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Conditions for the Growth of Microorganism: Food, water, and shelter are the essential necessities for humans to survive. Microorganisms have the same requirements as humans: they require nutrients for energy, water to stay hydrated, and a suitable environment to thrive. The optimum settings differ according to the species of microbe, but they all contain elements from these factors given below. Read on to learn more about the conditions for the growth of microorganisms.
Microorganisms, or microbes, are a diverse group of generally minute simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses.
A steady increase in all the chemical components of an organism may result in an increase in cell size, cell number, or both are known as growth. For microorganisms to thrive, their surroundings must be ideal. The factors that influence the growth requirements can be categorised as intrinsic, extrinsic, and implicit factors.
While all microbes have the trait of being extremely small, their environmental requirements are fairly varied. They have similar requirements, but the resources required to accomplish them are vastly different.
The internal self-parameters of microorganisms are referred to as intrinsic factors. These factors include:
Fig: pH Scale
Moulds and yeasts can grow at lower pH than bacteria, while Gram-negative bacteria are more susceptible to low pH than Gram-positive bacteria. Moulds thrive best in a pH range of 1.5 to 9.0, yeasts in 2.0 to 8.5, Gram-positive bacteria in 4.0 to 8.5, and Gram-negative bacteria in 4.5 to 9.0. Microorganisms can be classified into the following groups based on their pH ranges:
Microorganisms require water in a readily available form. The ratio of the food’s water vapour pressure to that of pure water at the same temperature can be used to calculate the food’s water activity. Because no meal may have a water activity of 0 or 1, it ranges from >0 to 1.
Based on the nature of available water for growth and its amount, microorganisms can be grouped as:
A substance’s oxidation-reduction or redox potential is defined as a measurement of electron transfer between atoms or molecules. Eh is the standard abbreviation for the oxidation-reduction potential, which is measured in millivolts (mV). Food’s redox potential is determined by the:
The Eh range at which certain microorganism groups can thrive is as follows:
Carbon makes up 50% of the dry weight of cells. It is the structural backbone of all organic compounds. The microorganism can be classified into two based on the ability to obtain carbon from different sources.
A. Chemoheterotrophs: Obtain carbon from their energy source: lipids, proteins, and carbohydrates.
B. Chemoautotrophs and Photoautotrophs: Obtain carbon from carbon dioxide.
2. Nitrogen, Sulphur, and Phosphorus
A. Nitrogen: Makes up 14% of dry cell weight. Found in amino acids, DNA, and RNA.
B. Sulphur: Forms proteins and some vitamins (thiamin and biotin).
C. Phosphorus: Forms DNA, RNA, ATP, and phospholipids.
3. Other Elements
Potassium, magnesium, and calcium are often required as enzyme cofactors. Calcium is required for cell wall synthesis in Gram-positive bacteria.
Organisms that use molecular oxygen (O2 ) produce more energy from nutrients than anaerobes. We can classify microorganisms based on their oxygen requirements:
A. Obligate Aerobes: Require oxygen to live.
Example: Pseudomonas, a common nosocomial pathogen.
B. Facultative Anaerobes: Can use oxygen but can grow in its absence. Have a complex set of enzymes.
Examples: E. coli, Staphylococcus, yeasts, and many intestinal bacteria.
C. Obligate Anaerobes: Cannot use oxygen and are harmed by the presence of toxic forms of oxygen.
Example: Clostridium bacteria that cause tetanus and botulism.
D. Aerotolerant Anaerobes: Cannot use oxygen but tolerate its presence. Can break down toxic forms of oxygen.
Example: Lactobacillus carries out fermentation regardless of oxygen presence.
E. Microaerophiles: Require oxygen, but at low concentrations. Sensitive to toxic forms of oxygen.
Fig: Nutrient Content
Extrinsic factors are those that are influenced by circumstances beyond one’s control(external conditions). These elements include:
Fig: Thermometer Used to Measure Temperature
The temperature of the environment has an impact on enzyme processes and microbiological development. The temperatures at which yeasts and moulds grow span a wide range of 10–35° C. Every bacterial species has distinct temperature requirements for growth, which are mostly governed by the temperature requirements of its enzymes. Each creature will have the following characteristics:
Based on temperature, bacteria can be grouped as:
Microorganisms are a diverse group of generally minute simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses. For microorganisms to thrive, their surroundings must be ideal. The factors that influence the growth requirements can be categorised as intrinsic, extrinsic, and implicit factors. The pH, Availability of oxygen, Poising capacity or buffering capacity, Nutrient composition (such as protein, ascorbic acid, reducing sugars) are required in different quantities for various microbes to grow.
Microorganisms can survive in a wide variety of temperatures, having colonised various natural settings and adapted to extremes. Extreme increase and extreme decrease in the elements both necessitate evolutionary changes to macromolecules and biological systems. Changes in the composition of membrane lipids and proteins are required for adaptation to sustain in the given surroundings. Similarly, Predation, parasitism, commensalism, amensalism, allotropy, and neutrality are some of the different behaviours and reactions that can be destructive or beneficial to microorganisms.
Q.1. What are the conditions for the growth of microorganisms?
Ans: Microorganisms grow in very diverse conditions, which explains why they are found nearly everywhere on Earth. Although microbes are good at adapting to their environments, certain conditions promote microbial growth more than others. These conditions include temperature, moisture, pH, and environmental oxygen.
Q.2. How does pH affect the growth of microorganisms?
Ans: Moderate changes in pH modify the ionization of amino-acid functional groups and disrupt hydrogen bonding. This promotes changes in the folding of the molecule, promoting denaturation and destroying activity. The optimum growth pH is the most favourable pH for the growth of an organism.
Q.3. What is the importance of water for microorganisms?
Ans: Many different types of microorganisms can grow in water. Water is needed for the growth of some microorganisms. This, in turn, proves to be beneficial for us as beer and bread are made possible by the chemical activity of certain yeast strains. In addition, the proliferation of some microbes in contaminated water can aid in the digestion of the chemicals in the water.
Q.4. What are the intrinsic factors affecting the growth of microorganisms?
Ans: Intrinsic factors affecting the growth of microorganisms include nutritional content, pH levels, water activity, redox potential, etc.
Q.5. How does temperature affect the growth of microorganisms?
Ans: In general, when the temperature rises, so does enzyme activity. However, if temperatures rise too high, enzyme activity decreases, and the protein (enzyme) denatures. Every microbial species has unique temperature requirements for growth, which are mostly governed by the temperature requirements of its enzymes.
We hope this detailed article on Conditions for the Growth of Microorganisms will be helpful to you in your preparation. If you have any doubts please reach out to us through the comments section, and we will get back to you as soon as possible.
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