Acanthamoeba castellanii Promotes the Survival of Vibrio parahaemolyticus

ABSTRACT Vibrio parahaemolyticus is a food-borne pathogen that naturally inhabits both marine and estuarine environments. Free-living protozoa exist in similar aquatic environments and function to control bacterial numbers by grazing on free-living bacteria. Protozoa also play an important role in the survival and spread of some pathogenic species of bacteria. We investigated the interaction between the protozoan Acanthamoeba castellanii and the bacterium Vibrio parahaemolyticus. We found that Acanthamoeba castellanii does not prey on Vibrio parahaemolyticus but instead secretes a factor that promotes the survival of Vibrio parahaemolyticus in coculture. These studies suggest that protozoa may provide a survival advantage to an extracellular pathogen in the environment.

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Mitigation of Expression of Virulence Genes in Legionella pneumophila Internalized in the Free-Living Amoeba Willaertia magna C2c Maky

Pathogens ◽

10.3390/pathogens9060447 ◽

2020 ◽

Vol 9 (6) ◽

pp. 447 ◽

Cited By ~ 1

Author(s):

Rayane Mouh Mameri ◽

Jacques Bodennec ◽

Laurent Bezin ◽

Sandrine Demanèche

Keyword(s):

Gene Expression ◽

Legionella Pneumophila ◽

Virulence Genes ◽

Natural Habitat ◽

Acanthamoeba Castellanii ◽

Severe Form ◽

Aquatic Environments ◽

Free Living ◽

Intracellular Parasites ◽

Free Living Amoeba

Legionella pneumophila is a human pathogen responsible for a severe form of pneumonia named Legionnaire disease. Its natural habitat is aquatic environments, being in a free state or intracellular parasites of free-living amoebae, such as Acanthamoeba castellanii. This pathogen is able to replicate within some amoebae. Willaertia magna C2c Maky, a non-pathogenic amoeba, was previously demonstrated to resist to L. pneumophila and even to be able to eliminate the L. pneumophila strains Philadelphia, Lens, and Paris. Here, we studied the induction of seven virulence genes of three L. pneumophila strains (Paris, Philadelphia, and Lens) within W. magna C2c Maky in comparison within A. castellanii and with the gene expression level of L. pneumophila strains alone used as controls. We defined a gene expression-based virulence index to compare easily and without bias the transcript levels in different conditions and demonstrated that W. magna C2c Maky did not increase the virulence of L. pneumophila strains in contrast to A. castellanii. These results confirmed the non-permissiveness of W. magna C2c Maky toward L. pneumophila strains.

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Behavior of Yersinia enterocolitica in the Presence of the Bacterivorous Acanthamoeba castellanii

Applied and Environmental Microbiology ◽

10.1128/aem.01915-13 ◽

2013 ◽

Vol 79 (20) ◽

pp. 6407-6413 ◽

Cited By ~ 16

Author(s):

E. Lambrecht ◽

J. Baré ◽

I. Van Damme ◽

W. Bert ◽

K. Sabbe ◽

...

Keyword(s):

Yersinia Enterocolitica ◽

Pathogenic Bacteria ◽

Acanthamoeba Castellanii ◽

Ecological Niches ◽

Free Living ◽

Content Type ◽

Food Borne ◽

Transmission Electron ◽

Set Up ◽

The Impact

ABSTRACTFree-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction betweenYersinia enterocolitica, an important food-borne pathogen, and the free-living amoebaAcanthamoeba castellaniiwas studied. Several cocultivation assays were set up to assess the resistance ofY. enterocoliticatoA. castellaniipredation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that allY. enterocoliticastrains persist in association withA. castellaniifor at least 14 days, and associations withA. castellaniienhanced survival ofYersiniaunder nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of oneYersiniastrain showed temperature- and time-dependent permeabilization. Intraprotozoan survival ofY. enterocoliticadepended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate theYersiniacells inside the amoebae. AsYersiniaandAcanthamoebashare similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology ofY. enterocolitica.

