虽然胃不像心脏那样令人振奋，也不像大脑那样神秘，但它同样令人印象深刻：肌肉袋里充满了强大的酸，可以溶解金属——但它不会消化器官本身。

The stomach protects itself from its own acid with a coating of mucus, a tactic that doesn’t always work against the ulcer- and cancer-causing 幽门螺杆菌, the only bacterium known to colonize that harsh environment. 幽门螺旋杆菌 以某种方式在酸中存活下来，游过黏液层，感染胃细胞。 An estimated 50 percent of humans harbor 幽门螺旋杆菌 in their gut, but only some of them develop ulcers or stomach cancer. So understanding how 幽门螺旋杆菌 survives here is key to understanding those diseases.

罗摩Bansil他是美国艺术与科学学院（College of Arts & Sciences）的物理学教授，新濠影汇线上赌场研究胃粘液已有20多年，他发现了使这种细菌占优势的两个因素：它分泌的化学物质和它的游泳技能。 这两点对它的成功至关重要。

Bansil, whose work is funded by the 国家科学基金会, became curious about stomach mucus in the late 1980s. 她说：“当时的问题是，胃每天产生近半加仑的胃液，胃液是酸性的，可以消化指甲，那为什么胃不消化呢？” 新濠影汇线上赌场研究人员怀疑，薄薄的一层粘液保护胃免受这种酸的侵害，但没有人确切知道它是如何起作用的。 Bansil的新濠影汇线上赌场研究领域是凝胶和凝胶化，他开始新濠影汇线上赌场研究纯化的蛋白粘蛋白，它使胃粘液具有凝胶化的能力。 在这项早期工作中，她和她的同事们发现，它只有在pH值低于4的极端酸性条件下才会凝固。

Later, she turned her attention to 幽门螺旋杆菌. 她说：“我决定试着看看这种细菌是如何通过的，因为这一层可能是凝胶状的，或者至少肯定是非常粘稠的，就像柔软的牙膏或凡士林一样。”

一些新濠影汇线上赌场研究人员曾假设，这种螺旋状的细菌像开瓶器一样钻穿厚厚的黏液。 But in lab experiments, Bansil and her colleagues found, surprisingly, that 幽门螺旋杆菌, which propels itself with rotating flagella, couldn’t swim through a gel at all.

胃粘液则不是这样。 There, 幽门螺旋杆菌 secretes an enzyme called urease, which breaks down urea in the stomach into carbon dioxide and ammonia, giving the smell of ammonia to the breath of infected people. 氨，一种碱，与胃粘液反应，提高其pH值并使其液化。 班西尔说：“它使凝胶脱胶，这种可逆的凝胶化是让这种细菌通过的关键。”

If 幽门螺旋杆菌’s corkscrew shape didn’t help it drill through mucus, wondered Bansil and her colleagues, why did it have that shape? Another spiral-shaped bacterium called 空肠弯曲杆菌 (a common cause of food poisoning) is able to colonize the upper part of the small intestine, so the shape must be important for something.

Many assumed that the corkscrew-shaped body increased 幽门螺旋杆菌’s swimming speed in general, because corkscrew shapes produce thrust when they spin. Previous experiments by other groups supported this, finding that spiral-shaped 幽门螺杆菌 swam two to three times faster than rod-shaped 大肠杆菌. “但这不是一个好的比较，因为你实际上是在比较两种不同的生物，”Bansil说。 She collaborated with Nina Salama, a microbiologist at the Fred Hutchinson Cancer 新濠影汇线上赌场研究 Center in Seattle who had bred mutant 幽门螺旋杆菌, the same as the original but rod-shaped.

然后，他们拍摄了数百只鲨鱼在黏液和培养液中游泳的过程，看看哪只游得更快。 通过对比视频，他们发现，螺旋形细菌的平均速度比杆状细菌快10%到15%。

Maira Constantino （GRS ' 17）是Bansil实验室的博士候选人，她想通过拍摄单个细菌的运动和形状来进一步分析。 通过以每秒200帧的高速拍摄视频，她能够记录下单个细菌的速度、旋转和体型。 她和她的同事们发现，这两种细菌在游动时都在旋转，大约每秒10到15个体长——“相当不错的步伐”，但螺旋游得更快一些。 To understand why, Bansil and Constantino sent the data to colleagues in the mechanical engineering department at the University of Utah, who used them to build a theoretical model of 幽门螺旋杆菌 swimming. 犹他大学的科学家们发现，鞭毛多对速度的影响大于体型； 螺旋形状最多贡献了细菌推进力的15%，证实了科学家们之前的发现。 班西尔说：“15%的差异看起来不是很大，但从长远来看，这可能是一个足够的优势，螺旋形的将胜过杆状的。”

The results were published in November 2016 in 科学的进步. Bansil and her colleagues are now studying 幽门螺旋杆菌 from a cancer patient, as well as the patient’s stomach mucus, looking for clues in the specific interaction of the bacterium with mucin.

Bansil的工作可能会在另一个科学领域被证明是有用的：药物输送。 “许多药物无法通过黏液。 只有非常小的药物才能通过，或者那些能分解粘液的药物。” It is not difficult to render 幽门螺旋杆菌 harmless by genetic manipulations, and if it can be loaded like a capsule, with, say, a chemotherapy drug, the bacterium could then use its innate ability to get across mucus and deliver it where it’s needed. 班西尔说：“这可能是一种非常聪明的口服靶向药物的方法。”