos/agonistas , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/genética , Biofilmes/crescimento & desenvolvimento , Sinergismo Farmacológico , Humanos , Lactoferrina/agonistas , Lactoferrina/química , Lactoferrina/genética , Periodontite/tratamento farmacológico , Periodontite/microbiologia , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/farmacologia
4.
Molecules ; 24(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340472

RESUMO

In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25-0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5-6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5-5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Ouro/farmacologia , Nanotubos/química , Plâncton/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/química , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos da radiação , Contagem de Colônia Microbiana , Ouro/química , Hidrogéis/química , Terapia com Luz de Baixa Intensidade/métodos , Microscopia Eletrônica de Transmissão , Nanotubos/ultraestrutura , Fosfatidiletanolaminas/química , Plâncton/crescimento & desenvolvimento , Plâncton/efeitos da radiação , Poloxâmero/química , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/efeitos da radiação , Pseudomonas aeruginosa/ultraestrutura
5.
PLoS One ; 14(6): e0217869, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188854

RESUMO

Vibrio cholerae is an important human pathogen causing intestinal disease with a high incidence in developing countries. V. cholerae can switch between planktonic and biofilm lifestyles. Biofilm formation is determinant for transmission, virulence and antibiotic resistance. Due to the enhanced antibiotic resistance observed by bacterial pathogens, antimicrobial nanomaterials have been used to combat infections by stopping bacterial growth and preventing biofilm formation. In this study, the effect of the nanocomposites zeolite-embedded silver (Ag), copper (Cu), or zinc (Zn) nanoparticles (NPs) was evaluated in V. cholerae planktonic cells, and in two biofilm states: pellicle biofilm (PB), formed between air-liquid interphase, and surface-attached biofilm (SB), formed at solid-liquid interfaces. Each nanocomposite type had a distinctive antimicrobial effect altering each V. cholerae lifestyles differently. The ZEO-AgNPs nanocomposite inhibited PB formation at 4 µg/ml, and prevented SB formation and eliminated planktonic cells at 8 µg/ml. In contrast, the nanocomposites ZEO-CuNPs and ZEO-ZnNPs affect V. cholerae viability but did not completely avoid bacterial growth. At transcriptional level, depending on the nanoparticles and biofilm type, nanocomposites modified the relative expression of the vpsL, rbmA and bap1, genes involved in biofilm formation. Furthermore, the relative abundance of the outer membrane proteins OmpT, OmpU, OmpA and OmpW also differs among treatments in PB and SB. This work provides a basis for further study of the nanomaterials effect at structural, genetic and proteomic levels to understand the response mechanisms of V. cholerae against metallic nanoparticles.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Nanopartículas Metálicas/química , Nanocompostos/química , Plâncton/efeitos dos fármacos , Vibrio cholerae/efeitos dos fármacos , Antibacterianos/química , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Biofilmes/crescimento & desenvolvimento , Cobre/química , Película Dentária/efeitos dos fármacos , Película Dentária/microbiologia , Humanos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Nanocompostos/ultraestrutura , Plâncton/crescimento & desenvolvimento , Prata/química , Transcrição Genética , Vibrio cholerae/crescimento & desenvolvimento , Vibrio cholerae/ultraestrutura , Zeolitas/química , Zinco/química
6.
ISME J ; 13(9): 2196-2208, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31053831

