scholarly journals Phage co-transport with hyphal-riding bacteria fuels bacterial invasion in water-unsaturated microbial ecosystems

2021 ◽  
Author(s):  
Xin You ◽  
René Kallies ◽  
Ingolf Kühn ◽  
Matthias Schmidt ◽  
Hauke Harms ◽  
...  
Keyword(s):  
Pythium Ultimum ◽  
Microbial Populations ◽  
Bacterial Invasion ◽  
Pseudomonas Putida Kt2440 ◽  
Air Gaps ◽  
E Coli ◽  
Microbial Ecosystems ◽  
Hyphal Transport ◽  
Transport Of Bacteria ◽  
New Habitats

Non-motile microbes enter new habitats often by co-transport with motile microorganisms. Here, we report on the ability of hyphal-riding bacteria to co-transport lytic phages and utilize them as "weapons" during colonization of new water-unsaturated habitats. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈ 0.6 phages bacteria-1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport mirrors macroecological invasion processes, we recommend hyphosphere systems with motile bacteria and co-transported phages as models for testing hypotheses in invasion ecology.

scholarly journals Phage co-transport with hyphal-riding bacteria fuels bacterial invasion in a water-unsaturated microbial model system

2021 ◽  
Author(s):  
Xin You ◽  
René Kallies ◽  
Ingolf Kühn ◽  
Matthias Schmidt ◽  
Hauke Harms ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Pythium Ultimum ◽  
Microbial Populations ◽  
Bacterial Invasion ◽  
Air Gaps ◽  
E Coli ◽  
Microbial Model ◽  
Hyphal Transport ◽  
Transport Of Bacteria ◽  
New Habitats

AbstractNonmotile microorganisms often enter new habitats by co-transport with motile microorganisms. Here, we report that also lytic phages can co-transport with hyphal-riding bacteria and facilitate bacterial colonization of a new habitat. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈0.6 phages bacteria−1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport seems analogous to macroecological invasion processes, hyphosphere systems with motile bacteria and co-transported phages could be useful models for testing hypotheses in invasion ecology.

A Comparison of Hand Washing Techniques To Remove Escherichia coli and Caliciviruses under Natural or Artificial Fingernails

2003 ◽  
Vol 66 (12) ◽  
pp. 2296-2301 ◽  
Author(s):  
CHIA-MIN LIN ◽  
FONE-MAO WU ◽  
HOI-KYUNG KIM ◽  
MICHAEL P. DOYLE ◽  
BARRY S. MICHAELS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Tap Water ◽  
Hand Washing ◽  
Microbial Populations ◽  
Liquid Soap ◽  
E Coli ◽  
Hand Sanitizer ◽  
Before And After ◽  
Escherichia Coli Jm109 ◽  
Viral Indicators

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P > 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P ≤ 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.

Reduction of Microorganisms on Citrus Fruit Surfaces during Packinghouse Processing

1998 ◽  
Vol 61 (7) ◽  
pp. 903-906 ◽  
Author(s):  
STEVEN PAO ◽  
G. ELDON BROWN
Keyword(s):  
Test Organism ◽  
Citrus Fruit ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Plate Counts ◽  
High Level ◽  
Inoculation Study ◽  
Fruit Surface

Citrus fruit surface microbial populations were evaluated following various packingline processes of seven Florida commercial packinghouses. At each packinghouse, six fruits (oranges or tangerines) were collected at each of four sampling points. The sampling was conducted in duplicate; thus, 336 fruit were evaluated during this survey. Average aerobic plate counts and yeast and mold counts on fruit surfaces before washing were about 4.0 log CFU/cm2 and 3.3 log CFU/cm2, respectively, and were reduced to 2.1 log CFU/cm2 and 1.3 log CFU/cm2, respectively, by packinghouse processing. Waxing alone reduced the average fruit surface aerobic plate counts and coliform counts from 3.7 log CFU/cm2 and 35.2 most probable number (MPN)/cm2, respectively, to 2.6 log CFU/cm2 and 1.4 MPN/cm2. No Escherichia coli was recovered from fruit at the end of packinghouse processing, and no salmonellae were found on fruit during the entire processing. In an inoculation study to test the effect of packinghouse processes, test organism E. coli was applied to fruit to achieve a high level (4.8 log CFU/cm2) of contamination. The average E. coli count was reduced about 2.4 log cycles by washing and rinsing with potable water (40 psi, 25 °C) for about 30 s. The combination of washing and waxing significantly reduced the inoculated level of E. coli from 4.8 to 1.4 log CFU/cm2.

scholarly journals Public-good driven release of heterogeneous resources leads to genotypic diversification of an isogenic yeast population in melibiose.

