Title of Lab: Winogradsky Column Construction

Title of Lab: Winogradsky Column Construction

Introduction

Purpose: togrow colonies of multi-hued microbes in a bottle in order to study ecological succession in a microbiological community

Question: Under which conditions do various color bacteria thrive? What type of bacteria are expected to grow?

Research / Background information: In the 1880's, a Russian microbiologist named Sergei Winogradsky discovered that water mud poured into a tall bottle and placed in the sun turned many different colors. Many kinds of bacteria live in mud. He found that by adding a few simple things, such as cheese or paper, he could control which colors appeared. During the process of decomposition, all the oxygen near the bottom of the container is used up. Red, orange and green bacteria that grow near the bottom of the column are less tolerant or completely intolerant of oxygen. They're photosynthetic; but they also get energy from hydrogen sulfide, the gas that smells like rotten eggs. These oxygen-phobic bacteria have crucial roles to play in the ecosystem. Some take part in the global sulfur cycle. Others convert nitrogen into forms needed by plants. Neither cows nor termites would enjoy their cellulose-based diets without the helpful bacteria in their guts that digest the cellulose for them. Some bacteria are decomposers that get nutrients by breaking down organic materials things like the paper or grass clippings. Other bacteria are photosynthetic and aerobic. Blue-green bacteria near the top of the mud column use light, carbon from carbon dioxide, and hydrogen from water to make carbohydrates and give off oxygen just like plants. The carbon dioxide they need is released when the decomposers break down the paper and grass clippings. The surface layer of the column may produce an aerobic liquid air biofilm (pellicle) that can be sampled by dipping a coverslip into the column and lifting a portion of the film from the water.

Procedure:

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