Caenorhabditis elegans: a model to monitor bacterial air quality

Abstract

BackgroundLow environmental air quality is a significant cause of mortality and morbidity and this question is now emerging as a main concern of governmental authorities. Airborne pollution results from the combination of chemicals, fine particles, and micro-organisms quantitatively or qualitatively dangerous for health or for the environment. Increasing regulations and limitations for outdoor air quality have been decreed in regards to chemicals and particles contrary to micro-organisms. Indeed, pertinent and reliable tests to evaluate this biohazard are scarce. In this work, our purpose was to evaluate the Caenorhaditis elegans killing test, a model considered as an equivalent to the mouse acute toxicity test in pharmaceutical industry, in order to monitor air bacterial quality.FindingsThe present study investigates the bacterial population in dust clouds generated during crop ship loading in harbor installations (Rouen harbor, Normandy, France). With a biocollector, airborne bacteria were impacted onto the surface of agar medium. After incubation, a replicate of the colonies on a fresh agar medium was done using a velvet. All the replicated colonies were pooled creating the "Total Air Sample". Meanwhile, all the colonies on the original plate were isolated. Among which, five representative bacterial strains were chosen. The virulence of these representatives was compared to that of the "Total Air Sample" using the Caenorhaditis elegans killing test. The survival kinetic of nematodes fed with the "Total Air Sample" is consistent with the kinetics obtained using the five different representatives strains.ConclusionsBacterial air quality can now be monitored in a one shot test using the Caenorhaditis elegans killing test.

Gamma-aminobutyric acid acts as a specific virulence regulator in Pseudomonas aeruginosa

“…considered to be an equivalent of the acute mouse toxicity test (Williams et al, 2000) and has been adapted to compare the virulence of environmental bacteria (Duclairoir Poc et al, 2011). In addition, whereas the 'fast-killing' test gives information on the contribution of diffusible virulence factors in the lethal activity of the bacterium, the 'slow-killing' test reveals global variations of virulence, including those that are due to direct contact with the bacterial surface (Aballay & Ausubel, 2002).…”

“…In the 'fast-killing' test, worms are killed by bacterial diffusible toxins whose secretion is stimulated by use of a high-osmolarity medium (Aballay & Ausubel, 2002). In the 'slow-killing' test, worms are killed after ingestion of the bacteria (Duclairoir Poc et al, 2011). Pathogen lawns used for C. elegans survival assays were prepared by spreading 50 ml control or GABA-treated P. aeruginosa PAO1 (OD 580 1) (obtained as previously described) on 35 mm peptone-glucose-sorbitol (PGS: 1 % BactoPeptone; 1 % NaCl, 1 % glucose, 0.15 M sorbitol, 1.7 % Bacto-Agar) conditioned Petri dishes for 'fast-killing' evaluation or on 35 mm nematode growth medium (NGM: 3 g NaCl, 2.5 g peptone, 17 g agar, 5 mg cholesterol, 1 ml 1 M CaCl 2 , 1 ml 1 M MgSO 4 , 25 ml 1 M KH 2 PO 4 , H 2 O to 1 l) conditioned Petri dishes supplemented with 0.05 mg 5-fluoro-29-deoxyuridine ml 21 for 'slow-killing' experiments.…”

“…The effect of GABA on bacterial virulence was studied by using two models, i.e. cultured rat glial cells to evaluate the cytotoxic activity of the bacteria in nerve cells (Picot et al, 2001) and the nematode Caenorhabditis elegans, a metazoan model used to assess the general virulence of human pathogens and environmental bacteria (Duclairoir Poc et al, 2011). Preliminary controls showed that exposure of P. aeruginosa PAO1 to GABA (0.01 mM) during the whole growth phase, or at the beginning of the stationary phase, did not modify the growth kinetics of the bacterium.…”

Air Pollution Alters Caenorhabditis elegans Development and Lifespan: Responses to Traffic-Related Nanoparticulate Matter

“…While there are limitations such as lack of specific organ equivalents, a smaller immune response system, and large differences in overall lifespan, C. elegans allows medium-throughput whole organism-level assays with multiple endpoints (eg, development, reproduction, feeding, lifespan, locomotion) (15). Worms have been used to assess the toxicity of terrestrial environmental samples (eg, soils, sludge, river sediments (17,18), pesticides (eg, Glyphosate, Paraquat, Endosulfan and Dichlorvos for neurotoxicity, DNA damage, sterility and embryonic lethality) (19), metal toxicity (eg, Ag, Cd, Pb, Fe), lifespan, fertility, growth (20), nanoparticles (21), drugs (22), toxins (eg, nicotine) (23–25), as well as other bioreactive molecules including NaAsO 2 , NaF, caffeine, and DMSO (26). While airborne bacteria have been tested in C. elegans (17), its responses to TRAP have not been studied.…”

“…Worms have been used to assess the toxicity of terrestrial environmental samples (eg, soils, sludge, river sediments (17,18), pesticides (eg, Glyphosate, Paraquat, Endosulfan and Dichlorvos for neurotoxicity, DNA damage, sterility and embryonic lethality) (19), metal toxicity (eg, Ag, Cd, Pb, Fe), lifespan, fertility, growth (20), nanoparticles (21), drugs (22), toxins (eg, nicotine) (23–25), as well as other bioreactive molecules including NaAsO 2 , NaF, caffeine, and DMSO (26). While airborne bacteria have been tested in C. elegans (17), its responses to TRAP have not been studied. Considering the usefulness of C. elegans in diverse toxicology models, this study introduces C. elegans as a multicellular model organism for air pollution toxicity.…”