2021 ◽  
Author(s):  
Anjali Mahilkar ◽  
Phaniendra Alugoju ◽  
Vijendra Kavatalkar ◽  
Rajeshkannan E. ◽  
Jayadeva Bhat ◽  
...  
Keyword(s):  
Carbon Source ◽  
Public Good ◽  
Molecular Basis ◽  
Model System ◽  
Microbial Populations ◽  
Adaptive Diversification ◽  
E Coli ◽  
Hydrolysis Of ◽  
Convenient Model ◽  
Heterogeneous Resources

Adaptive diversification of an isogenic population, and its molecular basis has been a subject of a number of studies in the last few years. Microbial populations offer a relatively convenient model system to study this question. In this context, an isogenic population of bacteria (E. coli, B. subtilis, and Pseudomonas) has been shown to lead to genetic diversification in the population, when propagated for a number of generations. This diversification is known to occur when the individuals in the population have access to two or more resources/environments, which are separated either temporally or spatially. Here, we report adaptive diversification in an isogenic population of yeast, S. cerevisiae, when propagated in an environment containing melibiose as the carbon source. The diversification is driven due to a public good, enzyme α-galactosidase, leading to hydrolysis of melibiose into two distinct resources, glucose and galactose. The diversification is driven by a mutations at a single locus, in the GAL3 gene in the GAL/MEL regulon in the yeast.

Microbiological Status of Fresh Beef Cuts

2006 ◽  
Vol 69 (6) ◽  
pp. 1456-1459 ◽  
Author(s):  
J. D. STOPFORTH ◽  
M. LOPES ◽  
J. E. SHULTZ ◽  
R. R. MIKSCH ◽  
M. SAMADPOUR
Keyword(s):  
Total Coliform ◽  
Incidence Rates ◽  
Microbial Populations ◽  
Plate Count ◽  
Bacterial Populations ◽  
E Coli ◽  
Coliform Count ◽  
Processing Plants ◽  
Aerobic Plate Count ◽  
Whole Muscle

Fresh beef samples (n = 1,022) obtained from two processing plants in the Midwest (July to December 2003) were analyzed for levels of microbial populations (total aerobic plate count, total coliform count, and Escherichia coli count) and for the presence or absence of E. coli O157:H7 and Salmonella. A fresh beef cut sample was a 360-g composite of 6-g portions excised from the surface of 60 individual representative cuts in a production lot. Samples of fresh beef cuts yielded levels of 4.0 to 6.2, 1.1 to 1.8, and 0.8 to 1.0 log CFU/g for total aerobic plate count, total coliform count, and E. coli count, respectively. There did not appear to be substantial differences or obvious trends in bacterial populations on different cuts. These data may be useful in establishing a baseline or a benchmark of microbiological levels of contamination of beef cuts. Mean incidence rates of E. coli O157:H7 and Salmonella on raw beef cuts were 0.3 and 2.2%, respectively. Of the 1,022 samples analyzed, cuts testing positive for E. coli O157:H7 included top sirloin butt (0.9%) and butt, ball tip (2.1%) and for Salmonella included short loins (3.4%), strip loins (9.6%), rib eye roll (0.8%), shoulder clod (3.4%), and clod, top blade (1.8%). These data provide evidence of noticeable incidence of pathogens on whole muscle beef and raise the importance of such contamination on product that may be mechanically tenderized. Levels of total aerobic plate count, total coliform count, and E. coli count did not (P ≥ 0.05) appear to be associated with the presence of E. coli O157:H7 and Salmonella on fresh beef cuts. E. O157:H7 was exclusively isolated from cuts derived from the sirloin area of the carcass. Salmonella was exclusively isolated from cuts derived from the chuck, rib, and loin areas of the carcass. Results of this study suggest that contamination of beef cuts may be influenced by the region of the carcass from which they are derived.

scholarly journals Invasive Ability of an Escherichia coliStrain Isolated from the Ileal Mucosa of a Patient with Crohn’s Disease

1999 ◽  
Vol 67 (9) ◽  
pp. 4499-4509 ◽  
Author(s):  
Jerome Boudeau ◽  
Anne-Lise Glasser ◽  
Estelle Masseret ◽  
Bernard Joly ◽  
Arlette Darfeuille-Michaud
Keyword(s):  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Host Cell ◽  
Bacterial Invasion ◽  
Intestinal Epithelial ◽  
Invasive Ability ◽  
Ileal Mucosa ◽  
Gastrointestinal Infections ◽  
E Coli ◽  
Host Cell Membranes