RESUMO

Although it is widely recognized that cyanobacterial blooms have substantial influence on the plankton community in general, their correlations with the whole community of eukaryotic plankton at longer time scales remain largely unknown. Here, we investigated the temporal dynamics of eukaryotic plankton communities in two subtropical reservoirs over a 6-year period (2010-2015) following one cyanobacterial biomass cycle-the cyanobacterial bloom (middle 2010), cyanobacteria decrease (late 2010-early 2011), non-bloom (2011-2014), cyanobacteria increase, and second bloom (late 2014-2015). The eukaryotic community succession that strongly correlated with this cyanobacterial biomass cycle was divided into four periods, and each period had distinct characteristics in cyanobacterial biomass and environments in both reservoirs. Integrated co-occurrence networks of eukaryotic plankton based on the whole study period revealed that the cyanobacterial biomass had remarkably high network centralities, and the eukaryotic OTUs that had stronger correlations with the cyanobacterial biomass exhibited higher centralities. The integrated networks were also modularly responded to different eukaryotic succession periods, and therefore correlated with the cyanobacterial biomass cycle. Moreover, sub-networks based on the different eukaryotic succession periods indicated that the eukaryotic co-occurrence patterns were not constant but varied largely associating with the cyanobacterial biomass. Based on these long-term observations, our results reveal that the cyanobacterial biomass cycle created distinct niches between persistent bloom, non-bloom, decrease and increase of cyanobacteria, and therefore associated with distinct eukaryotic plankton patterns. Our results have important implications for understanding how complex aquatic plankton communities respond to cyanobacterial blooms under the changing environments.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Eucariotos/crescimento & desenvolvimento , Plâncton/crescimento & desenvolvimento , Biomassa , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Ecossistema , Eucariotos/classificação , Eucariotos/genética , Eucariotos/isolamento & purificação , Eutrofização , Filogenia , Plâncton/classificação , Plâncton/genética , Plâncton/isolamento & purificação
7.
Vet Res ; 50(1): 24, 2019 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-30971289

RESUMO

The impact of cortisol on Flavobacterium columnare biofilm formation was explored. Firstly, the dynamics of biofilm formation by one highly (HV) and one low virulent (LV) F. columnare isolate with and without the stress hormone cortisol under microfluidic flow conditions was characterized. This to confirm that F. columnare cells could form biofilm under cortisol supplementation, and to compare the temporal and structural differences between different treatment groups. One trial revealed that in both isolates cell aggregates resembling biofilms occurred within 7-h post-inoculation. Consequently, cell clusters were sloughed away, followed by a rebuilding of bacterial cell aggregates, suggestive for a high spreading capacity. While the HV isolate revealed cell aggregates formed upstream at all time-points, for the LV isolate this was only seen upon cortisol supplementation. Secondly, the transcriptional effect of genes (gldK, gldL, gldM, gldN, sprA, sprE, sprT, and porV) belonging to the Type IX secretion system involved in gliding motility was investigated in planktonic and biofilm cells of a HV and LV isolate to which no, a low (LD) or high (HD) dose of cortisol was added. Significantly lower expression of gliding genes gldK, gldL, gldM and gldN, and of protein secretion regulator porV was seen in the LV isolate planktonic cells supplemented with a HD-cortisol. The LV isolate biofilm cells treated with the HD-cortisol showed a significant upregulation of sprT, encoding mobile surface adhesion important in bacterial colonization. This is the first evidence for the co-regulatory effect of cortisol on biofilm formation and F. columnare gliding gene expression.


Assuntos
Aderência Bacteriana/genética , Biofilmes/crescimento & desenvolvimento , Flavobacterium/fisiologia , Expressão Gênica , Genes Bacterianos/fisiologia , Hidrocortisona/metabolismo , Animais , Biofilmes/efeitos dos fármacos , Carpas/microbiologia , Relação Dose-Resposta a Droga , Flavobacterium/efeitos dos fármacos , Flavobacterium/genética , Flavobacterium/patogenicidade , Hidrocortisona/administração & dosagem , Dispositivos Lab-On-A-Chip/veterinária , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Virulência
8.
Mol Ecol ; 28(5): 920-922, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30938044

RESUMO

How diverse are marine planktonic protist communities? How much seasonality do they exhibit? For a very long time, these two old and challenging questions in the field of plankton ecology could be addressed only for large-size protist species, based on cell counting under the microscope. The recent application of molecular techniques, notably massive marker-gene amplicon sequencing approaches (metabarcoding), has allowed investigating with unprecedented level of resolution the small-sized (<20 µm) planktonic eukaryotes too. An amazing diversity of these tiny organisms has been unveiled but details about their temporal dynamics remain much more elusive. In a From the Cover article in this issue of Molecular Ecology, Giner et al. (2019) introduce a new Recurrence Index (RI) to specifically look for seasonality in time-series metabarcoding data. They inspected the temporal dynamics of all operational taxonomic units (OTUs) in a rich sequence data set of pico- and nanoplanktonic eukaryotes in samples collected monthly during 10 years. Although most OTUs did not show seasonality, some abundant ones did, which explains why some averaging methods can find seasonality at the less detailed level of whole planktonic communities. Not surprisingly, the very complex small-sized eukaryotic plankton communities are composed of organisms with miscellaneous temporal dynamics.


