What are five environmental conditions that effect the growth of microorganisms and how does each one specifically effect microbial growth?
Warmth, moisture, pH levels and oxygen levels are the four big physical and chemical factors affecting microbial growth. In most buildings, warmth and moisture are the biggest overall issues present. Dampness is a big player in the growth of fungi. Just like any living thing, water is essential to the life of microbes. The rate of growth or death of a particular microbial species is influenced by a variety of physical factors in its environment including temperature, osmotic pressure, pH, and oxygen concentration. Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or slightly acidic. There are exceptions, however. Some bacteria thrive in extreme heat or cold, while others can survive under highly acidic or extremely salty conditions. Most plants and animals live in areas with very specific climate conditions, such as temperature and rainfall patterns, that enable them to thrive. Any change in the climate of an area can affect the plants and animals living there, as well as the makeup of the entire ecosystem. On land, the most important environmental conditions affecting organisms are rainfall and temperature. In our oceans, there are a number of environmental conditions that affect the growth, survival and productivity of marine organisms.
Microorganisms require specific environmental conditions to grow and reproduce. The five main environmental factors that affect microbial growth are temperature, pH, water activity, oxygen availability, and nutrient availability.
Temperature: Temperature is a major factor in microbial growth as different organisms have different optimal temperatures for growth. Generally, mesophiles prefer temperatures between 20-45°C while thermophiles prefer temperatures above 45°C and psychrophiles prefer temperatures below 20°C.
pH: pH is another important factor in microbial growth as it affects the availability of nutrients and the activity of enzymes. Most microorganisms prefer a neutral pH (6.5-7) but some bacteria can grow at an acidic pH below about 4 or an alkaline pH above 9.
Water Activity: Water activity (aw) is a measure of the amount of free water available for microbial metabolism and growth. Microorganisms require water for metabolic processes such as respiration and enzyme reactions so a low aw can inhibit their growth.
Oxygen Availability: Oxygen availability also plays an important role in microbial growth as some organisms are obligate aerobes (require oxygen), others are facultative aerobes (can use either oxygen or other electron acceptors), while still others are obligate anaerobes (cannot use oxygen).
Nutrient Availability: Nutrients such as carbohydrates, proteins, lipids, vitamins, minerals, etc., are essential for microbial growth and must be provided by the environment in order to support it.
Sources
- https://www.cliffsnotes.com/study-guides/biology/microbiology/microbial-cultivation-and-growth/growth-requirements-for-microorganisms
- https://lab-training.com/conditions-favourable-growth-microorganisms/
- https://sitn.hms.harvard.edu/flash/2020/how-microbes-grow/
Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or slightly acidic. There are exceptions, however. Some bacteria thrive in extreme heat or cold, while others can survive under highly acidic or extremely salty conditions. Microbial growth is affected by the following six factors: Food, Acidity, Time, Temperature, Oxygen and Moisture. Primary abiotic factors are light, temperature, water, atmospheric gases, and ionizing radiation, influencing the form and function of the individual. For each environmental factor, an organism has a tolerance range in which it is able to survive. In general, the higher the temperature, the more easily microorganisms can grow up to a certain point. Very high and low temperatures both obstruct the enzyme processes microorganisms depend on to survive. Moisture may limit microbial activity in a wide range of environments including salt water, food, wood, biofilms, and soils. Low water availability can inhibit microbial activity by lowering intracellular water potential and thus reducing hydration and activity of enzymes. Bacteria that require oxygen to grow are called obligate aerobic bacteria. In most cases, these bacteria require oxygen to grow because their methods of energy production and respiration depend on the transfer of electrons to oxygen, which is the final electron acceptor in the electron transport reaction. Culture-based investigations of a small number of bacterial taxa have indicated that exposure to light, and especially ultraviolet (UV) wavelengths can inactivate many microorganisms and therefore potentially reduce dust microbial community viability. In general, exposure to high O2 alone did not inhibit microbial growth strongly, while CO2 alone reduced growth to some extent in most cases. Consistently strong inhibition was observed only when the two gases were used in combination.
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