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Influence of environmental factors on microorganisms. Lector: A. Khatamov
Plan: • Effects of physical factors on microorganisms • Effects of chemical factors on microorganisms • Effects of biological factors on microorganisms.
Microbes are affected by many environmental factors. They are extremely adaptable to different conditions. For this reason, microorganisms change their properties under the influence of physical, chemical, biological and other natural factors.
Physical factors The effect of temperature. Germs need a certain optimal temperature to live. When the temperature is too high or too low, the life of the microbes slows down or stops. The temperature requirements of microorganisms are not the same. Temperature has three different effects on the microbe: optimal-favorable for the microbe, maximum-excess and minimum-insufficient. Knowing this is essential for growing germs in the laboratory.
The effect of high temperatures on microbes. Vegetative forms of the microbe are more susceptible to high temperatures. The higher the temperature, the more likely it is to kill germs. Typhoid bacteria die after 2 day at 47 0Cand after 21 hours at 59 0C. Spores also die after 20 hours at 100 0Cand 2-4 minutes at 1300C (VI Vashkov 1956). Germs are more affected by hot steam than by dry heat. For example, anthrax spores die after 1 minute in steam at 102 0C and in dry heat at 180 0C. The effect of low temperatures on microbes. Low temperatures usually do not kill germs, but stop them from growing and multiplying. Microorganisms can be stored in an anabiotic state for up to 12,000 years.
Drying and vacuuming of microbes. As a result of drying, the moisture in the microbial cell is lost, the vital activity of the microbe is reduced and it becomes anabiotic. In this case, especially in a vacuum, microbial cells are stored for 10 years. Pathogenic streptococci survive for 25 years and tuberculosis for 17 years. Rapid drying in a vacuum at low temperatures (sublimation method) is used in the preparation of live vaccines (tuberculosis, brucellosis, influenza), vitamins, enzymes and other biological drugs.
The effect of light on microbes. The bactericidal effect of light depends on its wavelength, the as shorter as stronger. Direct exposure to sunlight kills many pathogenic microbes (tuberculosis 3-5, Aphthae virus within 2 hours).
Effects of X-rays on microbes. Since 1898, under their influence, Escherichia coli has been known to kill Staphylococcus aureus, plague vibrio and other microbes. Young cells are more exposed to radiation, especially during division and development. The bactericidal effect of radiation is widely used in practice. The bactericide is used to sterilize the air in boxing and operating rooms under the influence of ultraviolet light from quartz lamps (lit for 2-3 hours). Various radioactive vaccines exposed to ionizing radiation are currently being used. The effect of ultrasound on microbes. Ultrasound waves affect the culture of microorganisms, causing a large difference in pressure and damaging the cell. Some microbes die quickly, while others are subjected to strong mechanical shocks, which disrupt physiological processes. The cytoplasm dissolves, expands in size, and the cell wall ruptures. Therefore, ultrasound is used to separate toxins, enzymes and antigens.
The effect of electric current on microbes. Constant and variable electric power has little effect on microbes. High-wave electricity kills germs. In this case, the microbe dies as a result of the vibration of the cell molecules. The effect of magnetic fields on microorganisms. Like other living things, magnetotropism has been identified in microbes. Microbes are sensitive to any force in the geomagnetic field. This leads to changes in the morphological, cultural and biochemical properties of microbes. Cells increase in size, form long filaments, and form pigment-free colonies in dense nutrient media (staphylococcus, excellent rod). Occasionally there is a change in metabolism, virulence, increased resistance to antibiotics, and so on.
The effect of hydrostatic pressure on microbes. Pressures above 108-110 a denature the protein, inactivate enzymes, enhance electrolytic dissociation, increase the elongation of liquids, and sometimes kill microbes. But there are such barophilic microorganisms that live and multiply under high pressure. For example, microorganisms have been found to grow and multiply at sea and ocean bottoms at pressures of 113-116 amperes. The effect of vibration on microbes. The effects of concussions often kill bacteria (not just viruses).
Effects of chemical factors on microorganisms Chemicals have different effects on microorganisms. Under the influence of some chemicals, the microbe begins to approach the substance (positive chemotaxis), and sometimes when the microbe is exposed to another chemical, the microbe runs away from it (negative chemotaxis). This phenomenon is called chemotaxis. For example, in meat extract, microbes approach the peptone, which is a positive chemotaxis, away from strong toxins (acids, alkalis), which is a negative chemotaxis. In the case of chemotaxis, some microbes can also accumulate in toxic chemicals and move away from certain nutrients.
Microbes are adapted to live in a certain environment: some (mold fungi) in an acidic environment, others (plague vibrio) in an alkaline environment, and most in a neutral environment (pH 6.5-7.5). This is important for the growth of microbes in artificial foods. A number of chemicals are toxic to microbes and are used to kill germs. Alkalis (NaOH, KOH) from disinfectants, acids (sulfuric acid, HCL, etc.) chlorinated lime contains 28-38% of active chlorine. Phenols (crystalline carbolic acid), oxidants (potassium permanganate), formalin (40% aqueous solution of formaldehyde), etc. are the most commonly used. The higher their concentration, the stronger the effect on the microbial cell.
In fatty acid fermentation, the intermediates are pyruvic acid, acetic aldehyde and aldol, followed by fatty acids and secondary products: butyl alcohol, acetone, CO2 and hydrogen. 25 species of fatty acid-producing bacteria have been identified. They are gram-positive, motile, spore-forming anaerobic rods of the genus Clostridium, common in manure, soil, and wastewater. Due to its glycogen and starch granulose content, it turns brown or blue when stained with iodine. The most common triggers for fatty acid reflux are: Clostridium pasteurianum - absorbs atmospheric nitrogen, decomposes sugars and other organic substances to form fatty acids, SO2 and hydrogen. Clostridium felsineum differs from other fatty acid-producing bacteria by releasing the enzyme pectinase and breaking down pectin-containing substances. 3. Clostridium butylicum - forms butyl alcohol, fatty acids when digesting carbohydrates.
Disinfection. It is performed by mechanical, physical, chemical and biological methods. Unlike sterilization, disinfection kills only pathogenic microbes, and sterilization kills all germs in a product. Antiseptics are chemical disinfectants that kill germs in wounds and other objects. Asepsis is aimed at preventing germs from entering the wound Asepsis is done by completely destroying the germs in the items that come in contact with the wounds (instruments, dressings and sutures, surgeons' hands, etc.).
Effects of biological factors on microorganisms In addition to physical and chemical factors, microbes are also affected by biological factors. When microorganisms live in natural conditions, they interact not only with the environment, but also with various microbes and other living organisms, and this is called biocenosis.
Symbiosis is when two or more species of microbes live and multiply in the same environment without interfering with each other.
Satellismis the growth, development, intensification, and coexistence of one microbe under the influence of another microbial product. Synergismis when two or more types of microbes help each other. For example azotobacter and Bac. Mycoides co-produce heteroauxin, a plant that grows well. Bac when pure azotobacter culture produces 173 mg of getroauxin. Produces 220 mg when grown with Mycoides.
Antagonism is the inability of one type of microbe to develop in an environment in which one type of microbe develops.
Parasitism is a relationship between microbes in which the parasite benefits from this relationship and harms its host, causing it to die.
The relationship between microbes of different structures and sizes - phage - is important. This is the relationship between viruses and bacteria, actinomycetes and green algae. Biological factors that affect microorganisms include antibiotics, phytoncidesand bacteriophages.