Assuntos
Ecossistema , Plâncton/genética , RNA Ribossômico 18S/genética , Biodiversidade , Classificação , Eucariotos , Filogenia , Plâncton/crescimento & desenvolvimento
9.
Biocontrol Sci ; 24(1): 13-21, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30880309

RESUMO

Although the most common bacteria in the supragingival plaque are Gram-positive streptococci, no extensive investigations have been conducted into the susceptibility of these species to chlorhexidine and cetylpyridinium chloride. Therefore, in this study, we investigated the susceptibility of 80 streptococcal strains in planktonic or biofilm states to these two antimicrobial agents. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the planktonic streptococci were measured using the microdilution method, as were the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) measured on streptococcal biofilms formed on 96-well plates. In all species, the MIC, MBC, MBIC, and MBEC values were higher for chlorhexidine than for cetylpyridinium chloride, with sensitivity values varying according to species. For chlorhexidine, the MIC, MBC, and MBIC values showed statistically significant differences among species. However, only MBEC values showed statistically significant differences for cetylpyridinium chloride. The MIC against Streptococcus mutans and the MBC against Streptococcus salivarius were significantly lower than those against the other species. With he exception of a few species, most of the bacterium susceptibility values were higher in the biofilm state than in the planktonic state.


Assuntos
Anti-Infecciosos Locais/farmacologia , Biofilmes/efeitos dos fármacos , Cetilpiridínio/farmacologia , Clorexidina/farmacologia , Plâncton/efeitos dos fármacos , Streptococcus/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Placa Dentária/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Streptococcus/isolamento & purificação
10.
PLoS One ; 14(1): e0209823, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30640913

RESUMO

Climate change is expected to exacerbate upwelling intensity and natural acidification in Eastern Boundaries Upwelling Systems (EBUS). Conducted between January-September 2015 in a nearshore site of the northern Humboldt Current System directly exposed to year-round upwelling episodes, this study was aimed at assessing the relationship between upwelling mediated pH-changes and functional traits of the numerically dominant planktonic copepod-grazer Acartia tonsa (Copepoda). Environmental temperature, salinity, oxygen, pH, alkalinity, chlorophyll-a (Chl), copepod adult size, egg production (EP), and egg size and growth were assessed through 28 random oceanographic surveys. Agglomerative clustering and multidimensional scaling identified three main di-similitude nodes within temporal variability of abiotic and biotic variables: A) "upwelling", B) "non-upwelling", and C) "warm-acid" conditions. Nodes A and B represented typical features within the upwelling phenology, characterized by the transition from low temperature, oxygen, pH and Chl during upwelling to higher levels during non-upwelling conditions. However, well-oxygenated, saline and "warm-acid" node C seemed to be atypical for local climatology, suggesting the occurrence of a low frequency oceanographic perturbation. Multivariate (LDA and ANCOVA) analyses revealed upwelling through temperature, oxygen and pH were the main factors affecting variations in adult size and EP, and highlighted growth rates were significantly lower under node C. Likely buffering upwelling pH-reductions, phytoplankton biomass maintained copepod reproduction despite prevailing low temperature, oxygen and pH levels in the upwelling setting. Helping to better explain why this species is among the most recurrent ones in these variable yet productive upwelling areas, current findings also provide opportune cues on plankton responses under warm-acid conditions, which are expected to occur in productive EBUS as a consequence of climate perturbations.


