Universal gas-vortex bioreactors present an entirely new type of devices.
Bioreactor is one of the main elements of different technological processes. Bioreactor in a microbiological process is intended for creation of the most optimal conditions for vital functions of the cultivated cells and microorganisms.
Microbial cells can survive intensive stirring and aeration. Mammalian, insect and plant cells are more sensitive to mechanical impacts irrespective of the cultivation method – in suspension or in immobilized state.
The bioreactor has a heterogeneous system of components consisting of cell suspension and gas. A system of this type should provide heat and mass transfer between the phases in order to create optimal conditions for the producer strain growth and biosynthesis of the desired product under conditions of sterility and the process efficiency.
Two methods of mixing are known and widely used in bioreactors:
- mixing with a mechanical device placed into the liquid phase, which makes the fluid move while rotating (a spoon in a glass of tea).
- mixing due to expulsion of the gas phase through the fluid (different airlift and bubble devices).
The disadvantage of bioreactors with a mechanical stirrer is the formation of highly turbulent and stagnation zones in the process of mixing, which makes nutrient medium supply to cells irregular. The same concerns the removal of metabolites.
The surface mass exchange through the phase boundary in the device is insufficient for most microorganisms and cell cultures.
Cultivated cells and microorganisms die because of the impact of shear tensions and microzones of local overheating, which appear at the ends of the stirrer blades.
In bioreactors with a mechanical stirrer, almost 70% of power is consumed for harmful overheating of culture fluid. In industrial bioreactors, it is necessary to remove this surplus heat, which requires additional expenditures. The energy (temperature) is introduced unevenly over the volume, which negatively influences the results of biotechnological processes with live organisms and enzymes existing and functioning in a strictly limited temperature range.
The disadvantage of airlift bioreactors is that they are not always suitable for cultures with high vital activity due to unintensive mixing (nutrient medium supply and removal of metabolites).
Floating air bubbles destroy sensitive cells as a result of a “collapse”.
Bioreactors of this type are characterized by abundant foaming, which does not allow the whole volume of the device to be used, and the use of a chemical defoamer decreases the quality of the end product and makes it more expensive.
It’s impossible to use viscous culture fluids in airlift bioreactors.
Most bioreactors used worldwide present a combination of these two types of devices.
The main disadvantages of these bioreactors are their limited application depending on the type of the producer strain used, scaling up problems when implementing the development in production, injury of cells and microorganisms at mixing, insufficient mass exchange, presence of turbulent and stagnation zones, high energy consumption, and poor characteristics at work with viscous media.
Despite the apparent diversity of the recommended bioreactors, they do not differ in the principle of operation and have the above disadvantages.
The development of new approaches in biotechnology and medicine, the growth of production of new drugs using mammalian cells, general increase in resource costs, higher requirements for the quality of obtained products and environmental friendliness of production, make it necessary to create new devices providing more effective performance of technological processes – universal bioreactors of the new generation.
The differences of gas-vortex bioreactors from existing types
Gas-vortex bioreactors differ from conventional devices by the fact that mixing is provided in them by air vortex (without a “stirrer” in the fluid), due to a pressure difference above the fluid surface and airflow friction force against its surface.
As a result, a well-organized three-dimensional motion with a vertical component is created in liquid medium. The absence of a “stirrer” in the fluid provides an energy-unintensive, mild, but very effective 3D-mixing of fluids including viscous ones, without foaming, water hammers, cavitations, highly turbulent and stagnation zones as well as high-temperature microzones.
Characteristics of the universal gas-vortex bioreactor
The universal gas-vortex bioreactor:
- provides mild, but very effective 3D-mixing of fluids
- is characterized by a high rate of mass exchange through the phase boundary, which solves the problem of cell injury by air bubbles;
- is characterized by low energy consumption of 0.1 Wt/L, which is several times lower than in bioreactors with a mechanical stirrer; this makes its use in large-scale production rather promising;
- is functioning without changing its characteristics at 10-90% filling of the volume, which allows removing intermediate “starting” bioreactors in industrial production;
- provides good mixing of viscous liquids and those with viscosity varying during the process;
- gas vortex is an effective defoamer.
The hydrodynamics of the bioreactor weakly depends on the level of fluid inside it, and the bioreactor can be easily scaled up.
Technical characteristics of universal gas-vortex bioreactors provide the following:
o successful cultivation of cells and microorganisms, which are poorly reproduced or cannot be reproduced in other types of bioreactors;
o using the bioreactor in processes involving viscous fluids or generating them during microbiological synthesis;
o substantial reduction of energy and resource expenditures when used in industrial production;
o reduction of the number of intermediate volume bioreactors in the technological chain;
o avoiding the use of a chemical defoamer that makes further processes of purification and end product manufacture much more complex and expensive;
o using gas-vortex bioreactors in different technological processes.
