Scientists Revived Soviet-era Technology

15:58, May 17, 2021

With this technology, bacteria are grown for protein feed and additives

A Russian research and production team, which includes employees of UrFU, revived the technology of growing methanotrophic bacteria (haprin), which was developed in the Soviet Union. This technology produces highly concentrated protein feed (bioprotein) from bacteria for farm animals and fish.

"The first bioprotein production projects were launched back in the 1970s and 1980s in the USSR, Europe, and the United States. In the West the development continued, but in Russia in 1994 the research and production stopped. Now the technology is being revived. We managed to collect data, check the efficiency of solutions developed by German and Soviet scientists at that time, select the most optimal variants of the unit operation and increase the safety of the bioreactor," says Irina Nizovtseva, the Director of Science of the Bioprotein Consortium and a researcher of the Laboratory of Multi-Scale Mathematical Modeling at the UrFU.

Mathematicians from the UrFU conducted calculations for an ejector-type bioreactor. Using mathematical models and supercomputers, they predicted the behavior of the medium in the reactor.

"We had the task of selecting the mode of operation of the mixer, determining the optimal modes, gas/liquid ratios in a way that would ensure the most efficient mixing of water, gas, and salts. For example, to avoid large methane bubbles and, accordingly, the probability of explosion. This is not only a question of economic efficiency, reactor safety, but also the life of bacteria, so they don't get sick and reproduce properly," explains Ilya Starodumov, junior researcher at the Ural Federal University's Laboratory of Multi-Scale Mathematical Modeling.

The essence of the technology is that bacteria feed on methane, oxygen and salts dissolved in water, multiply, and form biomass. The biomass is then dried and added to feed in the form of pellets. One of the main problems is to convert methane from a gas to a liquid state and let the bacteria eat it. Methane is a hydrophobic gas, so dissolving it in water is not easy. Classic fermenters are not up to the task. Special reactors are needed. All the technological differences that exist today between developers are related to the design of the bioreactor and the technology of growing bacteria in it. The characteristics at which methane and oxygen from the gas phase pass into the liquid phase, bioreactor design and technological process setup determine the efficiency and energy intensity of the process, therefore, affect the cost of the finished product, its demand and competitiveness on the market.

"The difficulty of growing bacteria is that you have to simultaneously dissolve methane and oxygen to feed the bacteria, and remove carbon dioxide. Since bacteria are alive, it is important to maintain the same temperature regime - about 42 degrees - throughout the entire reactor. You cannot just take all this and scale it up. The process works differently in industrial large-scale plants than it does in the laboratory. Many factors have to be calculated and measured not in real conditions - that is expensive, time consuming, and dangerous - but with the help of modeling. This is what we do," explains Ilya Starodumov.

In addition, scientists are working on tuning the control of the bioreactor with the help of neural networks. Trained algorithms must continuously calculate and predict the hydrodynamics of the process and calculate safety parameters (microbiological and physical). This helps minimize the human factor, ensure explosion and fire safety, and reduce energy consumption for dissolving oxygen and methane. Not only mathematicians from UrFU, but also geneticists, microbiologists, physicists, and technologists from other research centers are working on improving the technology.

"At the first stage, we worked together with the Federal Research Center for Biotechnology of the Russian Academy of Sciences, the Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, and the company Tesis. We solved the issue of scaling, checked that the technology works, and worked under the optimization of the mixing process. Currently we face the task of formulating proposals for modernization of technological solutions," explains Irina Nizovtseva.

Reference

Methanotrophic bacteria were first discovered in soil in 1905. They live in subglacial lakes of Antarctica, in sediments of seas, lakes, ponds, in "mud volcanoes", in tectonically active zones of Baikal; they "feed" on methane. Biomass of methanotrophic bacteria contains about 70-75% protein; its amino acid composition (contains lysine, methionine, cystine, tryptophan, arginine, thiamine, riboflavine) is close to that of milk and easily assimilated. In the future, methanotrophic bacteria may become a quality protein supplement to food not only for farm animals and fish, but also for humans. Today, protein from soy and fish meal is mostly added to animal and fish food.