The Winogradsky column It is an apparatus used for the cultivation of different types of microorganisms. It was created by the Russian microbiologist Sergei Winogradsky. The growth of microorganisms will be stratified throughout the column.
Stratification is carried out based on the nutritional and environmental requirements of each group of organisms. For this, different types of nutrients and energy sources are supplied to the device..
The column is an enriched culture medium, where microorganisms of different groups will grow. After a maturation period that can last between several weeks and several months, these microorganisms will become available in specific microhabitats.
The microhabitats created will depend on the material used and the interrelationships between the organisms that develop.
Sergei Winogradsky (1856-1953), the creator of the column that bears his name, was a Russian microbiologist born in Kiev, now the capital of Ukraine. In addition to being a microbiologist, he was also an expert in ecology and soil studies.
His work with sulfur-dependent microorganisms and nitrogen biogeochemical processes gave him great renown. He described many new microorganisms, including the genera Nitrosomone Y Nitrobacter. He was also the discoverer of chemosynthesis.
Among the many recognitions received by this microbiologist are being named an honorary member of the Moscow Society of Natural Sciences..
He was also a member of the French Academy of Sciences. In 1935 he received the Leeuwenhoek Medal, a recognition awarded by the Royal Netherlands Academy of Arts and Sciences. He was invited by Louis Pasteur himself to be Head of Microbiology at the Pasteur Institute.
This device is nothing more than a glass or plastic cylinder containing different materials. The cylinder is filled to one third of its capacity with sludge or mud rich in organic matter.
Subsequently, cellulose and any other organic matter are added, which will serve as a source of organic carbon. As a source of sulfur, calcium sulfate is added and calcium carbonate is added to maintain the pH balance. The column is completed with water from a river, lake, well, etc..
The device must then be matured or incubated under sunlight or artificial light for a period of a few weeks to a few months. After that time, the spine stabilizes and well-defined microhabitats are established. Specific microorganisms will develop in each microhabitat according to their particular requirements..
The first microorganisms to colonize the column will begin to use the elements of the column and release gases and other substances that will inhibit or favor the development of other species..
As time passes, the activity of microorganisms and abiotic processes will produce chemical and environmental gradients throughout the column. Thanks to this, various niches for microbial growth will be generated..
By allowing this column to mature or incubate under sunlight or artificial light for weeks or months, gradients of oxygen and sulfides are formed..
This allows the development of a structured microbial ecosystem with a wide variety of microhabitats. In this way, all the processes that allow the maintenance of nutrient cycles take place in the column..
The upper area of the column, in contact with air, will be the richest in oxygen, which will slowly diffuse down.
At the same time, the products generated in the lower portion of the column, product of the degradation of cellulose and hydrogen sulfide, will diffuse vertically upwards..
The generation and diffusion of microbial metabolites, due to the various chemical gradients, originates a distribution of groups of organisms according to their requirements..
This distribution is similar to that established in nature. In this way, the Winogradsky column simulates the vertical microbial distribution found in lakes, lagoons, among others..
The lower portion of the column is completely devoid of oxygen and instead is rich in hydrogen sulfide. In this area, anaerobic bacteria such as Clostridium they degrade cellulose. As a result of this degradation, organic acids, alcohols and hydrogen are obtained..
The metabolites produced by Clostridium serve as a substrate for sulfate reducing species, for example Desulfovibrio. These, in turn, use sulfates or other forms of partially oxidized sulfur.
As a final product, they release hydrogen sulfide and are responsible for the high concentrations of this gas at the base of the column..
The presence of sulfate reducing bacteria on the column is shown as dark areas at the base of the column. Above the basal band, two shallow bands appear, with species using the hydrogen sulfide produced in the lower band. These two bands are dominated by anaerobic photosynthetic bacteria..
The most basal of these bands contains the green sulfur bacteria (Chlorobium). The next band is dominated by the purple sulfur bacteria of the genus Chromatium. Near these bands, iron-reducing bacteria appear, such as Gallionella, Bacillus or Pseudomonas.
A little further up the column, oxygen begins to appear, but in very low concentrations. This area is called microaerophilic.
Here, bacteria like Rhodospirillum Y Rhodopseudomonas they take advantage of the scarce oxygen available. Hydrogen sulfide inhibits the growth of these microaerophilic bacteria.
The aerobic zone is divided into two layers:
At the mud-water interface, bacteria of genera such as Beggiatoa Y Thiothrix. These bacteria can oxidize the sulfur coming from the lower layers.
The water column, for its part, is colonized by a great diversity of organisms, including cyanobacteria, fungi and diatoms..
-The Winogradsky column has various uses, among the most frequent are:
-Investigate microbial metabolic diversity.
-Study ecological sequences.
-Enrichment or isolation of new bacteria.
-To study the influences of environmental factors on the microbial community structure and dynamics and associated bacteriophages.