Bacteria
Bacteria are prokaryotes. They are single celled microbes, with a single cell structure. There is no nucleus or membrane around the organelles, but instead their DNA is in a single loop. There are bacteria that have an extra circle of genetic material called a plasmid. This contains genes that give the bacteria some advantages. Bacteria can be classified into five groups. This classification is according to their shapes: spherical (cocci), rod (bacilli), spiral (spiralla), comma (vibrios) of corkscrew (spirochaetes). They can also exist as single cells, in pairs (e.g. Escherichia coli), chains (e.g. Streptococcus) or clusters (e.g. Staphylococcus)+.
Figure 1: Different bacterial shapes: a. bacillus, b. coccus, c. spirillum, d. spirochaete, e. vibrios, f. chain of cocci, g. cluster of cocci, h. pair of cocci, i. chain of bacilli (Source: Microbiology Society, 2016)
Bacteria reproduce via binary fission. In this process, a cell first grows twice its original size. In order to split into two identical bacteria cells, the DNA must be copied by replication enzymes first. The replication enzymes start at the origin of replication. The origin is the first part of the DNA that is copied. These origins segregate towards the opposite ends of the cell. The monomers of the protein FtsZ make a ring-like structure at the center of the cell. Then other components of the division apparatus assemble at the FtsZ ring. During the division, the cytoplasm is cleaved in two, and a new cell wall is synthesized.
The size of bacteria varies between 0.2 µm and 700 µm in diameter with the normal range of about 1-5 µm in diameter. Since bacteria are very small, they have a high surface to volume ratio (S/V ratio).9 The smaller the bacteria, the bigger the S/V ratio. Because of this, they can take up nutrients quick, grow fast and have a considerably shorter life cycle in comparison with eukaryotic cells. Because bacteria divide rapidly, there is a higher chance of mutation. This causes the bacteria to be able to adapt very quickly to environmental conditions. Therefore, bacteria have a high chance of becoming resistant to antibiotics.
In figure 2 (next page) the structure of a bacteria can be seen. Not every species has this shape, but this picture shows all the possible features a bacterium can have. Some species of bacteria have a capsule of polysaccharides to prevent the bacteria from dehydration and to protect it from phagocytosis by larger microorganisms.
The surrounding of the cell is made up of two to three layers, the interior cytoplasmic membrane, the cell wall and in some species, also the capsule. The cell wall prevents the cell from bursting when there are different levels of osmotic pressure.11 Every cell wall contains peptidoglycan. This is a construction of alternating sugars that together form a brick like wall. The cytoplasm is the place where a lot of chemical processes take place. Unlike in eukaryotes, the DNA is not stored in the nucleus, but it is spread out in the cytoplasm. The cytoplasmic membrane is a layer of phospholipids and proteins and closes the interior of bacteria and it regulates the flow of substances in and out of the cell. Not all bacteria have a flagellum. It is a hair like structure that helps the bacteria to move forward toward nutrients. A flagellum beats in a propeller-like motion. The nucleoid is where the chromosomal DNA is located, but since the DNA is spread out in the cytoplasm, the nucleoid is in this case the area of cytoplasm where the strands of DNA are found. The ribosomes are the ‘factories’ in the cell. They make sure translation of DNA is possible. Bacterial ribosomes are similar to those of eukaryotes, but they have a slight different molecular structure and composition.
A lot of bacteria have pili. These are small hair like structures present on the outside of the bacteria. These pili make sure the bacteria can attach to other cells and surfaces. Bacteria can also attach to surfaces with other features such as glycocalyx and fimbriae. Glycocalyx are polysaccharide layers and are often thick and stable like capsule or they can be loosely attached to a cell wall like a slime layer. Fimbriae have a similar function to pili but are shorter and more abundant on the cell surface.
