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The Journal of Animal Ecology May 2015Despite growing interest in ecological consequences of parasitism in food webs, relatively little is known about effects of parasites on long-term population dynamics of...
Despite growing interest in ecological consequences of parasitism in food webs, relatively little is known about effects of parasites on long-term population dynamics of non-host species or about whether such effects are density or trait mediated. We studied a tri-trophic food chain comprised of (i) a bacterial basal resource (Serratia fonticola), (ii) an intermediate consumer (Paramecium caudatum), (iii) a top predator (Didinium nasutum) and (iv) a parasite of the intermediate consumer (Holospora undulata). A fully factorial experimental manipulation of predator and parasite presence/absence was combined with analyses of population dynamics, modelling and analyses of host (Paramecium) morphology and behaviour. Predation and parasitism each reduced the abundance of the intermediate consumer (Paramecium), and parasitism indirectly reduced the abundance of the basal resource (Serratia). However, in combination, predation and parasitism had non-additive effects on the abundance of the intermediate consumer, as well as on that of the basal resource. In both cases, the negative effect of parasitism seemed to be effaced by predation. Infection of the intermediate consumer reduced predator abundance. Modelling and additional experimentation revealed that this was most likely due to parasite reduction of intermediate host abundance (a density-mediated effect), as opposed to changes in predator functional or numerical response. Parasitism altered morphological and behavioural traits, by reducing host cell length and increasing the swimming speed of cells with moderate parasite loads. Additional tests showed no significant difference in Didinium feeding rate on infected and uninfected hosts, suggesting that the combination of these modifications does not affect host vulnerability to predation. However, estimated rates of encounter with Serratia based on these modifications were higher for infected Paramecium than for uninfected Paramecium. A mixture of density-mediated and trait-mediated indirect effects of parasitism on non-host species creates rich and complex possibilities for effects of parasites in food webs that should be included in assessments of possible impacts of parasite eradication or introduction.
Topics: Animals; Behavior, Animal; Ciliophora; Food Chain; Holosporaceae; Host-Pathogen Interactions; Paramecium caudatum; Population Dynamics; Predatory Behavior; Serratia
PubMed: 25382389
DOI: 10.1111/1365-2656.12317 -
Impact of operational conditions on drinking water biofilm dynamics and coliform invasion potential.Applied and Environmental Microbiology May 2024Biofilms within drinking water distribution systems serve as a habitat for drinking water microorganisms. However, biofilms can negatively impact drinking water quality...
UNLABELLED
Biofilms within drinking water distribution systems serve as a habitat for drinking water microorganisms. However, biofilms can negatively impact drinking water quality by causing water discoloration and deterioration and can be a reservoir for unwanted microorganisms. In this study, we investigated whether indicator organisms for drinking water quality, such as coliforms, can settle in mature drinking water biofilms. Therefore, a biofilm monitor consisting of glass rings was used to grow and sample drinking water biofilms. Two mature drinking water biofilms were characterized by flow cytometry, ATP measurements, confocal laser scanning microscopy, and 16S rRNA sequencing. Biofilms developed under treated chlorinated surface water supply exhibited lower cell densities in comparison with biofilms resulting from treated groundwater. Overall, the phenotypic as well as the genotypic characteristics were significantly different between both biofilms. In addition, the response of the biofilm microbiome and possible biofilm detachment after minor water quality changes were investigated. Limited changes in pH and free chlorine addition, to simulate operational changes that are relevant for practice, were evaluated. It was shown that both biofilms remained resilient. Finally, mature biofilms were prone to invasion of the coliform, . After spiking low concentrations (i.e., ±100 cells/100 mL) of the coliform to the corresponding bulk water samples, the coliforms were able to attach and get established within the mature biofilms. These outcomes emphasize the need for continued research on biofilm detachment and its implications for water contamination in distribution networks.
IMPORTANCE
The revelation that even low concentrations of coliforms can infiltrate into mature drinking water biofilms highlights a potential public health concern. Nowadays, the measurement of coliform bacteria is used as an indicator for fecal contamination and to control the effectiveness of disinfection processes and the cleanliness and integrity of distribution systems. In Flanders (Belgium), 533 out of 18,840 measurements exceeded the established norm for the coliform indicator parameter in 2021; however, the source of microbial contamination is mostly unknown. Here, we showed that mature biofilms, are susceptible to invasion of . These findings emphasize the importance of understanding and managing biofilms in drinking water distribution systems, not only for their potential to influence water quality, but also for their role in harboring and potentially disseminating pathogens. Further research into biofilm detachment, long-term responses to operational changes, and pathogen persistence within biofilms is crucial to inform strategies for safeguarding drinking water quality.