ABSTRACT Crohn’s disease (CD) is an inflammatory bowel disease in whichEscherichia coli strains have been suspected of being involved. We demonstrated previously that ileal lesions of CD are colonized by E. coli strains able to adhere to intestinal Caco-2 cells but devoid of the virulence genes so far described in the pathogenic E. coli strains involved in gastrointestinal infections. In the present study we compared the invasive ability of one of these strains isolated from an ileal biopsy of a patient with CD, strain LF82, with that of reference enteroinvasive (EIEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteraggregative (EAggEC), enterohemorrhagic (EHEC), and diffusely adhering (DAEC)E. coli strains. Gentamicin protection assays showed thatE. coli LF82 was able to efficiently invade HEp-2 cells. Its invasive level was not significantly different from that of EIEC and EPEC strains (P > 0.5) but significantly higher than that of ETEC (P < 0.03), EHEC (P < 0.005), EAggEC (P < 0.004) and DAEC (P < 0.02) strains. Strain LF82 also demonstrated efficient ability to invade intestinal epithelial cultured Caco-2, Intestine-407, and HCT-8 cells. Electron microscopy examination of infected HEp-2 cells revealed the presence of numerous intracellular bacteria located in vacuoles or free in the host cell cytoplasm. In addition, the interaction of strain LF82 with epithelial cells was associated with the elongation of microvillar extensions that extruded from the host cell membranes and engulfed the bacteria. This internalization mechanism strongly resembles Salmonella- orShigella-induced macropinocytosis. The use of cytochalasin D and colchicine showed that the uptake of strain LF82 by HEp-2 cells was mediated by both an actin microfilament-dependent mechanism and microtubule involvement. In addition, strain LF82 survived for at least 24 h in HEp-2 and Intestine-407 cells and efficiently replicated intracellularly in HEp-2 cells. PCR and hybridization experiments did not reveal the presence of any of the genetic determinants encoding EIEC, EPEC, or ETEC proteins involved in bacterial invasion. Thus, these findings show that LF82, which colonized the ileal mucosa of a patient with CD, is a true invasive E. coli strain and suggest the existence of a new potentially pathogenic group of E. coli, which we propose be designated adherent-invasive E. coli.

Monitoring the Microbial Populations and Temperatures of Fresh Broccoli from Harvest to Retail Display†

2006 ◽  
Vol 69 (5) ◽  
pp. 1118-1125 ◽  
Author(s):  
R. DALLAIRE ◽  
D. I. LeBLANC ◽  
C. C. TRANCHANT ◽  
L. VASSEUR ◽  
P. DELAQUIS ◽  
...  
Keyword(s):  
Distribution System ◽  
Limit Of Detection ◽  
Fecal Coliforms ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Production And Distribution ◽  
Experimental Variability ◽  
Retail Display

Microbial populations and the temperature of fresh broccoli were monitored at several steps of a supply chain by sampling 33 distinct lots of locally grown produce over two seasons during harvest, storage, wholesale handling, and retail display. Imported broccoli was also sampled, but only at retail display. Microbiological analyses were conducted on the florets of 201 local and 60 imported broccoli samples to determine populations of total aerobic bacteria (aerobic colony count), fecal coliforms, Escherichia coli, and Listeria monocytogenes. All the samples had mean aerobic colony counts ranging between 4 and 6 log CFU/g, but L. monocytogenes was not detected (limit of detection = 100 CFU/g). Fecal coliforms and E. coli (limit of detection = 20 most probable number per 100 g) were found in 22 of 126 samples of local broccoli collected at various steps of the production and distribution system during the first season. None was found in 75 samples collected in the second season. Fecal coliforms and E. coli were found in 2 of 60 imported broccoli samples. Broccoli temperatures were relatively well controlled throughout the production and distribution system. No clear change in produce microbial populations was evident between harvest and retail display, during both sampling seasons. However, a large experimental variability was found, possibly associated with the high variability of the initial levels of microbial populations on broccoli at harvest.

scholarly journals Application of Signature-Tagged Mutagenesis for Identification ofEscherichia coli K1 Genes That Contribute to Invasion of Human Brain Microvascular Endothelial Cells

2000 ◽  
Vol 68 (9) ◽  
pp. 5056-5061 ◽  
Author(s):  
Julie L. Badger ◽  
Carol A. Wass ◽  
Scott J. Weissman ◽  
Kwang Sik Kim
Keyword(s):  
Endothelial Cells ◽  
Human Brain ◽  
Neonatal Rat ◽  
Microvascular Endothelial Cells ◽  
Selection Strategy ◽  
Bacterial Invasion ◽  
Brain Microvascular Endothelial Cells ◽  
E Coli ◽  
Microvascular Endothelial

