Mimic the Conditions of Nature
Our understanding of the diversity of bacterial metabolism and its ecological importance got its start at the turn of the 20th century with the work of Sergei Winogradsky and Martinus Beijerinck. They developed techniques to grow different bacteria in the laboratory by mimicking or making use of natural substrates and conditions. Their work furthered that of Louis Pasteur showing there are a lot of different bacteria actively growing under anaerobic (very little to no oxygen) conditions, proved that carbon dioxide could be used to make organic C molecules (food) without the linkage to light energy capture by chlorophyll, and showed for the first time that some bacteria can capture energy from inorganic (lacking C) materials such as ammonium, sulfide, or reduced iron.
One of the enrichment techniques used by Winogradsky was the establishment of a standing artificial environment supported by exposure to light and applied chemical energy in the form of organic matter (also a C source) and sulfate/sulfide in order to establish a sulfur cycle. In a typical Winogradsky column, some mud and water are mixed with some sulfate and some complex carbon sources such as cellulose. Over time, gradients form with oxygen concentration decreasing from top to bottom and hydrogen sulfide concentration increasing from top to bottom. Different bacterial groups, if present in the original mud and water, grow best and form layers at the appropriate positions in the column with respect to oxygen, light, sulfide, and/or sulfate availability.
Hiram Genomics Store can customize the starting conditions for Winogradsky columns according to the experimental design from you and your students. We can provide, at a very reasonable price per column, as many Winogradsky columns as you need in a very easy to use 50 ml size. Each custom column will contain 20 ml of sterile sand and whatever sterile materials you want from a menu of choices – C sources (carbonate, cellulose, glucose, acetate), S sources (sulfate, thiosulfate, sulfide), N sources (ammonium), other nutrients (iron, manganese, phosphate). You provide 5-10 g of an environmental sample (mud, soil, gravel, etc.) and water (sterile or connected to your environmental sample) up to the 45 ml mark. Mix it all up, expose your columns to light (you choose the level of light exposure and intensity), and watch what happens.
The real beauty of Winogradsky columns are all the ways you can study them. You can make visual observations. You can take a whiff from time to time (carefully). You can use a sterile microbiology loop to take a sample for microscopy or for culturing on plates. You can take out a sample, or the whole column, and isolate metagenomic DNA to analyze using PCR or DNA sequencing. The experiment is totally in your hands.