Then, they manipulated the carbon and nitrogen sources they gave these bacteria to see which maximized biohydrogen production.

然后，他们操纵给这些细菌的碳和氮源，看看哪个能最大限度地提高生物氢的产量。

The problem with the nitrates is, though many plants can use nitrates as a nitrogen source, but nitrogen cannot bind to the soil.

硝酸盐的问题是，虽然很多植物都可以将硝酸盐用做氮元素来源，但是氮不会被锁在土壤中。

In the end, two compounds common in wastewater, malic acid as a carbon source and sodium glutamate as a nitrogen source, produced the most hydrogen while minimizing carbon dioxide emissions.

最后，废水中常见的两种化合物，作为碳源的苹果酸和作为氮源的谷氨酸钠，产生了最多的氢，同时最大限度地减少了二氧化碳的排放。