Helicobacter pylori moves through mucus by reducing mucin viscoelasticity

Abstract

The ulcer-causing gastric pathogen Helicobacter pylori is the only bacterium known to colonize the harsh acidic environment of the human stomach. H. pylori survives in acidic conditions by producing urease, which catalyzes hydrolysis of urea to yield ammonia thus elevating the pH of its environment. However, the manner in which H. pylori is able to swim through the viscoelastic mucus gel that coats the stomach wall remains poorly understood. Previous rheology studies on gastric mucin, the key viscoelastic component of gastric mucus, indicate that the rheology of this material is pH dependent, transitioning from a viscous solution at neutral pH to a gel in acidic conditions. Bulk rheology measurements on porcine gastric mucin (PGM) show that pH elevation by H. pylori induces a dramatic decrease in viscoelastic moduli. Microscopy studies of the motility of H. pylori in gastric mucin at acidic and neutral pH in the absence of urea show that the bacteria swim freely at high pH, and are strongly constrained at low pH. By using two-photon fluorescence microscopy to image the bacterial motility in an initially low pH mucin gel with urea present we show that the gain of translational motility by bacteria is directly correlated with a rise in pH indicated by 2 ,7 -Bis-(2-Carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF), a pH sensitive fluorescent dye. This study indicates that the helicoidal-shaped H. pylori does not bore its way through the mucus gel like a screw through a cork as has previously been suggested, but instead achieves motility by altering the rheological properties of its environment.H. pylori ͉ bacterial motility ͉ rheology ͉ pH ͉ gelation

Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold

“…Estimates for the torque of the enteric motor ranges from ∼1,300 to ∼2,000 pN·nm (20,21). The e-proteobacterium H. pylori has been estimated to swim with torque of 3,600 pN·nm (22), and spirochetes are capable of swimming with 4,000 pN·nm of torque (21,23). Sodium-driven motor torques in Vibrio spp.…”

Unlocking the secrets of multi-flagellated propulsion: drawing insights fromTritrichomonas foetus

“…While it was necessary to model T. foetus as a prolate ellipsoid, because irregular shapes are too complex, in actuality an undulating membrane wraps around its body from the anterior to posterior region, and it is possible that this structure generates a reduction in drag upon spinning. Further, owing to the motion and position of the flagella and undulating membrane during linear swimming in T. foetus, it is reasonable to hypothesize that the viscoelastic properties of the localized fluid could be altered as a result of interactions occurring at this interface, as reported for other microorganisms [67]. In the work done by Spagnolie et al [65], it was shown that viscoelasticity can either increase or decrease both the swimming speed and/or swimming efficiency of helical bodies depending on geometry, fluid properties and rotation rate.…”

Food Additive P-80 Impacts Mouse Gut Microbiota Promoting Intestinal Inflammation, Obesity and Liver Dysfunction

“…Colonic expression of LCN-2 mRNA was measured by qRT-PCR and demonstrated a significant increase relative to control mice ( Figure 3E). Faecal LCN-2 is a sensitive and broadly dynamic marker of intestinal inflammation in mice [25]. P-80 fed mice showed elevated fecal LCN-2 levels ( Figure 3F) after four weeks compared to control mice.…”