Assuntos
Copépodes/fisiologia , El Niño Oscilação Sul/efeitos adversos , Fitoplâncton/crescimento & desenvolvimento , Animais , Biomassa , Clorofila A/análise , Mudança Climática , Copépodes/crescimento & desenvolvimento , Ecossistema , Concentração de Íons de Hidrogênio , Plâncton/crescimento & desenvolvimento , Dinâmica Populacional , Salinidade , Estações do Ano , Temperatura
11.
Environ Pollut ; 244: 314-322, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30343232

RESUMO

Silver ions are among the predominant anthropogenic introduced pollutants in aquatic systems. As silver has effects on species at all trophic levels the community composition in aquatic habitats can be changed as a result of silver stress. The response of planktonic protists to environmental stressors is particularly important as they act both as producers and consumers in complex planktonic communities. Chrysomonad flagellates are of major interest, since this group includes heterotrophic, mixotrophic and phototrophic taxa, and therefore allows analysis of silver stress in organisms with contrasting nutritional strategies independent of a potential taxonomic bias. In a series of lab experiments, we compared the response of different trophic chrysophyte strains to low (5 µg L-1), medium (10 µg L-1) and high (20 µg L-1) nominal Ag concentrations in combination with changes in temperature and light intensity (phototrophs), temperature and food concentration (heterotrophs), or a combination of the above settings (mixotrophs). All tested strains were negatively affected by silver in their growth rates. The phototrophic strains reacted strongly to silver stress, whereas light intensity and temperature had only minor effects on growth rates. For heterotrophic strains, high food concentration toned down the effect of silver, whereas temperatures outside the growth optimum had a combined stress effect. The mixotrophic strains reacted differently depending on whether their nutritional mode was dominated by heterotrophy or by phototrophy. The precise response pattern across all variables was uniquely different for every single species we tested. The present work contributes to a deeper understanding of the effects of environmental stressors on complex planktonic communities. It indicates that silver will negatively impact planktonic communities and may create shifts in their composition and functioning.


Assuntos
Eucariotos/crescimento & desenvolvimento , Processos Heterotróficos/efeitos dos fármacos , Invertebrados/crescimento & desenvolvimento , Processos Fototróficos/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Ecossistema , Luz
12.
Colloids Surf B Biointerfaces ; 173: 639-646, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30368211

RESUMO

Bacterial adhesion is a key step to prevent environmental problems called acid mine drainage or to improve leaching efficiency in industry, since it initiates and enhances bioleaching. Thus, to analyze bacterial adhesion and to understand this process is crucial. In this study atomic force microscopy equipped with a pyrite or chalcopyrite tip was applied to study the adhesion of Sulfobacillus thermosulfidooxidans. The results illustrate that planktonic cells of both pyrite- and sulfur-grown cells of S. thermosulfidooxidans show more affinity to pyrite than to chalcopyrite (adhesion forces 2 nN versus 0.13 nN). However, the interactions between bacteria and chalcopyrite can be strengthened, if the bacteria are brought into contact with the chalcopyrite. The biofilm cells show low affinity to either pyrite or chalcopyrite. A high content of proteins in the extracellular polymeric substances collected from planktonic cells of S. thermosulfidooxidans and a low content of proteins collected from biofilm EPS indicates that proteins play an important role in initial adhesion. Analysis of adhesion force-distance curves reveal that adhesion by pyrite-grown cells is a complex interaction involving several bonding forces.


Assuntos
Proteínas de Bactérias/química , Clostridiales/química , Cobre/química , Matriz Extracelular de Substâncias Poliméricas/química , Ferro/química , Plâncton/química , Sulfetos/química , Aderência Bacteriana , Biofilmes/crescimento & desenvolvimento , Clostridiales/citologia , Clostridiales/fisiologia , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Plâncton/crescimento & desenvolvimento , Eletricidade Estática , Propriedades de Superfície
13.
Curr Opin Biotechnol ; 55: 134-150, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30326407

RESUMO

Plankton produces numerous chemical compounds used in cosmetics and functional foods. They also play a key role in the carbon budget on the Earth. In a context of global change, it becomes important to understand the physiological response of these microorganisms to changing environmental conditions. Their adaptations and the response to specific environmental conditions are often restricted to a few active cells or individuals in large populations. Using analytical capabilities at the subnanoliter scale, microfluidic technology has also demonstrated a high potential in biological assays. Here, we review recent advances in microfluidic technologies to overcome the current challenges in high content analysis both at population and the single cell level.


