細菌の粘液作戦 鼻水が感染を促進するメカニズムが研究で明らかに(Bacteria’s mucus maneuvers: Study reveals how snot facilitates infection)

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2023-12-05 ペンシルベニア州立大学(PennState)

◆ペン・ステート大学の研究者による新しい研究によれば、風邪やインフルエンザの季節に増加する粘液が、細菌が免疫系に協調攻撃を仕掛けるのに利用されていることが示唆されました。
◆実験では、合成豚胃粘液や天然の牛子宮粘液、ポリビドンといった物質を使用し、粘液が水よりも厚い状態で細菌がより効果的に群れを成すことが観察されました。この結果は、細菌が粘液を利用して自己組織化し、感染を引き起こす方法を示し、これが細菌コロニーの抗生物質耐性を高める可能性があることを示唆しています。

<関連情報>

粘弾性により細菌の集団運動が促進される Viscoelasticity enhances collective motion of bacteria

Wentian Liao, Igor S Aranson
PNAS Nexus  Published:06 September 2023
DOI:https://doi.org/10.1093/pnasnexus/pgad291

Instant flow patterns of bacterial collective motion in mucus and PVP360. A) Schematics of the experimental setup. A free-standing film containing bacterial suspension in mucus is stretched between 4 movable wires. B) A schematic representation of motile bacteria (blue bodies with flagella) swimming in tunnels formed by mucin polymers (black tubes). The blue (brighter in grey-scale image representation) arrow indicates the swimming direction of mobile bacteria. The trapped bacteria are shown in red. C–E) Select frames illustrating instant flow patterns at the bottom of the film for different concentrations of mucin/PVP360; black arrows depict the direction and magnitude of bacterial flow, and colors show the vorticity w of bacterial flow. C) Instant flow pattern in 50 mg/mL mucin solution. D) Instant flow pattern in 200 mg/mL mucin solution. E) Instant flow pattern in 125 mg/mL PVP360 solution. The scale bar in all figures is 80 μm.

Abstract

Bacteria form human and animal microbiota. They are the leading causes of many infections and constitute an important class of active matter. Concentrated bacterial suspensions exhibit large-scale turbulent-like locomotion and swarming. While the collective behavior of bacteria in Newtonian fluids is relatively well understood, many fundamental questions remain open for complex fluids. Here, we report on the collective bacterial motion in a representative biological non-Newtonian viscoelastic environment exemplified by mucus. Experiments are performed with synthetic porcine gastric mucus, natural cow cervical mucus, and a Newtonian-like polymer solution. We have found that an increase in mucin concentration and, correspondingly, an increase in the suspension’s elasticity monotonously increases the length scale of collective bacterial locomotion. On the contrary, this length remains practically unchanged in Newtonian polymer solution in a wide range of concentrations. The experimental observations are supported by computational modeling. Our results provide insight into how viscoelasticity affects the spatiotemporal organization of bacterial active matter. They also expand our understanding of bacterial colonization of mucosal surfaces and the onset of antibiotic resistance due to swarming.

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