Bacteria refer to the regnum of prokaryotes (Sundararaj, Mudaliar, Anthoniraj, Kannan, Muthukaruppan). For the current moment, it accounts for more than ten thousand kinds of bacteria. The bacterium is recognized as one of the most ancient of living organisms, arising about 3.9 – 3.5 billion years ago. Bacteria have the substantial variation in the ways of metamorphic and energetic metabolism. Thus, autotrophs can synthesize all necessary organic molecules from non-organic compounds, whereas heterotrophs demand active organic compounds to transform them. The biggest degree of heterotrophs belongs to intracellular parasites. They are called saprophytes (Sundararaj, Mudaliar, Anthoniraj, Kannan, Muthukaruppan) and can use the active organic compounds either from the dead organisms or by swallowing this substance from the atmosphere. As for the ways of getting energy, there is the majority of them: fermentation, respiration, and photosynthesis. However, the scientists discovered some rare forms of bacteria which could use the power of the disintegration of uranium ore.
Despite the controversial issue regarding the attitude of people to bacteria, microbes play a crucial role in nature and human activity. Many bacteria participate in the soil formation as well as decomposition of dead fossils of animals and plants using assimilation of atmospheric nitrogen. Many bacteria take part in maintaining the level of oxygen and carbon dioxide on the Earth.
People have learned to apply the bacteria in agriculture, industry, and medicine since ancient times. Thus, in BC times Romans could extract copper from pit waters using the microbe leaching. Nowadays, people apply the same method to obtain gold, copper, uranium, manganese and other metals. The growing interest in the microbic metabolism is also explained by the way to find the possible alternative of oil because the scientists recognize bacteria as the potential source of synthesis of polymeric compounds.
However, the beginning of industrial usage of bacteria set the issue of increasing of bacteria metabolic activity and fostering of separate processes of such metabolism.
In fact, people cultivate microbes on the artificial growth media. Such environment should contain the original substances necessary for the metamorphic and energetic metabolism. The conditions of cultivation depend on the characteristics of one or another type of bacterium. In particular, the major part of bacteria can grow within one or two days at 37 °C. Some of them, however, require longer time up to three or four weeks if speaking about Mycobacterium tuberculosis. Moreover, scientists should take into account both plastic and energetic needs of microorganisms. Bacteria need nitrogen, carbon dioxide, and hydrogen. Consequently, the microbe growth media should contain the sources of nitrogen and water that bacteria need to build their organic compounds such as blood, serum, yolk, parts of liver and others. Also, not only natural substances should be included in the growth media but also some non-organic phosphates such as ions of iron, copper, calcium, potassium, and others. Thus, the bacterial growth media should have a definite viscosity, density, and humidity up to 20% of water. It also should be transparent and sterile.
There are more factors, such as temperature, drying or desiccation, radial energy, high pressure, ultrasonic and duration of cultivation, affecting the microbus metabolism (Sundararaj, Mudaliar, Anthoniraj, Kannan, Muthukaruppan).
As for the temperature, bacteria survive in significantly low temperatures in laboratories, in particular, up to -190°C of liquid air and -253°C of liquid nitrogen. Low temperatures prevent the processes of decay and fermentation. Therefore, people built cellars to store the food products from the ancient times. As for the high temperatures, bacteria die at 50-60°C in 30–60 minutes and at 100°C – in 2–3 minutes relatively. However, thermophiles bacteria can stay alive up to +160 °C.
Resistance to the desiccation is different for various microorganisms. Gonococcus, Meningococcal, Treponema, Leptospira, Hemophile, and Phages are sensitive to the drying process. Contrary, Vibrio cholera can survive two days in case of desiccation, whereas Shygeli – 7, Plague bacillus – 8, Diphtheria bacillus –30, Typhus fever bacillus – 70, Staphylococcus and Mycobacterium tuberculosis– 90 days. By the way, Anthrax bacillus saves its activity up to 10 years.