Assuntos
Microfluídica/métodos , Plâncton/metabolismo , Pesquisa , Células/metabolismo , Humanos , Pressão Hidrostática , Plâncton/crescimento & desenvolvimento , Qualidade da Água
14.
J Chem Phys ; 149(21): 215102, 2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30525713

RESUMO

Pseudomonas aeruginosa changes its growth modes under different conditions. The bacteria in biofilm is more resistant to environmental stress compared to the planktonic mode of growth. The compositions of the inner plasma membrane for the two modes are noticeably different. Major lipid types are chosen from experiment to model the membrane in both modes of growth, and molecular dynamics simulation is used to study the properties of the membrane. The CHARMM36 lipid force field is used and tested against several experimental results. Our models include lipids containing cyclopropane in the middle of the sn-2 tail, namely, 1-palmitoyl-2-cis-11,12-methylene-stearic-acid-sn-glycero-3-phosphoethanolamine and 1-palmitoyl-2-cis-11,12-methylene-stearic-acid-sn-glycero-3-phosphoglycerol. The PE:PG ratio for the two model membranes is close, but the fraction of lipids composed of long-chain and cyclopropane-containing fatty acids changes significantly, causing differences between the two models. Compared to previous model membranes built for Escherichia coli, the inner membrane of P. aeruginosa has a longer averaged lipid tail length and a higher percentage of PG lipids, which are responsible for the changes in membrane properties like membrane thickness and stiffness. Most importantly, the comparison to experiments shows good agreements and encourages the model's use to study the behavior of proteins from P. aeruginosa associated with the membrane.


Assuntos
Biofilmes , Membrana Celular/metabolismo , Plâncton/metabolismo , Pseudomonas aeruginosa/metabolismo , Deutério/metabolismo , Ligação de Hidrogênio , Metabolismo dos Lipídeos , Lipídeos de Membrana/química , Modelos Biológicos , Simulação de Dinâmica Molecular , Plâncton/crescimento & desenvolvimento , Pseudomonas aeruginosa/crescimento & desenvolvimento
15.
FEMS Microbiol Ecol ; 94(12)2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-30265315

RESUMO

Subsurface environments contain a large proportion of planetary microbial biomass and harbor diverse communities responsible for mediating biogeochemical cycles important to groundwater used by human society for consumption, irrigation, agriculture and industry. Within the saturated zone, capillary fringe and vadose zones, microorganisms can reside in two distinct phases (planktonic or biofilm), and significant differences in community composition, structure and activity between free-living and attached communities are commonly accepted. However, largely due to sampling constraints and the challenges of working with solid substrata, the contribution of each phase to subsurface processes is largely unresolved. Here, we synthesize current information on the diversity and activity of shallow freshwater subsurface habitats, discuss the challenges associated with sampling planktonic and biofilm communities across spatial, temporal and geological gradients, and discuss how biofilms may be constrained within shallow terrestrial subsurface aquifers. We suggest that merging traditional activity measurements and sequencing/-omics technologies with hydrological parameters important to sediment biofilm assembly and stability will help delineate key system parameters. Ultimately, integration will enhance our understanding of shallow subsurface ecophysiology in terms of bulk-flow through porous media and distinguish the respective activities of sessile microbial communities from more transient planktonic communities to ecosystem service and maintenance.


Assuntos
Bactérias/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Água Doce/microbiologia , Sedimentos Geológicos/microbiologia , Água Subterrânea/microbiologia , Plâncton/crescimento & desenvolvimento , Bactérias/classificação , Humanos , Hidrologia , Microbiota , Plâncton/classificação
16.
Microb Pathog ; 124: 291-300, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30149130

RESUMO

Food plants Hungarian wax pepper (HWP) and Green Bell pepper (GBP), belonging to Capsicum annuum were utilized for biogenic fabrication of zero valent, nano-silver (AgNPs) through a photo-mediation procedure. In the bacterial strains evaluated, HWP/GBP AgNPs demonstrated effective bacteriostatic and bactericidal effect against Staphylococcus aureus. Time kill results portrayed that HWP/GBP nano-silver exhibited comparable bactericidal potency on S. aureus. Anti-biofilm potential of HWP/GBP AgNPs displayed significant effects at sub MIC levels, by triggering 50% biofilm reduction of the food spoilage microbe S. aureus, inferring that the anti-biofilm outcome is not dependent on antibacterial result, and this was confirmed by SEM and fluorescence studies. Histopathological analyses of S. aureus infected zebrafish liver did not display any abnormality changes such as extensive cell death and degeneration, upon treatment with HWP/GBP AgNPs and the zero-valent silver nanoparticles were comparatively less toxic and more operative in restraining the bioburden in S. aureus infected zebrafish model by a >1.7 log fold. Ability of light reduced HWP/GBP AgNPs to alleviate the in vitro and in vivo planktonic mode of growth and curb the biofilm formation of S. aureus is also demonstrated.