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The human pathogenic vibrios – A public health update with environmental perspectives

Epidemiology and Infection ◽

10.1017/s0950268800030326 ◽

1989 ◽

Vol 103 (1) ◽

pp. 1-34 ◽

Cited By ~ 61

Author(s):

P. A. West

Keyword(s):

Public Health ◽

Acute Infection ◽

Aquatic Environments ◽

Free Living ◽

Liver Disorders ◽

Naturally Occurring ◽

Pathogenic Vibrio ◽

Ear Infections ◽

Pathogenic Vibrios ◽

Living Bacteria

PathogenicVibriospecies are naturally-occurring bacteria in freshwater and saline aquatic environments. Counts of free-living bacteria in water are generally less than required to induce disease. Increases in number of organisms towards an infective dose can occur as water temperatures rise seasonally followed by growth and concentration of bacteria on higher animals, such as chitinous plankton, or accumulation by shellfish and seafood. PathogenicVibriospecies must elaborate a series of virulence factors to elicit disease in humans.Activities which predispose diarrhoeal and extraintestinal infections include ingestion of seafood and shellfish and occupational or recreational exposure to natural aquatic environments, especially those above 20 °C. Travel to areas endemic for diseases due to pathogenicVibriospecies may be associated with infections. Host risk factors strongly associated with infections are lack of gastric acid and liver disorders.Involvement of pathogenicVibriospecies in cases of diarrhoea should be suspected especially if infection is associated with ingestion of seafood or shellfish, raw or undercooked, in the previous 72 h.Vibriospecies should be suspected in any acute infection associated with wounds sustained or exposed in the marine or estuarine environment. Laboratories serving coastal areas where infection due to pathogenic Vibrio species are most likely to occur should consider routine use of TCBS agar and other detection regimens for culture ofVibriospecies from faeces, blood and samples from wound and ear infections.

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NhaA, an Na+/H+ Antiporter Involved in Environmental Survival of Vibrio cholerae

Journal of Bacteriology ◽

10.1128/jb.182.10.2937-2944.2000 ◽

2000 ◽

Vol 182 (10) ◽

pp. 2937-2944 ◽

Cited By ~ 32

Author(s):

Sophie Vimont ◽

Patrick Berche

Keyword(s):

Vibrio Cholerae ◽

Vibrio Parahaemolyticus ◽

Natural Habitat ◽

Aquatic Environments ◽

Wild Type ◽

Transcriptional Fusion ◽

Free Living ◽

E Coli ◽

Functional Homology ◽

Wide Range

ABSTRACT Vibrio cholerae, the agent of cholera, is a normal inhabitant of aquatic environments, in which it survives under a wide range of conditions of pH and salinity. In this work, we identified thenhaA gene in a wild-type epidemic strain of V. cholerae O1. nhaA encodes a protein of 382 amino acids that is very similar to the proteins NhaA of Vibrio parahaemolyticus, Vibrio alginolyticus (∼87% identity), and Escherichia coli (56% identity). V. cholerae NhaA complements an E. coli nhaA mutant, enabling it to grow in 700 mM NaCl, pH 7.5, indicating functional homology to E. coli NhaA. However, unlike E. coli, the growth of a nhaA-inactivated mutant ofV. cholerae was not restricted at various pH and NaCl concentrations, although it was inhibited in the presence of 120 mM LiCl at pH 8.5. Nevertheless, using a nhaA′-lacZtranscriptional fusion, we observed induction of nhaAtranscription by Na+, Li+, and K+. These results strongly suggest that NhaA is an Na+/H+ antiporter contributing to the Na+/H+ homeostasis of V. cholerae. nhaA-related sequences were detected in all strains ofV. cholerae from the various serogroups. This gene is presumably involved in the survival and persistence of free-living bacteria in their natural habitat.

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Intracellular Behaviour of Three Legionella pneumophila Strains within Three Amoeba Strains, Including Willaertia magna C2c Maky

Pathogens ◽

10.3390/pathogens9020105 ◽

2020 ◽

Vol 9 (2) ◽

pp. 105 ◽

Cited By ~ 8

Author(s):

Issam Hasni ◽

Antoine Jarry ◽

Benjamin Quelard ◽

Antoine Carlino ◽

Jean-Baptiste Eberst ◽

...