Topics: Biofilms; Drinking Water; Enterobacteriaceae; RNA, Ribosomal, 16S; Water Quality; Water Purification; Water Microbiology; Water Supply
PubMed: 38647288
DOI: 10.1128/aem.00042-24 -
Frontiers in Microbiology 2021Mosquitoes have evolved an effective innate immune system. The mosquito gut accommodates various microbes, which play a crucial role in shaping the mosquito immune...
Mosquitoes have evolved an effective innate immune system. The mosquito gut accommodates various microbes, which play a crucial role in shaping the mosquito immune system during evolution. The resident bacteria in the gut microbiota play an essential role in priming basal immunity. In this study, we show that antibacterial immunity in can be enhanced by priming via a sugar meal supplemented with bacteria. S1 and sp. Ag1 are gut bacteria in mosquitoes. The intrathoracic injection of the two bacteria can result in an acute hemocoelic infection in the naïve mosquitoes with mortality of ∼40% at 24 h post-infection. However, the or primed mosquitoes showed a better 24 h survival upon the bacterial challenge. The priming confers the protection with a certain degree of specificity, the primed mosquitoes had a better survival upon the but not challenge, and the primed mosquitoes had a better survival upon the but not challenge. To understand the priming-mediated immune enhancement, the transcriptomes were characterized in the mosquitoes of priming as well as priming plus challenges. The RNA-seq was conducted to profile 10 transcriptomes including three samples of priming conditions (native microbiota, priming, and priming), six samples of priming plus challenges with the two bacteria, and one sample of injury control. The three priming regimes resulted in distinctive transcriptomic profiles with about 60% of genes affected by both bacteria. Upon challenges, different primed mosquitoes displayed different transcriptomic patterns in response to different bacteria. When a primed cohort was challenged with a heterogenous bacterium, more responsive genes were observed than when challenged with a homogenous bacterium. As expected, many canonical immune genes were responsive to the priming and challenge, but much more non-immune genes with various functions were also responsive in the contexts, which implies that the prior priming triggers a delicately coordinated systemic regulation that results in an enhanced immunity against the subsequent challenge. Besides the participation of typical immune pathways, the transcriptome data suggest the involvement of lysosome and metabolism in the context. Overall, this study demonstrated a trained immunity via priming with bacteria in diet.
PubMed: 33995307
DOI: 10.3389/fmicb.2021.649213 -
Frontiers in Microbiology 2020The increasing occurrence of multidrug-resistant (MDR) extended-spectrum β-lactamase- (ESBL) and/or AmpC β-lactamase-producing Enterobacteriaceae in health care...
Occurrence, Phenotypic and Molecular Characterization of Extended-Spectrum- and AmpC- β-Lactamase Producing Enterobacteriaceae Isolated From Selected Commercial Spinach Supply Chains in South Africa.
The increasing occurrence of multidrug-resistant (MDR) extended-spectrum β-lactamase- (ESBL) and/or AmpC β-lactamase-producing Enterobacteriaceae in health care systems, the environment and fresh produce is a serious concern globally. Production practices, processing and subsequent consumption of contaminated raw fruit and vegetables represent a possible human transmission route. The purpose of this study was to determine the presence of ESBL/AmpC-producing Enterobacteriaceae in complete spinach supply chains and to characterize the isolated strains phenotypically (antimicrobial resistance profiles) and genotypically (ESBL/AmpC genetic determinants, detection of class 1, 2, and 3 integrons). Water, soil, fresh produce, and contact surface samples ( = 288) from two commercial spinach production systems were screened for ESBL/AmpC-producing Enterobacteriaceae. In total, 14.58% (42/288) of the samples were found to be contaminated after selective enrichment, plating onto chromogenic media and matrix-assisted laser desorption ionization time-of-flight mass spectrometry identity confirmation of presumptive ESBL/AmpC isolates. This included 15.28% (11/72) water and 12.12% (16/132) harvested- and processed spinach, while 25% (15/60) retail spinach samples were found to be contaminated with an increase in isolate abundance and diversity in both scenarios. Dominant species identified included (45.86%), (20.83%), and (18.75%). In total, 48 (81.36%) isolates were phenotypically confirmed as ESBL/AmpC-producing Enterobacteriaceae of which 98% showed a MDR phenotype. Genotypic characterization (PCR of ESBL/AmpC resistance genes and integrons) further revealed the domination of the CTX-M Group 1 ESBL type, followed by TEM and SHV; whilst the CIT-type was the only plasmid-mediated AmpC genetic determinant detected. Integrons were detected in 79.17% ( = 38) of the confirmed ESBL/AmpC-producing isolates, of which we highlight the high prevalence of class 3 integrons, detected in 72.92% ( = 35) of the isolates, mostly in . Class 2 integrons were not detected in this study. This is the first report on the prevalence of ESBL/AmpC-producing Enterobacteriaceae isolated throughout commercial spinach production systems harboring class 1 and/or class 3 integrons in Gauteng Province, South Africa. The results add to the global knowledge base regarding the prevalence and characteristics of ESBL/AmpC-producing Enterobacteriaceae in fresh vegetables and the agricultural environment required for future risk analysis.