Assuntos
Biofilmes/efeitos dos fármacos , Capsicum/química , Nanopartículas Metálicas/química , Extratos Vegetais/farmacologia , Prata/farmacologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Plâncton/fisiologia , Extratos Vegetais/química , Prata/química , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Peixe-Zebra
17.
Environ Microbiol ; 20(10): 3798-3810, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30159999

RESUMO

Recent work suggests that temperature effects on marine heterotrophic bacteria are strongly seasonal, but few attempts have been made to concurrently assess them across trophic levels. Here, we estimated the temperature sensitivities (using activation energies, E) of autotrophic and heterotrophic microbial plankton net growth rates over an annual cycle in NE Atlantic coastal waters. Phytoplankton grew in winter and late autumn (0.41 ± 0.16 SE d-1 ) and decayed in the remaining months (-0.42 ± 0.10 d-1 ). Heterotrophic microbes shared a similar seasonality, with positive net growth for bacteria (0.14-1.48 d-1 ), while nanoflagellates had higher values (> 0.4 d-1 ) in winter and spring relative to the rest of the year (-0.46 to 0.29 d-1 ). Net growth rates activation energies showed similar dynamics in the three groups (-1.07 to 1.51 eV), characterized by maxima in winter, minima in summer and resumed increases in autumn. Microbial plankton E values were significantly correlated with nitrate concentrations as a proxy for nutrient availability. Nutrient-sufficiency (i.e., > 1 µmol l-1 nitrate) resulted in significantly higher activation energies of phytoplankton and heterotrophic nanoflagellates relative to nutrient-limited conditions. We suggest that only within spatio-temporal windows of both moderate bottom-up and top-down controls will temperature have a major enhancing effect on microbial growth.


Assuntos
Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Fitoplâncton/metabolismo , Processos Autotróficos , Ciclo do Carbono , Ecossistema , Processos Heterotróficos , Cinética , Nutrientes/metabolismo , Fitoplâncton/química , Fitoplâncton/crescimento & desenvolvimento , Plâncton/crescimento & desenvolvimento , Estações do Ano , Temperatura
18.
J Food Prot ; 81(9): 1481-1490, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30109972

RESUMO

Listeria species are ubiquitous in nature and can adapt to survive in a variety of niches, including food processing environments. Listeria species that colonize these environments may also have the potential to persist. Food safety strategies designed to manage these niches include regular cleaning and disinfection with proven sanitizers containing biocide-active compounds. Typically, these sanitizers are effective against bacteria growing under planktonic conditions, but their efficacy may be compromised when bacteria are contained in biofilms. The susceptibility of persistent Listeria isolates, i.e., those capable of forming biofilms, to a selection of sanitizers was investigated. A quaternary ammonium compound-based sanitizer was the biocide most effective against planktonic bacteria, with a MIC of 0.0015 to 0.006%. In contrast, ethanol-based sanitizers were the least effective. Although, no triclosan tolerance was observed for planktonic Listeria isolates, triclosan was the only biocide that resulted in a significant biomass reduction. Differences between Listeria species were observed; L. monocytogenes and L. welshimeri biofilms were more tolerant to quaternary ammonium compound-based sanitizers than were L. innocua biofilms. These findings extend our understanding of the application of commonly used sanitizers in the food industry and the efficacy of these sanitizers against Listeria species and their associated biofilms.