The main advantages of universal gas-vortex bioreactors
Entire universality is the possibility of effective use of the gas-vortex bioreactor in different technological processes.
Universality is the possibility of successful cultivation of practically all cell types (including highly sensitive ones) and microorganisms when used in microbiological processes.
Entire reproducibility (scalability) of laboratory results when implementing the developments in industry.
The effectiveness of using universal gas-vortex bioreactors in various research projects
Installation of universal gas-vortex bioreactors in laboratories of research institutes and other institutions working in the areas of microbiology and biotechnology allows us:
-to expand the range of tasks solved, including those associated with the country’s defensibility and biological safety;
-to reduce the number of procured laboratory bioreactors by purchasing a single universal gas-vortex bioreactor instead of several specialized ones for different types of cells and microorganisms. The device can function at 15-90% filling. This allows us to use a single bioreactor instead of a line of several bioreactors of different volumes. This is also important for saving culture media, which are often very expensive.
When implementing many laboratory developments in production, there emerges the problem of scaling up the obtained result i.e. the impossibility of reproducing the laboratory process at the industrial scale. It is very difficult and sometimes impossible to reproduce laboratory processes involving, first of all, sensitive cells (hybrid, embryonic and others). A major part of promising developments remains unimplemented due to the impossibility of reproducing obtained results with larger cultivation volumes. The reason is that the hydrodynamics of the mixing process at scaling up in the existing types of bioreactors changes greatly with a larger volume of the device.
The vortex method of stirring does not involve such problems.
Cultivation of different cultures in the universal gas-vortex bioreactor.
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The following cultures have been successfully cultivated in gas-vortex bioreactors:
Microorganisms: Salmonella gallinarum-pullorum 24 KCT, Pasteurella multocida suis #877, Erysipelothrix rhusiopathiae ÂÐ-2, E. coli #115, Leptospira ðomona), Salmonella Dublin, Salmonella th. Murium, Lactococcus lactis subsp. lactis, L.lactis subsp. diacetilactis and Lactobacillus acidophilus, Bacillus subtilis 26D Sacchoromyces cerevisiae M 437 y 116, Bacillus subtilis X-52-1, etc.
Cells: VERO, CEF, EL-4, BHK-2, cabbage moth IZD MB-0503, mouse myeloma Sp210-Ag l4P3, À4C5 (a hybrid of pig kidney cell and lymphocyte), human lymphocytes ÌÒ-4, human thymus cells (Ò-5), etc.
Fungi: Aspergillus awamori, Fusarium moniliforme 168, predacious fungi Duddingtonia flagrans, higher mushrooms – champignons, oyster mushrooms, shietaki, etc.
The modification of the gas-vortex bioreactor “Personal Doctor” was successfully used to cultivate human embryonic stem cells of hESM03 line in suspension and on carriers (a mononuclear fraction of donor bone marrow cells).
The effectiveness of using universal gas-vortex bioreactors in industry
Cost efficiency of production using universal gas-vortex bioreactors is achieved by:
• Minor initial investments as a result of:
- reducing the number of bioreactors in the technological chain;
- making communication pipelines simpler and shorter;
• reducing the total production costs (electric power, steam, detergents, area, wage bill);
• reducing the consumption of resources (water, electric power, etc.) and waste;
• universality of facilities i.e. the ability to work successfully with different types of producers;
• financial stability of the enterprise due to the possibility of fast and low cost modification or expansion of the product range.
The use of the gas-vortex bioreactor in industrial production allows us:
- to replace obsolete “roller”, “mattress” and “egg” technologies for manufacture of drugs (vaccines, etc.) with new ones ensuring compliance with GMP;
- to substantially reduce production costs.
The use of universal gas-vortex bioreactors allows for a quick switch of production from one producer strain to another. The enterprise can quickly respond to the latest developments in the area of practical biotechnology and change or expand the product range without large expenditures.
At present, industrial gas-vortex bioreactors are used in Russia and abroad to manufacture:
- vaccines and other drugs, blood substitutes (JSC “Protein Contour”, JSC “Gelenpol”, CJSC “Siberian Center for Pharmacology and Biotechnology”), etc.
- a broad range of veterinary vaccines, microbiological preparations for agriculture, insecticides and preparations for environmental protection (FSUE “Armavir Biofactory”, UE “"Vitebsk Biofactory” (Belarus), JSC “Bisolbi Inter”, JSC “Biotroph”, JSC “Agrovet”), etc.
- enzymatic hydrolysis (CJSC Biryuli) and other processes