How do saprophytic bacteria get energy

Therefore, these bacteria are also known as photolithographs. Chemoautotrophs: These bacteria do not require light lack the light phase but have the dark phase of photosynthesis and pigment for their nutrition. These bacteria oxidize certain inorganic substances with the help of atmospheric oxygen.

This reaction releases the energy exothermic which is used to drive the synthetic processes of the cell. Elemental Sulphur Oxidising Bacteria :Denitrifying sulphur bacteria oxidize elemental sulphur to sulphuric acid e.

Nitrosomonas oxidises NH3 to nitrites. B Heterotrophic bacteria: The heterotrophic bacteria obtain their-ready made food from organic substances, living or dead. These are of three types: a Photoheterotrophs These bacteria can utilize light energy but cannot use CO2 as their sole source of carbon.

They obtain energy from organic compounds to satisfy their carbon and electron requirements. Bacteriochlorophyll pigment is found in these bacteia e. These bacteria secrete enzymes to digest the food and absorb it. The enzymes secreted break down the complex compounds such as carbohydrate and protein, into simpler soluble compounds, which are easily absorbed. Examples are Bacillus mycoides, B. They may be harmless or may cause serious diseases. Parasitic bacteria which cause various diseases in plants and animals are known as pathogens, e.

They are beneficial to the organisms. The common examples are the nitrogen-fixing bacteria, e. Rhizobium spp. Heterotrophic bacteria require organic sources of carbon such as sugars, fats and amino acids.

Saprophytic bacteria are an example. They attain their nutrition from dead organic matter. Using enzymes, these bacteria will break down complex compounds and use the nutrients to release energy. Saprophytic bacteria are decomposers and play an important role in ecosystem by releasing simpler products which plants and animals can use.

Phototrophic bacteria are autotrophs that absorb light energy, then utilize this in photosynthesis to create cellular energy. There are two types of phototrophs. Those which do not produce oxygen as a byproduct are termed anaerobic phototrophs, while those which do produce oxygen are termed aerobic phototrophs. Cyanobacteria are an example of bacteria which execute photoautotrophic nutrition. Both autotrophs and heterotrophs can be phototrophs.

Heterotrophic phototrophs consume organic carbon in addition to producing organic molecules via photosynthesis. These bacteria obtain chemical energy from their surroundings and convert it into adenosine triphosphate ATP for cellular use. These bacteria are also considered chemotrophs and obtain energy from oxidation-reduction reactions of inorganic compounds such ammonia, hydrogen sulfide and iron.

Antiseptics are weaker chemicals applied to wounds and sores to prevent micro-organisms from multiplying. Decomposers Fungi and most bacteria are saprotrophic and have an important role in an ecosystem as decomposers, breaking down dead or waste organic matter and releasing inorganic molecules. These nutrients are taken up by green plants which are in turn consumed by animals, and the products of these plants and animals are eventually again broken down by decomposers.

Sewage treatment employs bacteria which break down harmful substances in sewage into less harmful ones. Aerobic bacteria decompose organic matter in sewage in the presence of oxygen. Once the oxygen is used up the aerobic bacteria can no longer function, and anaerobic bacteria continue the decomposition of organic matter into methane gas and carbon dioxide, along with water and other minerals.

The digested sludge is rich in nitrates and phosphates and can be spread on the land as fertiliser. Some sewage treatment plants have used the methane as a cheap form of fuel biogas. Anaerobic micro-organisms are also being used to convert carbohydrate-rich crops, such as cane sugar and maize, into ethanol which is used as a substitute for petrol in cars.

This biofuel or gasohol is used widely in Brazil, which has meagre oil resources. The carbon cycle Fats, carbohydrates and proteins all contain carbon atoms, so dead and waste organic matter contains a lot of carbon. In breaking this down, saprophytic bacteria and fungi take up some carbon to build their own bodies, and release some as carbon dioxide during respiration.

However, the carbon cycle need not involve decomposers because autotrophs can access carbon from the abundant carbon dioxide in the air. The nitrogen cycle All living things need nitrogen, it is an essential component of all proteins.

Nitrogen-fixing bacteria are able to convert or fix nitrogen gas from the air into nitrogen compounds. Plants take up these nitrogen compounds through their roots, combine them with products of photosynthesis, and make proteins. Animals obtain the protein they need by eating the plants or other animals.

Some nitrogen-fixing bacteria are free- living in the soil, others live in small swellings, or nodules , on the roots of some plants, particularly members of the legume family such as clover, peas and beans. This is a symbiotic arrangement, the plant gets nitrogen compounds and the bacteria receive carbohydrates from the plant.

Dead and waste organic matter contains ammonium compounds which are converted by nitrifying bacteria into nitrates, and these are assimilated by plants. Denitrifying bacteria remove nitrates and ammonium compounds from the soil by converting them into nitrogen gas. Digestion Despite the vast quantities of cellulose eaten by herbivores, mammals themselves cannot digest cellulose and rely entirely on the action of carbohydrate-digesting bacteria in their guts.

These secrete the enzyme cellulase which splits the cellulose into monosaccharides which can be absorbed by the gut. Ruminants cud-chewing mammals such as cows have a large chamber in the stomach called a rumen which contains huge numbers of these bacteria.

Huge numbers of bacteria, particularly Escherichia coli , also inhabit the human colon. Other bacteria synthesise vitamins and amino acids, and others may contribute to our resistance to disease by competing for space in the gut with harmful bacteria. It is important therefore to maintain a healthy gut flora. Biotechnology The manipulation of cells, particularly micro-organisms, to produce useful substances is referred to as biotechnology.

Micro-organisms are exploited extensively in the fields of medicine, agriculture, food production, waste disposal and many other industries. We make use of some saprophytic bacteria which do not produce waste products harmful to humans. The bacterium Lactobacillus feeds on milk, turning it into yoghurt. Other bacteria and fungi help in cheese-making and are responsible for distinctive flavours.