科學60秒:狡猾的沙門氏菌
來源：滬江聽寫酷
2011-05-22 00:06
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Last month's salmonella outbreak got over 1,500 people sick. And one reason salmonella may be such a heavy hitter is that it actually ___1___ our immune response for its own benefit. That's according to a study in the journal Nature.
Bacteria in our gut ___2___ things like sugars and fatty acids, which they can break down either through respiration or fermentation. Respiration provides a bigger energy kick. But it requires oxygen, which is ___3___ in the gut. So most bacteria go the fermentation route.
Except salmonella. Because it’s adapted to use the respiration route. Not with oxygen, but via a sulfur compound—something most bacteria can't do.
The insidious thing is that the sulfur compound the salmonella ___4___ is a by-product of the attack our white blood cells launch against the invaders. So by protecting ourselves, we're also ensuring that salmonella stay well-fed. Because a more inflamed gut allows salmonella bacteria to outcompete good bacteria, and explode in numbers. And the little buggers also use our attempts to ___5___ vomiting and diarrhea. Those are both excellent ways for the bugs to get to their next victims.
Last month's salmonella outbreak got over 1,500 people sick. And one reason salmonella may be such a heavy hitter is that it actually ___1___ our immune response for its own benefit. That's according to a study in the journal Nature.
Bacteria in our gut ___2___ things like sugars and fatty acids, which they can break down either through respiration or fermentation. Respiration provides a bigger energy kick. But it requires oxygen, which is ___3___ in the gut. So most bacteria go the fermentation route.
Except salmonella. Because it’s adapted to use the respiration route. Not with oxygen, but via a sulfur compound—something most bacteria can't do.
The insidious thing is that the sulfur compound the salmonella ___4___ is a by-product of the attack our white blood cells launch against the invaders. So by protecting ourselves, we're also ensuring that salmonella stay well-fed. Because a more inflamed gut allows salmonella bacteria to outcompete good bacteria, and explode in numbers. And the little buggers also use our attempts to ___5___ vomiting and diarrhea. Those are both excellent ways for the bugs to get to their next victims.
hijacks
gobble up
sparse
feast on
expel them with
上個月沙門氏菌大爆發(fā)撂倒了1500多人。沙門氏菌威力如此強大的原因之一可能是人體的免疫反應被它利用了。這是刊登在《自然》雜志上的一項研究得出的結果。
我們內(nèi)臟里的細菌會吞噬糖類和脂肪酸一類的物質(zhì)，它們通過呼吸作用和發(fā)酵作用可以分解此類物質(zhì)。呼吸作用能夠為細菌提供更大的能量，但這個過程需要氧，而內(nèi)臟里氧氣稀薄，因此大多數(shù)細菌都是利用發(fā)酵作用來分解上述物質(zhì)的。
不過，沙門氏菌就是個例外了。因為它能通過呼吸作用分解糖類和脂肪酸。不過在這過程中不是利用的氧，而是利用一種硫化物，其他大多數(shù)細菌是沒有這種能力的。
令人無奈的是，沙門氏菌的得力助手——硫化物是人體內(nèi)白細胞攻擊入侵病毒時產(chǎn)生的副產(chǎn)品。也就是說，我們在保護自身的同時，沙門氏菌也得到了很好的滋養(yǎng)。因為內(nèi)臟炎癥越嚴重，沙門氏菌就能戰(zhàn)勝有益細菌，并迅猛增殖。人們嘔吐、腹瀉會把沙門氏菌排出體外，不過這一點也被它們利用了，因為這是它們感染下一個目標的絕佳途徑。