They calibrate our immune systems, ward off pathogenic bacteria, even affect our weight.

它们帮助我们调整免疫系统、抵御原菌、会影响到我们的体重。

A microorganism can be pathogenic, or not.

微物可以是致的，也可以不是。

It's the rare, pathogenic strains that can cause bloody diarrhea, kidney disease, or death.

导致出血性腹泻、肾或死亡的是极少数致株。

They also grew a batch of pathogenic E. coli bacteria, the kind that cause traveler's diarrhea.

们培养了一批致性大肠杆菌，这是导致旅行者腹泻的一种细菌。

YURKEVICH: The highly pathogenic avian influenza, or avian flu, is largely to blame.

高致性禽流行性感冒（禽流感）很大程度上来讲是罪魁祸首。

If as scientists have said it has only changed the pathogenic genes of AIDS without changing other genes.

如果说就像科学家说的，它只改变了艾滋的致基因，而没有改变其基因。

The 1918 virus instead could proliferate even in the absence of trypsin, making it more pathogenic than other viruses.

1918年的在没有胰蛋白酶的情况下也能增殖，这使得它比其更具致性。

After that they all got a dose of pathogenic E. coli — the strain behind last year's spinach outbreak.

再然后，所有老鼠都注射了致性大肠杆菌——去年菠菜事件后的菌株。

These kinds of cells need to go crawling around in our bodies in order to find invaders like pathogenic bacteria.

这些细胞在我们身体里四处爬行，以便发现诸如菌这样的入侵者。

To study how a pathogenic strain of E. coli behaves in this entire system, researchers had to build a replica.

为了研究大肠杆菌致菌株在整个系统的行为，研究人员不得不复制了系统。

For example, you may have heard of pathogenic bacteria like staph evolving antibiotic resistance.

例如，你可能听说过像金黄色葡萄球菌这样的原细菌进化出抗药性。

First is the PZ, or pathogenic zombies.

首先是 PZ， 即致僵尸。

But then there are some pathogenic forms of E. coli that can potentially kill you.

但有些致性的大肠杆菌可能会致命。

In other words you can make them more or less pathogenic or dangerous.

换句话说，你可以使它们或多或少具有致性或危险性。

They seem to be pathogenic or are they?

它们似乎具有致性，但真是如此吗？

The pathogenic defense force field is devastating.

这道原体防御力场太致命了。

It's not just about getting rid of any pathogenic bacteria.

这不仅仅是关于清除任何致细菌。

We need about 85% beneficial bacteria and about 15% pathogenic bacteria for the most part.

我们需要大约85%的有益细菌和大约15%的有害细菌。

Right. Then maybe we can stop them from becoming pathogenic in the first place.

没错。那么也许我们可以阻止它们从一开始就成为致菌。

When they did that, most of that pathogenic bacteria in the brain was no longer evident.

当们这么做的时候，大脑中的大部分致细菌就不再明显了。