ABSTRACT Escherichia coli K1 is the leading cause of gram-negative bacterial meningitis in neonates. It is principally due to our limited understanding of the pathogenesis of this disease that the morbidity and mortality rates remain unacceptably high. To identify genes required for E. coli K1 penetration of the blood-brain barrier (BBB), we used the negative selection strategy of signature-tagged transposon mutagenesis (STM) to screen mutants for loss or decreased invasion of human brain microvascular endothelial cells (HBMEC) which comprise the BBB. A total of 3,360 insertion mutants of E. coli K1 were screened, and potential HBMEC invasion mutants were subjected to a secondary invasion screen. Those mutants that failed to pass the serial invasion screens were then tested individually. Seven prototrophic mutants were found to exhibit significantly decreased invasive ability in HBMEC. We identifiedtraJ and five previously uncharacterized loci whose gene products are necessary for HBMEC invasion by E. coli K1. In addition, cnf1, a gene previously shown to play a role in bacterial invasion, was identified. More importantly, atraJ mutant was attenuated in penetration of the BBB in the neonatal rat model of experimental hematogenous meningitis. This is the first in vivo demonstration that traJ is involved in the pathogenesis of E. coli K1 meningitis.

scholarly journals Development of a Rapid Assay for Determining the Relative Abundance of Bacteria

2005 ◽  
Vol 71 (12) ◽  
pp. 8481-8490 ◽  
Author(s):  
Arlene K. Rowan ◽  
Russell J. Davenport ◽  
Jason R. Snape ◽  
David Fearnside ◽  
Michael R. Barer ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Microbial Populations ◽  
Ammonia Oxidizing Bacteria ◽  
Bacterial Cells ◽  
Target Region ◽  
E Coli ◽  
Sandwich Hybridization ◽  
Sandwich Hybridization Assay ◽  
Rrna Sequences

ABSTRACT A sandwich hybridization assay for high-throughput, rapid, simple, and inexpensive quantification of specific microbial populations was evaluated. The assay is based on the hybridization of a target rRNA with differentially labeled capture and detector probes. Betaproteobacterial ammonia-oxidizing bacteria (AOB) were selected as the target group for the study, since they represent a phylogenetically coherent group of organisms that perform a well-defined geochemical function in natural and engineered environments. Reagent concentrations, probe combinations, and washing, blocking, and hybridization conditions were optimized to improve signal and reduce background. The detection limits for the optimized RNA assay were equivalent to approximately 103 to 104 and 104 to 105 bacterial cells, respectively, for E. coli rRNA and RNA extracted from activated sludge, by using probes targeting the majority of bacteria. Furthermore, the RNA assay had good specificity, permitted discrimination of rRNA sequences that differed by a 2-bp mismatch in the probe target region, and could distinguish the sizes of AOB populations in nitrifying and nonnitrifying wastewater treatment plants.

scholarly journals Efficacy of Three Light Technologies for Reducing Microbial Populations in Liquid Suspensions

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Angeliki Birmpa ◽  
Apostolos Vantarakis ◽  
Spyros Paparrodopoulos ◽  
Paul Whyte ◽  
James Lyng
Keyword(s):  
Treatment Time ◽  
Limit Of Detection ◽  
Foodborne Pathogen ◽  
Microbial Populations ◽  
Liquid Matrix ◽  
E Coli ◽  
Bactericidal Efficacy ◽  
The Common ◽  
Liquid Suspensions ◽  
Uv C

The aim of the current study was to evaluate the effectiveness of three nonthermal light technologies (NUV-Vis, continuous UV, and HILP) on their ability to inactivateEscherichia coliK12 andListeria innocua.  E. coliK12 was selected as a representative microorganism for the enterohaemorrhagic foodborne pathogenE. coliO157:H7 andL. innocuaas a surrogate microorganism for the common foodborne pathogenListeria monocytogenes, respectively. The liquid matrix used for the disinfection experiments was a liquid matrix (MRD solution). The results of the present study show that the HILP treatment inactivated bothE. coliandL. innocuamore rapidly and effectively than either continuous UV-C or NUV-vis treatment. With HILP at 2.5 cm from the lamp,E. coliandL. innocuapopulations were reduced by 3.07 and 3.77 log10CFU/mL, respectively, after a 5 sec treatment time, and were shown to be below the limit of detection (<0.22 log10CFU/mL) following 30 sec exposure to HILP (106.2 J/cm2). These studies demonstrate the bactericidal efficacy of alternative nonthermal light technologies and their potential as decontamination strategies in the food industry.

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