There is also a difference between gram positive and gram negative bacteria. This difference depends on the composition of the cell wall. For both gram negative and gram positive, the plasma membrane is the most inner layer of the surrounding of the bacteria. Furthermore, both have a peptidoglycan cell wall, but this is thicker in gram positive bacteria. Gram negative bacteria have an extra plasma membrane to compensate this. On the outer layer, both types have a capsule. Gram positive bacteria are more easily treatable with antibiotics. This is due to the fact that the gram positive cell wall lacks the second layer of plasma membrane. This second layer makes it harder for antibiotics to gain entrance in the bacteria.
Figure 3: Gram positive and gram negative bacteria structure (Source: The McGraw-Hill Companies, 2016)
Teichoic acid or lipoteichoic acid is only found in gram positive cells. Both acids are attachment proteins to hold the cell wall together. They also cause an acidic charge on the cell surface. Something that gram negative cell walls only have, are porins. These porins are found in the outer membrane layer and allow specific substances to go into the cell.
A noticeable fact about gram negative cell walls is that the periplasmic space (space between the different layers) is bigger than in gram positive cell walls. Another compound that only gram negative bacteria have, are lipopolysaccharides. They stick out in the outer membrane layer. They are made of fats (lipids), proteins and carbohydrates. Lipopolysaccharides are a type of endotoxin. Endotoxins can cause inflammation, so if a patient has a bacterial infection and additionally they have fever, this was probably caused by a gram negative bacteria.
In stressful environments, the growth-rate of bacteria is reduced, due to a lack of nutrients or starvation. However, this activates the transcription of the DNA, which leads to cell division. So, it can be said that cell division a stress response is.
Skin microbiome
The skin of the human body is covered with billions of microorganisms. The mix is unique to each individual, so it is comparable to DNA. The skin is a part of the immune system and protects the body against unfamiliar substances, microbes and other harmful items entering. The microbes living on the skin, however, are not all inimical. Many microorganisms are symbiotic. They protect against invasions by other, more noxious organisms and occupy most of the skin. All organisms have their own habitat and optimum growth conditions. Consequently, different microbial species live in and on particular parts of the skin. Primarily, the skin is acidic, dry and cool, yet specific habitats are shaped by the thickness of the skin, the amount of folds and glands and the density of hair follicles. The microbiome of the skin can be grouped into two, depending on the place the microorganisms live.
The groups are named, resident and transient. The former are the microbiota that live and multiply in the epidermis and in and around hair follicles, for instance: Staphylococcus, Streptococcus, Micrococcus, Corynebacterium, Brevibacterium, Dermabacter and Malassezia. The latter are flora that live on the superficial layer, but are more convenient to removal. Moreover, they do not normally divide on the skin. Transient microbiota are often gram positive. E. coli is an example of a transient bacterium.+
Optimum growth conditions skin bacteria
In general, the four main preferences of bacteria are warm temperatures, moist, oxygen and a pH around 6.8. The optimum temperature is generally around the body temperature of humans, so approximately 37C. This makes the human body a good place for bacteria to live. However, some bacteria types prefer colder temperatures. Moist is also significant for bacterial growth. This is something all types of bacteria need, without water they die. Therefore, for example the nose and mouth of the human body, are excellent places for bacteria to live. Some bacteria only grow with the presence of oxygen and some types only grow without. Bacteria that need oxygen for growth are called aerobic bacteria and bacteria that do not need it are called anaerobic bacteria. Most bacteria types prefer a neutral environment, so a pH value that is almost the same level of the pH value of the human body. This value is around 6.8. However, some bacteria prefer a slightly more acidic or basic environment. In the preceding paragraph, a few types of bacteria on the skin were mentioned. They live on the skin because that provides the best growth conditions for these specific bacteria. The skin has different types, being dry skin, moist skin and oily skin. Each type has different types of bacteria on it. Staphylococci (S) types predominate on dry skin, corynebacteria grow the best on the moist skin and propionibacteria are most likely to grow on oily skin. All the different types are able to grow on the skin because their optimum growth conditions are present. For skin bacteria, these include a temperature of around 37C and pH value of around 7.