Keyword(s):

Legionella Pneumophila ◽

Acanthamoeba Castellanii ◽

Aquatic Environments ◽

Intracellular Pathogen ◽

Planktonic Cells ◽

Intracellular Growth ◽

Free Living ◽

Intracellular Parasites ◽

Elimination Mechanism

Legionella pneumophila is a facultative intracellular pathogen found in aquatic environments as planktonic cells within biofilms and as intracellular parasites of free-living amoebae such as Acanthamoeba castellanii. This pathogen bypasses the elimination mechanism to replicate within amoebae; however, not all amoeba species support the growth of L. pneumophila. Willaertia magna C2c Maky, a non-pathogenic amoeba, was previously demonstrated to possess the ability to eliminate the L. pneumophila strain Paris. Here, we study the intracellular behaviour of three L. pneumophila strains (Paris, Philadelphia, and Lens) within W. magna C2c Maky and compare this strain to A. castellanii and W. magna Z503, which are used as controls. We observe the intracellular growth of strain Lens within W. magna Z503 and A. castellanii at 22 °C and 37 °C. Strain Paris grows within A. castellanii at any temperature, while it only grows at 22 °C within W. magna Z503. Strain Philadelphia proliferates only within A. castellanii at 37 °C. Within W. magna C2c Maky, none of the three legionella strains exhibit intracellular growth. Additionally, the ability of W. magna C2c Maky to decrease the number of internalized L. pneumophila is confirmed. These results support the idea that W. magna C2c Maky possesses unique behaviour in regard to L. pneumophila strains.

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Particle Collection in Imhoff Sedimentation Cones Enriches Both Motile Chemotactic and Particle-Attached Bacteria

Frontiers in Microbiology ◽

10.3389/fmicb.2021.643730 ◽

2021 ◽

Vol 12 ◽

Author(s):

Anneke Heins ◽

Greta Reintjes ◽

Rudolf I. Amann ◽

Jens Harder

Keyword(s):

Amplicon Sequencing ◽

Enrichment Factors ◽

Free Living ◽

Particle Collection ◽

16S Rrna Amplicon Sequencing ◽

Heterotrophic Microorganisms ◽

Attached Bacteria ◽

Bacterial Aggregates ◽

And Function ◽

Living Bacteria

Marine heterotrophic microorganisms remineralize about half of the annual primary production, with the microbiomes on and around algae and particles having a major contribution. These microbiomes specifically include free-living chemotactic and particle-attached bacteria, which are often difficult to analyze individually, as the standard method of size-selective filtration only gives access to particle-attached bacteria. In this study, we demonstrated that particle collection in Imhoff sedimentation cones enriches microbiomes that included free-living chemotactic bacteria and were distinct from particle microbiomes obtained by filtration or centrifugation. Coastal seawater was collected during North Sea phytoplankton spring blooms, and the microbiomes were investigated using 16S rRNA amplicon sequencing and fluorescence microscopy. Enrichment factors of individual operational taxonomic units (OTUs) were calculated for comparison of fractionated communities after separation with unfractionated seawater communities. Filtration resulted in a loss of cells and yielded particle fractions including bacterial aggregates, filaments, and large cells. Centrifugation had the lowest separation capacity. Particles with a sinking rate of >2.4 m day–1 were collected in sedimentation cones as a bottom fraction and enriched in free-living chemotactic bacteria, i.e., Sulfitobacter, Pseudoalteromonas, and Vibrio. Subfractions of these bottom fractions, obtained by centrifugation, showed enrichment of either free-living or particle-attached bacteria. We identified five distinct enrichment patterns across all separation techniques: mechano-sensitive and mechano-stable free-living bacteria and three groups of particle-attached bacteria. Simultaneous enrichment of particle-attached and chemotactic free-living bacteria in Imhoff sedimentation cones is a novel experimental access to these groups providing more insights into the diversity, structure, and function of particle-associated microbiomes, including members of the phycosphere.

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Diversity of Bacterial Communities in Contrasting Aquatic Environments: Lake Timsah, Egypt

Microbiology Insights ◽

10.4137/mbi.s6948 ◽

2011 ◽

Vol 4 ◽

pp. MBI.S6948 ◽

Cited By ~ 1

Author(s):

Magdy Bahgat

Keyword(s):

Bacterial Communities ◽

Bacterial Species ◽

Bacterial Community Composition ◽

Suez Canal ◽

Aquatic Environments ◽

The West ◽

Free Living ◽

Abundant Genus ◽

Living Bacteria ◽

Water Depths

Effect of pollution on diversity of attached and free-living bacteria in two contrasting stations, namely, Suez Canal and outlet of West Lagoon to Lake Timsah was investigated. Bacillus was the most abundant genus especially in West Lagoon station where higher organic agricultural and municipal loads was discharged. Bacterial species richness differed among water depths and was higher in subsurface samples. In Suez Canal more Gram negative populations were isolated. The possible influences of pollution in the West Lagoon station on the bacterial community composition were discussed.

