Prescott's Microbiology 8th Edition by Joanne Willey, Linda Sherwood, Christopher J. Woolverton, Lansing Prescott, John Harley, Donald Klein

Exercise 2

How did Winogradsky and Beijerinck contribute to the study of microbial ecology? What new culturing techniques did they develop in their studies?

Step 1 of 2

Microbial ecology is the study of how communities of microorganisms interact with each other. Winogradsky showed that soil bacteria played an important role in the cycling of inorganic and organic nutrients. Different types of soil bacteria could utilize iron, sulfur, and ammonia as energy sources. Bacteria are also capable of fixing carbon dioxide to create their own organic material much like plants do.

Beijerinck is known for isolating Rhizobium, which is an important bacterium that lives on the roots of plants. Rhizobium is capable of fixing nitrogen and is an important part of the nitrogen cycle. Nitrogen fixation is ability to convert nitrogen gas (N₂) into ammonia. Most organisms, like humans and even most bacteria, are unable to do this and require a nitrogen supplement to grow.

Beijerinck also isolated sulfate-reducing bacteria. Sulfate-reducing bacteria tend to be anaerobic (prefers no oxygen environments) and are reduce sulfate to hydrogen sulfide. Sulfate is common in water or sediment that has lots of decaying organic material (for example: - a swamp or marsh.) The stinky smell is result from the hydrogen sulfide end product that is released by these bacteria.