Human impact, or the anthropogenic impact on the environment, encompasses a plethora of issues and topics.

Anthropogenic impact often arises with a negative connotation due to issues of; pollution, deforestation, global warming etc. Anthropogenic impact does, however, also include beneficial effects such as the development of antibacterial solutions that help improve hygiene and reduce the incidence of bacterial born disease.

Rhodospirillum rubrum (R. rubrum) is a type of bacteria that can live both aerobically and anaerobically. Meaning it can grow with oxygen (aerobically) and without oxygen, by using light to produce energy (anaerobically). R. rubrum is a cell with unique characteristics, exhibiting a purple colour derived from the carotenoid pigments: rhodovibrin and spirilloxanthin. Each bacteria cell takes on a spiral shape; refer to figure below.

Gram positive and gram negative bacteria





Gram positive and gram negative bacteria have a very similar internal structure. The reason bacteria is classed as either gram negative or gram positive is based on the external structure of the cell. Gram negative bacteria have a unique outer membrane, a thinner layer of peptidoglycan, and a periplasmic space between the cell wall and the membrane. In the outer membrane, gram negative bacteria have lipopolysaccharides (LPS), porin channels, and murein lipoprotein all of which gram positive bacteria lack. This extra external layer (as shown in figure below) makes gram negative bacteria more immune to antibiotics than gram positive bacteria.

Bacterial Resistance to Antibiotics





Bacteria, like most living organisms evolves over time, however, the evolution of bacteria generally means that they have become more resistant to antibiotics.

Currently around 70% of the bacteria that cause infections in hospitals are resistant to at least one of commonly used drugs in hospitals.

The emergence of resistance is where there is a genetic change in the bacteria. There are two types of genetic change, spontaneous mutation in the bacterium’s DNA and the transferring of antibiotic resistant genes.

Spontaneous mutation works by the bacteria mutating to eliminate the effect of the main function of antibiotics. This works by the bacteria no longer needing the protein which it once relied on; and would have been killed if the antibiotics disabled it. In addition to this, the bacteria can mutate the target protein of the antibiotics making the antibiotics ineffective. Finally in the spontaneous mutation of bacteria, the bacteria can genetically mutate to produce more enzymes of which the antibiotics is targeting; resulting in there being too many to incapacitate.

The second form of genetic change in through the transfer of antibiotic resistant genes. This works simply by the antibiotic resistant gene from one bacterium being transferred or “borrowed” by another bacterium.

What are antibiotics and how do they work?





An antibiotic is a selective poison that works within the body. It has been selected so that it will kill the desired bacteria, but not the cells in the body. The overall purpose of an antibiotic is to inhibit the growth and multiplication of microorganisms (bacteria). The main way that many antibiotics work, is by incapacitating an essential bacterial protein. However different types of antibiotics affect different bacteria in different ways. For example, an antibiotic might impede a bacterium's ability to produce energy through the processing of glucose, or impede its ability to construct its cell wall. As a result of this happening, the bacterium dies instead of reproducing.

The process of evolution of bacteria creating “Super Bugs”





Modern medicine has noticed a recent development happening with bacteria becoming increasingly resistant to antibiotics. This poses a great threat as many previously treated bacterial infections are now no longer treatable by antibiotics such as penicillin. Many antibacterial solutions work due to a physical disruption, therefore bacteria cannot become "immune" to such chemical solutions. As a result these disinfecting techniques will likely continue to work against bacteria for centuries to come. The figure below shows the chemical process used to inoculate the super bugs through a suicidal beta lactam ring.

How different types of disinfectant kill bacteria





Soap - contains many amphillic molecules which is similar to most detergents. The molecules bind to lipids on one end and bind to water on the other end. The scrubbing motion done when cleaning with soap causes these molecules to bind against the lipid membrane of bacteria. When it is then washed off with water the membranes will be ripped off the bacteria and into pieces.

Alcohol – has the ability to inoculate a wide range of bacteria due to the many ways alcohol interferes with the functions of the bacteria cells. Fast evaporation results in cell dehydration, giving the ability to dissolve in some non-polar environments results in lipid membrane disturbance. Alcohol also has the ability to penetrate some bilayer groups such as fats and lipids.

Oxidizing agent - is usually used on inorganic surfaces such as tables and benches, as it can easily damage living tissues in the body. These agents work to oxidize by ripping electrons away from cell membranes. This results in cell lysis which can ultimately eventuate to the cell dying.

Disinfectants - many different substances are used as disinfectants, these include alcohols, antiseptics, aldehydes; such as ortho-phthalaldehyde, bleaches, most commonly though is hydrogen peroxide and also iodine and potassium permanganate solutions are included. Phenolic compounds also have anti-bacterial activity and are therefore often used in household disinfectants, and in disinfectant hand-washes and soaps.





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