Scientists from the RAS Institute of Microbiology named after S. Vinogradsky, in cooperation with their European colleagues, have collected microbes capable of producing methane by anaerobic processing in bioreactors. These microorganisms live on the bottom of Central Asian and Altai region lakes. In Germany plans are underway to build an experimental industrial plant designed for this technology thought to become a breakthrough in the development of renewable power engineering. This is the subject dealt with by journalist Alexei Shabelsky on the pages of the electronic edition of Science and Technology of Russia-STRF.ru with reference to a related publication in the American Journal of Biotechnology.

Methane-generating microorganisms have been long in the focus of attention of biotechnologists due to the great role they play in the anaerobic (oxygen-free) digestion of industrial and household waste waters. In fact, they generate a biogas from effluents-it can replace the expensive natural gas; in addition, its resources are renewable. Although methane is already produced commercially, it cannot fully replace the gas extracted from industrial wells, as waste household waters contain a very small amount of carbon-rich substances. Therefore, scientists are out to process the biomass thus produced into methane.

An international group of authors from Germany (Institute of Genomic Studies and Systemic Biology, Max Planck Institute of Marine Microbiology), the Netherlands (Delft Technological University) and Russia (Laboratory of Ecology and Geochemical Activity of Microorganisms of the RAS Microbiology Institute named after S. Vinogradsky) has been long studying the vital activity of microbes in extreme conditions, in particular, in saturated soda solutions. In these media "protons are a basis of life in neutral conditions which, partially or fully, are replaced by sodium ions",-explained Dmitry Sorokin, Dr. Sc. (Biol.), the project's participant from Russia, a leading research fellow of the RAS Microbiology Institute, in his STRF.ru interview-The fact is that in strongly alkaline media there is an insufficient number of hydrogen ions (protons) required for the vital activity of the cell. Therefore, it has to build its metabolism and use "what it has". In case of soda solutions, we have sodium ions. In order to actively function in non-standard conditions, microorganisms require special enzymes and cellular mechanisms, absent in neutrophils (organisms, living in "ordinary", neutral media). So, the cell starts using sodium ions. In this case an additional and rather useful effect will be to include such organisms into technological processes taking place at high pH and salinity."

The researchers studied an opportunity of the use of microorganisms of benthic sediments from hypersaline soils of soda lakes of Central Asia as a reaction medium for alkaline bioreactors for methane production through anaerobic processing. They combined measurements of the efficiency of methane production from various substrates with genetic characteristics of the methanogene population (microorganisms producing methane in their vital activity) by means of a special marker gene mcrA.

Next, benthic sediments were taken out from several saline soil sodium lakes of the Kulunda steppe in Altai. For more than a year microbes isolated from these samples were kept at a temperature of 4 °C under a definite pressure in a glass container in an inert atmosphere. Then they were added to a substrate (with methanol, acetate or hydrogen used for this purpose), all this allowed to stand in darkness for 10 days. Later on, by gas chromatography the amount of produced methane was determined. The highest biogas concentration was found to be present in a substrate of methanol (methyl alcohol) at pH 10 (i.e. in a strongly alkaline medium) in the uni-molar solution of salt. Thus, methyl alcohol is the most effective substrate for bioreactors.

Proceeding from mcrA-labeled microorganisms, the scientists have established: in benthic sediments of Altai lakes there exist mainly 4 types of methanogenic microorganisms. None of them was ever mentioned in the previous works of other authors. That is, microorganisms from the bottom of lakes of Kulunda steppes were found to be unique. According to specialists, it is possible to start biological production of renewable energy resources on this basis. Besides, such microbes can cleanse highly alkaline gutters formed in the process of gas- and oil-refining in the pulp and paper, and textile industries.

Scientists from different countries intend to work on applied aspects independently. According to Sorokin, in Russia it will take several years until the research results reach the industry. First, it is necessary to create a methane-producing model to be tested in laboratory bioreactors. And if the result is promising, a pilot plant will be built for large-scale production.

German biotechnologists participating in this project, have great plans for creating commercial bioreactors. All the more so, since the German government has decided in perspective to scale down the use of non-renewable energy resources (in particular, ordinary natural gas) and is regularly financing the program of producing biogas from various agricultural wastes.

A. Shabelsky, "Microbes of Altai Lakes Will Be Used to Produce Methane".-Electronic journal "Science and Technologies of Russia--STRF.ru", November 2, 2012

Illustration supplied by Dmitry Sorokin

Prepared by Sergei MAKAROV