Winogradsky column

The Winogradsky column is used for the isolation of phototrophic green and purple bacteria and other anaerobes. It is named after the Russian microbiologist Sergei Nikolayevich Winogradski. This she developed in the eighties of the 19th century in order to investigate soil organisms can.

The column thus represents an anaerobic (without the presence of atmospheric oxygen) ecosystem in miniature format and can also be a long time source for many species of prokaryotes are involved in the nutrient cycle. The column was applied in the enrichment of a variety of aerobic and anaerobic prokaryotes. The advantage of the column is the one in the ready availability of inocula (see inoculation), but also that it can be selectively enriched with compounds, their decomposition processes are to be studied. It can thus be " picked " microorganisms which are capable of degrading the substrate under investigation.

A further advantage of the column is that it is similar to a natural habitat many more, as a liquid culture medium which is inoculated with a sample. Thus, a variety of physiological types of microorganisms are observed, whereas the slower-growing would displace rapidly in an enrichment culture faster growing species.

Production

Preparing a Winogradsky column is carried out in a glass cylinder. This will be filled to ~ 1/3 with mud, which is rich in organic substances and also contains sulfides. First, the sludge carbon substrates are added. In the past there were also various organic additives used. Among other things, hay, chopped newsprint, sawdust, crushed leaves or root material, ground beef, hard boiled eggs and some dead animals. The reports also the addition of calcium carbonate (CaCO3 ) and calcium sulfate ( CaSO4 ) which serve as a buffer in the mud as well as the sulfate source. The sludge is pressed firmly into the cylinder, it must be ensured that no air is trapped oxygen. Then the sludge is mixed with water overlaid ( from pond, lake or ditch ) and sealed with aluminum foil or, as seen in the picture with parafilm. The cylinder is placed into the light in order to ensure an adequate supply of sunlight. However, it is important to ensure that it is not exposed to excessive radiation.

Typically in the Winogradsky column develops a mixture containing many types of microorganisms. At the top of the rapidly forming cyanobacteria and algae. Since these oxygen ( O2) to produce, this zone is rapidly oxic. Fermentative decomposition processes that occur in the mud, leading to the production of organic acids, hydrogen ( H2) and alcohols. These are suitable substrates for sulphate-reducing bacteria. As a result of sulfide production appear on the side facing the light green and purple spots. The green spots consist of green sulfur bacteria whose development often takes place in the lower layers of the column near the sulfide source. The purple spots that consist of purple sulfur bacteria form increased in the upper layers. This finding can be explained by a different sulfide tolerance of green and purple bacteria.

At the interface of water to sludge is (usually) to detect a significant turbidity and coloring of the water due to the growth of purple sulfur bacteria and some other bacteria. Using a pipette, the sample can be taken from phototrophic bacteria. This is for the little colored water or mud. With these sample enrichment media ( culture media ) can be inoculated.

Anaerobic phototrophic bacteria

In the Winogradsky column are found in typically four different families of anaerobic phototrophic bacteria. Firstly, the order of the Chlorobiales ( green bacteria). Here are the family of Chlorobiaceae ( green sulfur bacteria) with the species Chlorobium limicola and the family of Chloroflexaceae ( Chloroflexus group) to name the species Chloroflexus aurantiacus. Secondly, the order of the Rhodospirillales ( purple bacteria ) with the families of Chromatiaceae ( purple sulfur bacteria ) and the family of Rhodospirillaceae ( purple non-sulfur bacteria). These include the species Chromatium vinosum rubrum and Rhodospirillum.