Various types of radial energy affect differently and have bactericidal or sterile activity. Thus, infrared radio waves do not provoke any changes in living cells, whereas x-rays cause mutation and even death of cells. There are carbothermic bacteria inside the uranium ores and Micrococcus radio Trans, extracting from the waters of nuclear reactors that can resist radio energy. The strongest mutagens are ultraviolet radiation with the waves up to 253.7 nm. It causes the end of DNA replication and, as a result, the end of microbic cell division. The only one exception Photosynthesize and Cyanobacteria can develop with light. All other prokaryotes mutate during the night time.
The impact of high atmosphere pressure 100–900 kPaA on the sea and ocean depth cannot cause much harm to the bacteria which habituate in deep waters from 1,000 to 10,000 meters. Yeast keeps living characteristics under the pressure of 500 kPaA. Mould fungi keep the pressure up to 303 975 kPaA. As for the ultrasonic, it possesses some bacterial qualities, which can be used to sterilize the food and making vaccine and injection solutions.
The concentration of the H+ and OH ions in the water solution defines the reaction of the growth media. It influences on the saturation of the substances of the nutritious substrate and their arrival at the cell. The major part of procaryote relate to the neutrophils or рН 6,5-7,5. However, many bacteria can multiply in the broad range of pH from 4 to 9. Moreover, acid tolerance bacteria, such as fermented milk, vinegar, propionate and others can accumulate organic acids in the process of cell metabolism. As for basic patient bacteria, they involve ammonifying, nitrite and enterobacteria. Such factor is applied for the fostering of either the growth of one type of microbes or growth and activity inhibition of another one.
The duration of cultivation also has a practical value because the changes of the chemical composition and pH environment take place. Multiple stage absorption of nutrients, as well as accumulation of the products of metabolism in the environment and microbes body, occur. The same organisms can produce various components depending on the term and period o growth and time of extracting of the final product.
Regulating the composition of the environment we can get the possibility to foster or delay the reaction and formation of any components. If we apply the models with non-optimal start concentration of the nutritious substances, it will lead to the irrational waste of core functions, low performance, and escape. Thus, the choice of the optimal start concentration of the components and physical factors affecting the moderate growth of bacteria and their metabolism heads active synthesis of a particular product. Thus, if we change the medium, we will increase the multiplication. For instance, insertion of sugar allows activating the growth of metabolism. At the same time, the reduction of the total acidity level after adding the buffer solutions will result in the increasing of the organic acids. Accumulating in medium acids can slow down the process of microbic growth and reproduction.
The largest role in the changes of bacterial metabolism, their growth and development belong to the sources of carbon and nitrogen. Adding available nitrogen and carbon substances lead to the growth of synthetic processes, activation of the process of cell division. It has been widely used in the industrial growth of cell and biotechnical methods of sewage, soil, and air. The same principle lays the foundation for the increasing of fertility of soil, which states for the adding to the ground nitrogen fertilizer. In line with the mentioned before factors not only an improvement of nutrition, but all soil microflora happen.
Medium depletion of organic and mineral components lead to the two consequences: the reduction of bacterial metabolism transiting to the state of rest, a search of bacteria other sources of nutrients, never being used before.
Each type of microbe can be multiplied in a particular range of pH environment. Getting used to the narrow zones of environmental reaction is the result of microorganism evolution. There are microbes such as yeast, fermentation milk, vinegar, propionate able to reproduce and multiply in the acid medium, whereas Bacillus subtilis and others actively increase in the neutral medium. The alkaline condition is excellent for putrefactive bacteria.
In the process of their vital activity, the microorganisms change the reaction of the medium as a result of the emission of the products of metabolism affecting the acidity by their cells. The various attitude of the microbes to the response of the medium has been used to provide the conditions for growing useful bacteria as well as fighting with the harmful ones.
Different bacterial groups possess different ability to absorb both organic and non-organic nutritious substances as well as their assimilation from nature.
The index of specialties of bacterial metabolism depending on both physical and chemical factors allows regulating the composition and quality of the nutritious environment for the production of necessary substances, biodegradation of toxic components and preventing the growth of separate pathogenic groups of microbes.
Works Cited
Dr. Sundararaj T., Mudaliar A.L., Anthoniraj S., Kannan N., Muthukaruppan S.M. Microbiology. Tamil Nadu, 2004. 248 p.