PubMed: 32351477
DOI: 10.3389/fmicb.2020.00638 -
High-throughput Nov 2018Beta-lactam resistant bacteria, which are commonly resident in tertiary hospitals, have emerged as a worldwide health problem because of ready-to-eat vegetable intake....
Beta-lactam resistant bacteria, which are commonly resident in tertiary hospitals, have emerged as a worldwide health problem because of ready-to-eat vegetable intake. We aimed to characterize the genes that provide resistance to beta-lactam antibiotics in Enterobacteriaceae, isolated from five commercial salad brands for human consumption in Mexico City. In total, twenty-five samples were collected, grown in blood agar plates, and the bacteria were biochemistry identified and antimicrobial susceptibility testing was done. The carried family genes were identified by endpoint PCR and the specific genes were confirmed with whole genome sequencing (WGS) by Next Generation Sequencing (NGS). Twelve positive cultures were identified and their microbiological distribution was as follows: 8.3% for ( = 1), 8.3% for ( = 1), 16.7% for ( = 2), 16.7% for ( = 2), and 50% ( = 6) for . The endpoint PCR results showed 11 colonies positive for BIL (91.7%), 11 for SHV (91.7%), 11 for CTX (97.7%), 12 for DHA (100%), four for VIM (33.3%), two for OXA (16.7%), two for IMP (16.7%), one for KPC (8.3%), and one for TEM (8.3%) gen; all samples were negative for ROB, CMY, P, CFX and LAP gene. The sequencing analysis revealed a specific genotype for (blaSHV-12, blaCTX-M-15, blaDHA-1, blaKPC-2); (blaSHV-1, blaCTX-M-3, blaDHA-1, blaVIM-2); (blaSHV-12, blaCTX-M-15, blaDHA-1); (blaSHV-12, blaVIM-1, blaDHA-1); and, (blaSHV-1, blaCTX-M-1, blaDHA-1, blaVIM-2, blaOXA-9). Our results indicate that beta-lactam-resistant bacteria have acquired integrons with a different number of genes that provide pan-resistance to beta-lactam antibiotics, including penicillins, oxacillins, cefalosporins, monobactams, carbapenems, and imipenems.
PubMed: 30477153
DOI: 10.3390/ht7040036 -
Antibiotics (Basel, Switzerland) Jan 2023The aim of this research is to profile the chemical composition of the essential oil (EO) extracted from the aerial parts of () and to evaluate its antioxidant,...
The aim of this research is to profile the chemical composition of the essential oil (EO) extracted from the aerial parts of () and to evaluate its antioxidant, antibacterial and insecticidal activities on adults. Gas chromatography coupled with mass spectrometry (GC/MS) revealed a total of 27 constituents in EO of , which accounted for 99.08% of its constituents. Carvacrol (57.32%) was a main component, followed by -cymene (14.70%) and -terpinene (9.84%). The antioxidant activity of EO was investigated using DPPH (1,1-diphenyl-2-picrylhydrazyl), FRAP (Ferric reducing antioxidant power), and TCA (the total antioxidant capacity) methods. This EO exhibited a remarkable antiradical and reducing power against DPPH (IC = 2.855 ± 0.018μL/mL), FRAP (EC = 0.124 ± 0.013µL/mL) and TCA (IC = 14.099 ± 0.389 mg AAE/g of the EO). The antibacterial tests in vitro, using the disc and dilution methods, were carried out on nine pathogenic bacteria isolated from the hospital patients, such as , , , , , , and . The EO demonstrated a considerable antibacterial activity with minimum inhibitory concentrations (MIC) from 2 to 8 µL/mL against all strains except (MIC = 32 µL/mL). Regarding the insecticidal activity, the fumigation test indicated a high efficacy (100% mortality), and a lethal dose of LD = 17 ± 0.53 μL/L air was found after 24 h of exposureTherefore, EO could be utilized as a natural antioxidant, antibiotic and biopesticides.
PubMed: 36671374
DOI: 10.3390/antibiotics12010174 -
Antimicrobial Agents and Chemotherapy Nov 2011The subclass B2 metallo-β-lactamase (MBL) Sfh-I from Serratia fonticola UTAD54 was cloned and overexpressed in Escherichia coli. The recombinant protein binds one...