Assuntos
Biofilmes/crescimento & desenvolvimento , Desinfetantes , Listeria , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Contaminação de Alimentos/prevenção & controle , Listeria/fisiologia , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento
19.
BMC Genomics ; 19(1): 625, 2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-30134835

RESUMO

BACKGROUND: Pontimonas salivibrio strain CL-TW6T (=KCCM 90105 = JCM18206) was characterized as the type strain of a new genus within the Actinobacterial family Microbacteriaceae. It was isolated from a coastal marine environment in which members of Microbactericeae have not been previously characterized. RESULTS: The genome of P. salivibrio CL-TW6T was a single chromosome of 1,760,810 bp. Genomes of this small size are typically found in bacteria growing slowly in oligotrophic zones and said to be streamlined. Phylogenetic analysis showed it to represent a lineage originating in the Microbacteriaceae radiation occurring before the snowball Earth glaciations, and to have a closer relationship with some streamlined bacteria known through metagenomic data. Several genomic characteristics typical of streamlined bacteria are found: %G + C is lower than non-streamlined members of the phylum; there are a minimal number of rRNA and tRNA genes, fewer paralogs in most gene families, and only two sigma factors; there is a noticeable absence of some nonessential metabolic pathways, including polyketide synthesis and catabolism of some amino acids. There was no indication of any phage genes or plasmids, however, a system of active insertion elements was present. P. salivibrio appears to be unusual in having polyrhamnose-based cell wall oligosaccharides instead of mycolic acid or teichoic acid-based oligosaccharides. Oddly, it conducts sulfate assimilation apparently for sulfating cell wall components, but not for synthesizing amino acids. One gene family it has more of, rather than fewer of, are toxin/antitoxin systems, which are thought to down-regulate growth during nutrient deprivation or other stressful conditions. CONCLUSIONS: Because of the relatively small number of paralogs and its relationship to the heavily characterized Mycobacterium tuberculosis, we were able to heavily annotate the genome of P. salivibrio CL-TW6T. Its streamlined status and relationship to streamlined metagenomic constructs makes it an important reference genome for study of the streamlining concept. The final evolutionary trajectory of CL-TW6 T was to adapt to growth in a non-oligotrophic coastal zone. To understand that adaptive process, we give a thorough accounting of gene content, contrasting with both oligotrophic streamlined bacteria and large genome bacteria, and distinguishing between genes derived by vertical and horizontal descent.


Assuntos
Actinomycetales/crescimento & desenvolvimento , Actinomycetales/genética , Adaptação Biológica/genética , Água do Mar , Organismos Aquáticos/genética , Organismos Aquáticos/crescimento & desenvolvimento , Técnicas de Tipagem Bacteriana , DNA Bacteriano/análise , DNA Bacteriano/genética , Ecossistema , Estuários , Genoma Bacteriano , Filogenia , Plâncton/genética , Plâncton/crescimento & desenvolvimento , Análise de Sequência de DNA
20.
Huan Jing Ke Xue ; 39(3): 1151-1158, 2018 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965459

RESUMO

In order to investigate the characteristics of bacterioplankton in the spring in Zhushan Bay, Lake Taihu, the 16S rRNA gene of the bacterioplankton at four sampling sites in Zhushan Bay was sequenced by high-throughput sequencing using water samples collected from Yapugang, Shatanggang, Zhushanhunan, and Jiaoshan. The results showed that the coverage of the sequencing library was very high and could accurately represent the bacterioplankton community in the samples. The species richness of Jiaoshan was the highest, but the species evenness was lower. Cyanobacteria, Actinobacteria, Proteobacteria, and Bacteroidetes were the dominant phylum in Zhushan Bay. The average abundance of Cyanobacteria was as high as 64.73%, which indicated an outbreak of cyanobacteria bloom in the water. At the genus level, Anabaena, hgcI_clade, CL 500-29 _marine_group, Microcystis, Synechococcus, and Mycobacterium were predominant. The results of redundancy analysis (RDA) for the relationship between bacterioplankton and environmental factors showed that water temperature, chlorophyll a (Chl-a), ammonia nitrogen(NH4+-N), dissolved oxygen (DO), and phosphate (PO43--P)were the main environmental factors affecting the bacterioplankton community. Dissolved oxygen could significantly affect Microcystis; nutrient and water temperature also had an effect.


Assuntos
Bactérias/classificação , Lagos/microbiologia , Plâncton/classificação , Amônia/análise , Bactérias/crescimento & desenvolvimento , Baías , China , Clorofila A/análise , Monitoramento Ambiental , Oxigênio/análise , Fosfatos/análise , Plâncton/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Temperatura
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