Physical and Chemical Control of Growth and Viability

Physicaland Chemical Control of Growth and Viability


Physicaland chemical control of growth and viability

Metabolismrefers to all the chemical reactions that usually takes place in anorganism, and the process facilitates the breakdown of complexmolecules to produce energy (Cummings, 2007). The energy producedfrom this process is used by the body cells to build up more complexmolecules. Since, cell metabolism refers to the total energy consumedand released by a cell, catabolic and anabolic reactions occur inbodies at the same time and this enables bodies to function properly. Catabolism refers to the process that comprises of all the reactionsthat take place when larger particles break down into lessermolecules to release energy(Cummings, 2007 Boundless, n.d.).Forexample, lipids, DNA, carbohydrates, proteins, and RNA are brokeninto amino acids, fatty acids, nucleotides, and sugars. On the otherhand, Cummings (2007) and Boundless (n.d.) refer anabolism as theprocess that encompasses all reactions that take place when smallermolecules assemble to create larger ones, and the energy produced isstored in newly created chemical bonds. For example, amino acids,fatty acids, nucleotides, and sugars are processed to form DNA,carbohydrates, proteins, and RNA.

AnETC (electron transport chain), refers to a series of compounds thatusually transfer electrons from donors of electrons to acceptors ofelectron through a redox reaction, the transferred electrons are thencoupled with the proton ions [H+] being transferred across a membrane(Singh&amp Kapoor, 2010).This reaction results in a gradient of electrochemical proton thatdrives the ATP synthesis, in other words, the creation of chemicalenergy in the form of ATP (adenosine triphosphate). The finalelectron acceptor in electron transport chain (ETC) is molecularoxygen.

EscherichiaColi is a rod or bar-formed or shaped gram-negative bacterium. Inaddition, the bacterium normally lives in the lower gastrointestinaltract in all warm-blooded animals. Hydrogen, carbon, phosphorus,oxygen, sulfur, and nitrogen, and these chemical elements arenecessary for building almost all the bacteria cellular components.Other elements that are needed to perform specific processes as wellas make specific structures are selenium, sodium, calcium, and iron.All these elements are necessary for the survival of the bacteria,and they are known as the building blocks. The growth factors are theimportant metabolites that the organisms need, but they are not ableto synthesize them(Boundless, n.d.).Growth factors of E. coli are nucleotides, amino acids, vitamins, andfatty acids. Medium pH range is very essential for the bacteria celldensity and growth rate.

Themost favorable growth Ph for Escherichia coli is near neutral. Inaddition, the bacteria can grow well within the pH range of threeunits 5.5 to 8.5. Singh &amp Kapoor (2010) assert that if organicbuffers, phosphate buffers, aeration conditions, and sugar contentsare carefully balanced they can maintain a favourable culture mediumthat can ensure optimum growth for the E. coli. Moreover, oxygenconcentration is very essential for the growth of E. coli. Becausethe cells of the bacteria produce a lot of acetic acid which lowerstheir growth rate, availability of oxygen enables them to access manyorganic acids. For example, carbon enables them to maintain thegrowth medium pH near basic or neutral ranges. In addition, theoptimal growth temperature of E. coli is 37 degrees Celsius(Singh&amp Kapoor, 2010).TheE. coli cannot develop well if the temperatures are more than 42degrees Celsius however, the bacteria can stand lower temperaturesbut the growth rate will be lower. Also, a careful balance betweenchemical contents and nutrients usually maintains the most favourableosmolarity media for E. coli development and growth. Despite the factthat E. coli cells can multiply on different concentrations ofnutrients, some strains usually require different optimal nutrientsconditions. The mediums that are commonly used are yeast extracts,sodium chloride, and peptone. Conclusively, medium agitation resultsin increased growth rate for all the E. coli cells, this is becauseagitation usually increases the bacteria’s metabolic exchangewithin the required medium.

Themost preferred drug when treating E. coli is ciprofloxacin because itblocks replication of bacterial DNA by binding to the enzyme known asDNA gyrase, thus making the double-stranded chain of bacterialchromosome to break(Mukhrajee,2008 Boundless, n.d.).In other words, it inhibits DNA gyrase that is a type 2topoisomerase. The enzyme is usually responsible for separating allreplicated DNA thus when inhibited cell division is also prevented.

Escherichiacoli can reside in a human body as a pathogen as well as a normalflora. The pathogenic state is produced because the bacteria act as‘sparring partners’ by assisting the body to keep the immunesystem in order(Mukhrajee,2008).However, the main role of human immune system in regulating thenormal flora populations is not known. E. coli mainly assist the bodyin vitamin K2 production, as well as preventing harmful bacteria fromestablishing themselves in the stomach.

Inconclusion, E. coli act as both normal floras and pathogens. E. colicharacteristics can be used to control it thus, because the bacteriausually depend on what it grow on and eats, tampering with it growthmedia can control it. For example, high temperature, high acidicmedia, as well as low oxygen levels can be used to hinder its growth.


Boundless.(n.d.). Boundless-Textbooks.Retrieved March 5, 2015, from

Cummings,B. (2007, January 1). Metabolism.Retrieved March 6, 2015, from

Mukhrajee,A. (2008). Chapter9: Cellular Respirationand Chapter10 Cell Metabolismin Cell Biology: Fundamentals and Applications. global Media, Jaipur

Singh,U. S. &amp Kapoor, K. (2010). Chapter10: Microbial Nutrition and Growth,&quotin Introductory Microbiology. Global Media, Jaipur IND. 2010