A review the soil moisture as a factor affecting the microbiological and biochemical activity of soil

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Regards

Microflora of the water.In the waters of fresh water reservoirs, various bacteria are found: rod-shaped (pseudomonads, aeromonads), coccoid (micrococci), convoluted. Water pollution with organic substances is accompanied by an increase in the number of aerobic and anaerobic bacteria and fungi. Especially a lot of anaerobes in the silt and at the bottom of reservoirs. Along with polluted stormwater, snowmelt and sewage, lakes and rivers contain representatives of normal human and animal microflora (E. coli, Citrobacter, Enterobacter, enterococci, Clostridium) and pathogens of intestinal infections (typhoid, paratyphoid, dysentery, cholera, leptospirosis, enterovirus infections). Thus, water is a factor in the transmission of pathogens of many infectious diseases. The microflora of water in the oceans and seas is also represented by various microorganisms, including luminous and halophilic (salt-loving). They affect shellfish, fish, when used in food, food toxicoinfection develops. The water of artesian wells practically does not contain microorganisms, since the latter are retained by the upper layers of the soil.

Hygienic requirements and quality control apply to drinking water supplied by centralized systems of drinking water supply, as well as centralized water supply systems that supply water simultaneously for drinking and technical purposes, and establishes hygienic requirements and rules for monitoring the quality of drinking water. The standard does not apply to water with non-centralized use of local sources without a distribution network of pipes.

If bacterial contamination of water exceeds the permissible limits, an additional study should be conducted for the presence of bacteria-indicators of fresh fecal contamination. Such bacteria include thermotolerant coliform bacteria, fecal coliform bacteria that ferment lactose to acid and gas at a temperature of 44 ° C for 24 hours and do not grow on a citrate medium. Fresh fecal contamination is also indicated by the detection of Enterococcus. The presence of bacteria of the genera Citrobacter and Enterobacter indicates a relatively long-standing fecal contamination. The presence of Clostridium also indicates fecal contamination, the duration of which is difficult to say unequivocally (spores can persist in the environment for a long time). A sharp increase in the content of thermophilic bacteria may indicate contamination of the soil by decomposing waste, as they multiply in self-heating manure and compost.

In addition, water contamination is assessed by detecting pathogenic microbes with a fecal-oral transmission mechanism (enteroviruses, Shigella, Salmonella, cholera vibrions, etc.).

Microflora of air.Air is an unfavorable environment for the development of microorganisms. The degree of air pollution depends on a large number of different factors: the time of year (winter – summer), urban or rural areas, plains or mountains, the air of open spaces or closed rooms.

Microflora of air is represented mainly by cocci (Staphylococcus, Streptococcus, sarcina), saprophytic bacteria, fungi. In the air of closed rooms, microflora that is released from the person (respiratory tract) accumulates. Pathogenic microflora enters the air when coughing, sneezing (when the act of sneezing, 104-106 microbial cells enter the air). In the form of aerosols in the air can be pathogens of acute respiratory infections, influenza, diphtheria, whooping cough, tuberculosis, measles, pneumonic plague, etc.Bacteria in the form of dried particles of size from 1 to 100 microns can be in the dust.

Sanitary-indicative microorganisms in the air of hospital premises are β - and α-hemolytic staphylococci and streptococci. They can be the cause of purulent-inflammatory diseases when they get into an open wound, so there should be no purulent microflora in operating rooms, dressing rooms, delivery rooms, and intensive care wards.

Sanitary and hygienic examination of air is carried out using sedimentation (natural sedimentation) and aspiration (forced sedimentation) methods and includes the determination of the total number of microbes in 1 m3 and the detection of pathogenic hemolytic staphylococci and streptococci. Using the sedimentation method (Koch's method), you can get a General idea of the microorganisms found in the air. Aspiration methods make it possible to determine not only the qualitative, but also the quantitative content of bacteria in a certain volume of air.

The microflora of the soil.The soil is populated by a variety of microbes that participate in the processes of soil formation and self-cleaning of the soil, the natural cycle of nitrogen, carbon, etc.the soil is home to bacteria, fungi, protozoa and lichens. The number of bacteria in the soil is 10 billion cells per 1 g. on the surface of the soil, there are relatively few microorganisms, because they are adversely affected by UV rays and drying. The largest number of microorganisms is contained in the upper layer of the soil up to 10 cm thick. as the soil gets deeper, the number of microorganisms decreases, and at a depth of 3-4 m they are practically absent. The composition of the soil microflora depends on its type and condition; vegetation composition, temperature, humidity, etc.Most soil microorganisms are able to develop at a neutral pH value, high relative humidity and a temperature of 25-45oC.

Nitrogen-fixing bacteria that can absorb molecular nitrogen (azotobacteria, mycobacteria, and nitrogen-fixing bacteria) live in the soil. Varieties of cyanobacteria or blue-green algae are used to increase the fertility of rice fields. The soil is a place of concentration of spore-forming rods of the genera Bacilus, Clostridium. Non-pathogenic bacilli (B. megaterium, B. subtillis) along with pseudomonads, Proteus and some others are ammonifying, they are a group of putrid bacteria that carry out the mineralization of organic substances. Pathogenic spore-forming sticks (pathogens of anthrax, botulism, tetanus, gas gangrene) can persist for a long time and even multiply in the soil.

Intestinal bacteria (Escherichia coli, pathogens of typhoid, salmonellosis, dysentery) can get into the soil with feces, but there are no conditions for their reproduction and they gradually die. In clean soils, Escherichia coli and Proteus are rare, the detection of these bacteria is an indicator of soil contamination with human and animal feces and indicates its sanitary and epidemiological problems in terms of transmission of pathogens of intestinal infections. There are also numerous fungi in the soil. They are involved in soil-forming processes, nitrogen conversion, and release biologically active substances, including antibiotics and toxins. The number of protozoa in the soil ranges from 500 to 500 thousand per 1 g. Feeding on bacteria and organic residues, the protozoa cause changes in the composition of soil organic substances.