The subclass B2 metallo-β-lactamase (MBL) Sfh-I from Serratia fonticola UTAD54 was cloned and overexpressed in Escherichia coli. The recombinant protein binds one equivalent of zinc, as shown by mass spectrometry, and preferentially hydrolyzes carbapenem substrates. However, compared to other B2 MBLs, Sfh-I also shows limited hydrolytic activity against some additional substrates and is not inhibited by a second equivalent of zinc. These data confirm Sfh-I to be a subclass B2 metallo-β-lactamase with some distinctive properties.
Topics: Carbapenems; Escherichia coli; Serratia; beta-Lactamases
PubMed: 21876065
DOI: 10.1128/AAC.00429-11 -
Genome Announcements Nov 2013Serratia fonticola UTAD54 is an environmental isolate that is resistant to carbapenems due to the presence of a class A carbapenemase and a metallo-β-lactamase that are...
Serratia fonticola UTAD54 is an environmental isolate that is resistant to carbapenems due to the presence of a class A carbapenemase and a metallo-β-lactamase that are unique to this strain. Its draft genome sequence was obtained to clarify the molecular basis of its carbapenem resistance and identify the genomic context of its carbapenem resistance determinants.
PubMed: 24285645
DOI: 10.1128/genomeA.00970-13 -
Genome Announcements Nov 2013Plant growth-promoting rhizobacteria (PGPR), found in the rhizospheric region of plants, not only suppress plant disease, but also directly improve plant health by...
Plant growth-promoting rhizobacteria (PGPR), found in the rhizospheric region of plants, not only suppress plant disease, but also directly improve plant health by improving the availability of nutrients and by providing phytostimulants. Herein, we report the high-quality genome sequence of Serratia fonticola strain AU-P3(3), a PGPR of the pea plant, which confers phosphate solubilization, indole-3-acetic acid production, ammonia production, hydrogen cyanide (HCN) production, and siderophore production and also confers activity against Rhizoctonia species. The 5.02-Mb genome sequence contains genes related to plant growth promotion and biocontrol activities.
PubMed: 24233592
DOI: 10.1128/genomeA.00946-13 -
Antimicrobial Agents and Chemotherapy Jan 2010Pseudomonas luteola (formerly classified as CDC group Ve-1 and named Chryseomonas luteola) is an unusual pathogen implicated in rare but serious infections in humans. A...
Pseudomonas luteola (formerly classified as CDC group Ve-1 and named Chryseomonas luteola) is an unusual pathogen implicated in rare but serious infections in humans. A novel beta-lactamase gene, bla(LUT-1), was cloned from the whole-cell DNA of the P. luteola clinical isolate LAM, which had a weak narrow-spectrum beta-lactam-resistant phenotype, and expressed in Escherichia coli. This gene encoded LUT-1, a 296-amino-acid Ambler class A beta-lactamase with a pI of 6 and a theoretical molecular mass of 28.9 kDa. The catalytic efficiency of this enzyme was higher for cephalothin, cefuroxime, and cefotaxime than for penicillins. It was found to be 49% to 59% identical to other Ambler class A beta-lactamases from Burkholderia sp. (PenA to PenL), Ralstonia eutropha (REUT), Citrobacter sedlakii (SED-1), Serratia fonticola (FONA and SFC-1), Klebsiella sp. (KPC and OXY), and CTX-M extended-spectrum beta-lactamases. No gene homologous to the regulatory ampR genes of class A beta-lactamases was found in the vicinity of the bla(LUT-1) gene. The entire bla(LUT-1) coding region was amplified by PCR and sequenced in five other genetically unrelated P. luteola strains (including the P. luteola type strain). A new variant of bla(LUT-1) was found for each strain. These genes (named bla(LUT-2) to bla(LUT-6)) had nucleotide sequences 98.1 to 99.5% identical to that of bla(LUT-1) and differing from this gene by two to four nonsynonymous single nucleotide polymorphisms. The bla(LUT) gene was located on a 700- to 800-kb chromosomal I-CeuI fragment, the precise size of this fragment depending on the P. luteola strain.
Topics: Amino Acid Sequence; Anti-Bacterial Agents; Catheters, Indwelling; Chromosomes, Bacterial; Cloning, Molecular; Electrophoresis, Gel, Pulsed-Field; Genes, Bacterial; Genetic Variation; Isoelectric Focusing; Kinetics; Microbial Sensitivity Tests; Molecular Sequence Data; Phylogeny; Plasmids; Pseudomonas; Pseudomonas Infections; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Substrate Specificity; beta-Lactamases
PubMed: 19884377
DOI: 10.1128/AAC.00427-09