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Made by Rohit. R. Mahadev{Student}

Microbial Nutrition

Definition of Nutrients > Nutrients are substances used in biosynthesis and therefore are required for microbial  growth.

The common nutrient requirements. Analysis of microbial cell composition shows that over 95% of cell dry weight is made-up of a few major elements : Carbon, Oxygen , Hydrogen , Nitrogen , Phosphorous , Sulfur , Calcium ,  Manganese & Iron. These are called macro elements or macro nutrients because they are required by microorganisms in relatively large amount. The first six composed of carbohydrates, proteins , lipids & nucleic acid. Amino acids --> There are 20 amino acids:- 21 is discovered recently 21th-->Sclenocysteine. Isoleucine	Alanine	       Leucine	        Asparagine	Lysine Aspartate	Methionine	Cyateine	Phenylalanine	Glutamate Threonine	Glutamine	Tryptophan	Glycine	       Valine Proline	       Serine	        Tyrosine	Arginine	Histidine The remaining four macro element exist in the cell as cations and play a variety of roles for e.g. Potassium is required for action by number of enzymes include some of those involved in protein  synthesis, Calcium among other functions contributes to the heat resistance of bacterial  endospores. Clostridium species > Containing endospores have calcium. Bacillus species --- Two microorganisms which have endospores Magnesium serves as a co-factor for many enzymes, complexes with A.T.P. and stabilizes ribosome and cell membranes. Iron is a part of cytochrome and a co -factor for enzymes and electron carrying proteins. In addition to microelements all microorganisms require nutrients in small amounts. These are called micronutrients or trace elements. The micro nutrients Mn, Zn , Co , Mb , Ni , Cu are needed by most cells however cells require such small amounts that contamination from water , glass ware and regular media components are  adequate for growth. In nature micro nutrients are ubiquitous and probably do not usually limit growth. Micro nutrients are normally a part of enzymes and co-factors and they aid in the catalysis of reactions and maintain protein structures. Zn is present at the active sight of some enzymes but can also be involved in the association of regulate and catalyses sub units. Mn adds many enzymes that catalyses the transfer of phosphate groups. Co is required for nitrogen fixation and Co is a component of Vitamin B 12. Besides the common macro elements and trace elements microorganisms may have portion required that reflect their specific morphology or environment. Diatoms need Silicic acid to construct their beautiful cell walls of silica. Although most procaryots do not require large amount of sodium. Many archaea growing in saline lakes and oceans depend in the presence of high concentration of sodium ion. Finally it must be emphasized that microorganisms require a balanced mixture of nutrient if an essential nutrient is in short supply microbial growth will be limited regardless of the  concentration of other nutrients. Requirement for C, H, O & Electrons:- All organisms need carbon, hydrogen, oxygen and a source of electrons. Carbon:- Carbon is needed for the skeleton or backbone of all the organic molecules from which organism are built.

H &O:- H and O are important element found in organic molecules. Electrons are needed for two reasons:- 1 > The movement of electrons through electron transport chain and during ordinary oxidation reduction reactions con provide energy for use in cellular work. 2 > Electrons are needed to reduce molecules during biosynthesis e.g. reduction of CO2 to form organic molecules The requirement for C, O and H often are satisfactory targets because molecules serving as carbon sources often contribute H & O as well. For instance many heterotrophic organisms that use reduced preformed organic molecules as their carbon source. They can also obtain H, O and electrons from the same molecules because the electron provided by these carbon source can be used in electron transport as well as other oxidation and reduction reactions. Many heterotrophs also use carbon sources as their energy source. Indeed the more reduced organic carbon source the higher is its energy content. Thus lipids have an higher energy content than carbohydrates. However one carbon source CO2 only supplies C and O so it cannot be used as a source of H, electron or energy. This is because CO2 is the most oxidized form of carbon lacks hydrogen and is unable to donate electron on oxidation reaction. Organism that use CO2 as the sole or principle source of carbon are called autotrophy because CO2 cannot supply their energy needs. They now obtain energy from other sources such as light or reduced organic molecules. A most remarkable nutrition of heterotrophy microorganisms is their extraordinary flexibility to their carbon requirements. Actinomycete common soil bacteria will decay amyle alcohol, paraffin and even rubber. Some bacteria seem able to employ almost anything as their carbon source; for e.g. Burkholderia cepacia can use over 100 different carbon compounds. Microbes can decay indigestible human made substances such as pesticides. This is usually accomplished in complex microbial community. These molecules are sometimes degraded in the process of growth promoting calcium matelotes which is known as co-metabolites. Other microorganisms can use products of these breakdown process as nutrients in contrast to these bacterial omnivores. Some bacteria are exceedingly fastidious and catabolise only a few carbon compounds. Certain methyl tropic bacteria metabolize methane, methanol, carbon dioxide, formic acid and related one carbon compound. Persisting members of the genus Leptospirosis only use long source fatty acids as their carbon source. Nutrition type of microorganisms There are only two source of energy available to the organism :- 1) Light (photo tropes ) 2) The energy derived from oxidation of organic or inorganic molecules ( organotropes) Photo tropes --> they use light as their energy source Kemotropes --> obtain energy from oxidation of chemical compounds ( either organic or in organic) Lethotropes( rock eaters)-->They use reduced inorganic substances as their electron source. Organotorpes--->They use reduced organic compounds as their electron source Despite the great metabolic diversities seen in the microorganism most may be placed in one of the five nutritional classes Sources of carbon, energy and electrons Carbon source:- 1 > Autotropes --> CO2 sole or principle biosynthetic carbon source. 2 > Hetrotropes --> reduced preformed organic molecules from other microorganisms as their carbon source. Energy sources:- 1 > Phototropes --> Light. 2 > Khemotropes --> Oxidation of organic or inorganic compounds. Electron source:- 1 > Lethorropes --> Reduced inorganic molecule. 2 > Organotropes --> Reduced organic compounds.