If you change the amino acid sequence, you change the protein's structure and therefore change its function. In the latter, building blocks are ordered by the enzymes that catalyze the polymerization reactions. Anaerobic Metabolism Anaerobic metabolism allows cells to grow in the absence of oxygen. Strict anaerobes are capable of only anaerobic metabolism. Some microbes reduce nitrate to nitrite.
Some microbes reduce nitrite further to nitrogen gas.
These organisms, called sulfur reducers , play a role in the sulfur cycle. Sulfate is reduced to hydrogen sulfide gas. B. Fermentation - This type of anaerobic metabolism uses no electron transport chain . Fermentation generates fewer ATP per molecule of substrate. Because many molecules of substrate must be metabolized to supply a cell's ATP requirements, the substrate must be in abundance in order for the microbe to grow.