Nutritional Types of Microbes PDF

Nutritional types of microbes: Microorganisms can be classified into nutritional classes based on how they satisfy the requirements of carbon, energy and electron for their growth and nutrition. Based on Energy source: Phototrophs, Chemotrophs Based on Carbon: Autotrophs, Heterotrophs Based on El...

Nutritional types of microbes: Microorganisms can be classified into nutritional classes based on how they satisfy the requirements of carbon, energy and electron for their growth and nutrition. Based on Energy source: Phototrophs, Chemotrophs Based on Carbon: Autotrophs, Heterotrophs Based on Electron source: Lithotrophs, Organotrophs Based on Energy source: Phototrophs: Phototrophs are organisms that obtain energy from light to carry out their metabolic processes. These organisms use light energy, usually from the sun, to produce their own food through a process called photosynthesis. Example: purple sulfur bacteria and green sulfur bacteria, all green plants, algae, and cyanobacteria. Chemotrophs: Chemotrophs are organisms that obtain energy by oxidizing chemical compounds, rather than through photosynthesis (like phototrophs). They rely on the chemical energy stored in inorganic or organic compounds for growth, maintenance, and reproduction. Chemotrophs are commonly found in environments where sunlight is not available, such as deep-sea vents or within the soil. Example: Sulfur-oxidizing bacteria, Nitrifying bacteria, Iron-oxidizing bacteria, Fungi like Aspergillus and Penicillium. Based on Carbon source: Autotrophs: Autotrophic microbes are able to synthesize their own organic compounds from inorganic substances. They do not rely on other organisms for carbon sources but rather fix carbon from CO₂. Photoautotrophs: These organisms use sunlight as their energy source for synthesizing organic molecules. Example: Cyanobacteria (blue-green algae), green plants (though not microbes, they are also photoautotrophs). Process: The process is called photosynthesis, where light energy is captured by pigments like chlorophyll, and used to convert CO₂ and water into glucose and oxygen. Chemoautotrophs: These microbes obtain energy by oxidizing inorganic substances like hydrogen sulfide (H₂S), ammonia (NH₃), or iron (Fe²⁺).   Example: Nitrifying bacteria (such as Nitrosomonas and Nitrobacter), sulfur- oxidizing bacteria (such as Thiobacillus).  Process: They use the chemical energy released from the oxidation of inorganic compounds to convert CO₂ into organic compounds, a process known as chemosynthesis. Heterotrophs : Heterotrophic microbes rely on organic carbon as both their energy and carbon sources. They obtain their energy by consuming organic matter produced by other organisms. Photoheterotrophs: These organisms use light as an energy source, but they require organic compounds for carbon.  Example: Purple non-sulfur bacteria and green non-sulfur bacteria.  Process: They use light for ATP production through photosynthesis, but unlike autotrophs, they cannot fix CO₂ and thus require organic carbon for growth. Chemoheterotrophs: These organisms obtain both their energy and carbon from organic compounds.  Examples: Most bacteria, fungi, humans, and animals.  Process: The organic compounds, such as carbohydrates, lipids, and proteins, are broken down via cellular respiration or fermentation. During cellular respiration, glucose (or other organic molecules) is oxidized to release energy (ATP) and produce CO₂ and water. Based on Electron source: Lithotrophs: Organisms that use reduced inorganic substances as their electron source. Types of Lithotrophs: 1. Lithoautotrophs: These organisms use inorganic compounds as both an energy source and a carbon source (usually fixing carbon dioxide to produce organic compounds). 2. Lithoheterotrophs: These organisms use inorganic compounds for energy but require organic compounds from the environment as their carbon source. Examples: Sulfur-oxidizing bacteria (use sulfur compounds as an energy source), Iron-oxidizing bacteria (use iron as an energy source) , Ammonia- oxidizing bacteria (nitrifying bacteria), etc. Organotrophs: Organisms that obtain energy by oxidizing organic compounds. They rely on organic substances, such as carbohydrates, fats, and proteins, for both their energy and carbon source. Examples : Humans, Animals, Fungi like Aspergillus, Penicillium, Bacteria like Escherichia coli ,Clostridium