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Effect of Gaseous Ozone on Listeria monocytogenes Planktonic Cells and Biofilm: An In Vitro Study

Foods ◽

10.3390/foods10071484 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1484

Author(s):

Felice Panebianco ◽

Selene Rubiola ◽

Francesco Chiesa ◽

Tiziana Civera ◽

Pierluigi Aldo Di Ciccio

Keyword(s):

Listeria Monocytogenes ◽

In Vitro Study ◽

Planktonic Cells ◽

Free Living ◽

Biofilm Inhibition ◽

Additional Tool ◽

Complete Inactivation ◽

Gaseous Ozone ◽

Food Borne

Among food-borne pathogens, Listeria monocytogenes continues to pose concerns to food business operators due to its capacity to form biofilm in processing environments. Ozone may be an eco-friendly technology to control microbial contaminations, but data concerning its effect on Listeria monocytogenes biofilm are still limited. In this study, the effect of gaseous ozone at 50 ppm on planktonic cells and biofilm of reference and food-related Listeria monocytogenes strains was evaluated. Ozone caused a reduction in microbial loads of 3.7 ± 0.4 and 3.9 ± 0.4 Log10 CFU/mL after 10 and 30 min, respectively. A complete inactivation of planktonic cells after 6 h of treatment was observed. Biofilm inhibition and eradication treatments (50 ppm, 6 h) resulted in a significant decrease of the biofilm biomass for 59% of the strains tested, whilst a slight dampening of live cell loads in the biofilm state was observed. In conclusion, gaseous ozone is not sufficient to completely counteract Listeria monocytogenes biofilm, but it may be useful as an additional tool to contrast Listeria monocytogenes free-living cells and to improve the existing sanitization procedures in food processing environments.

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A Five-Ingredient Nutritional Supplement and Home-Based Resistance Exercise Improve Lean Mass and Strength in Free-Living Elderly

Nutrients ◽

10.3390/nu12082391 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2391 ◽

Cited By ~ 1

Author(s):

Mats I. Nilsson ◽

Andrew Mikhail ◽

Lucy Lan ◽

Alessia Di Carlo ◽

Bethanie Hamilton ◽

...

Keyword(s):

Resistance Exercise ◽

Old Age ◽

Body Fat ◽

Lean Mass ◽

Daily Intake ◽

Protein Supplementation ◽

Muscle Quality ◽

Free Living ◽

Home Based ◽

And Function

Old age is associated with lower physical activity levels, suboptimal protein intake, and desensitization to anabolic stimuli, predisposing for age-related muscle loss (sarcopenia). Although resistance exercise (RE) and protein supplementation partially protect against sarcopenia under controlled conditions, the efficacy of home-based, unsupervised RE (HBRE) and multi-ingredient supplementation (MIS) is largely unknown. In this randomized, placebo-controlled and double-blind trial, we examined the effects of HBRE/MIS on muscle mass, strength, and function in free-living, older men. Thirty-two sedentary men underwent twelve weeks of home-based resistance band training (3 d/week), in combination with daily intake of a novel five-nutrient supplement (‘Muscle5’; M5, n = 16, 77.4 ± 2.8 y) containing whey, micellar casein, creatine, vitamin D, and omega-3 fatty acids, or an isocaloric/isonitrogenous placebo (PLA; n = 16, 74.4 ± 1.3 y), containing collagen and sunflower oil. Appendicular and total lean mass (ASM; +3%, TLM; +2%), lean mass to fat ratios (ASM/% body fat; +6%, TLM/% body fat; +5%), maximal strength (grip; +8%, leg press; +17%), and function (5-Times Sit-to-Stand time; −9%) were significantly improved in the M5 group following HBRE/MIS therapy (pre vs. post tests; p < 0.05). Fast-twitch muscle fiber cross-sectional areas of the quadriceps muscle were also significantly increased in the M5 group post intervention (Type IIa; +30.9%, Type IIx, +28.5%, p < 0.05). Sub-group analysis indicated even greater gains in total lean mass in sarcopenic individuals following HBRE/MIS therapy (TLM; +1.65 kg/+3.4%, p < 0.05). We conclude that the Muscle5 supplement is a safe, well-tolerated, and effective complement to low-intensity, home-based resistance exercise and improves lean mass, strength, and overall muscle quality in old age.

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