Antibiotics
The true meaning of antibiotics is against life and the meaning of its synonym antibacterial is against bacteria. This explains where they are used for. Antibiotics are types of medication that decrease the speed of growth or kill bacteria. They are used by people to treat an infection caused by bacteria. However, antibiotics do not cure an infection on their own. It only enhances the effect of the immune system. After all, the immune system often deals with bacterial infections on their own. Antibiotics can be divided into two groups, which are based on the effect they have. They are known as bactericidal and bacteriostatic. The former antibiotic kills bacteria. It interferes with the development of the cell wall or other components. The latter stops the cell division.
In nature, antibiotics are produced by soil microorganisms. With the antibiotic, the microbe has an advantage over others when competing for resources that keep them alive as it kills their competition. The antibiotics that are useful against bacterial infections in humans are produced by other bacteria or fungi.
In the experiment an amoxicillin suspension will be used in order to compare the ginger with. Amoxicillin is a penicillin. Penicillin is the first drug to be discovered. It interferes with the peptidoglycans of the bacteria. When a bacterium divides, small holes appear in the peptidoglycan. Normally, the walls are linked together with proteins after division. With the presence of penicillin, the transpeptidation cannot happen. As a consequence, the holes in the peptidoglycan cannot close and water flows into the bacterium, due to osmosis. In the end the bacterium explodes, as a result of the water.
Bioactive compounds of Ginger
Ginger (Zingiber officinale Roscoe, Zingiberaceae) has several bioactive compounds. “A bioactive compound is a compound that has the capability and the ability to interact with one or more component(s) of the living tissue by presenting a wide range of probable effects” (Abdelkarim Guaadaoui, 2014). The primary bioactive compound of ginger is [6]-gingerol. This is the name for 1-[4′-hydroxy-3′-methoxyphenyl]-5-hydroxy-3-decanone or C17H26O4
However, this is not the only bioactive compound, since there are 14 more discovered. These are [4]-gingerol, [6]-gingerol, [8]-gingerol, [10]-gingerol, [6]-paradol, [14]-shogaol, [6]-shogaol, 1-dehydro-[10]-gingerdione, [10]-gingerdione, hexahydrocurcumin, tetrahydrocurcumin, gingerenone A, 1,7-bis-(4′ hydroxyl-3′ methoxyphenyl)-5-methoxyhepthan-3-one, and methoxy-[10]-gingerol (Koh et al. 2009). The amount of the compound included depends on the country of origin and how the ginger is processed.
[6]-shogaol looks a lot like gingerol, since it is the dehydrated version. They are found in smaller quantities that gingerol, so therefore they are less dominant.
The bioactive compounds in ginger are also proven to have an anticancer, anti-inflammatory, anti-oxidative and antidiabetic effect.
Antimicrobial Resistance
The phenomenon antimicrobial resistance (AMR) is a natural process explained by Darwin. It starts with a few infectious microbes becoming resilient to antibiotics. This cannot be prevented as the process of getting resistant is random and lies within the DNA. When microbes divide, mutation might occur, resulting in giving the new microbes a different set of chromosomes. Now, evolution starts playing a role. Darwin explained that evolution happens due to uniqueness as well as natural selection or survival of the fittest. Which means that those with a set of DNA that fits best under the circumstances they live in, will survive the natural selection. This process can be found within every species of all four kingdoms of life, consequently within microbes.
Gram negative bacteria get resistant due to a mutation or alteration in its porins. The porins of gram negative bacteria, mentioned earlier, allow and block substances to enter the cell. When a gram negative bacteria becomes resistant to a certain antibiotic the porins are slightly changed in order to block the antibiotic. As a result, it is no longer possible for antibiotics to reach the inside of the cell; the bacterium became resilient.
When using medicines, some microbes might survive the attack, in the light of their right set of DNA. They are now antibiotic resistant. These survivors keep on dividing. When being infected with the same illness, these microbes will not die when being attacked by antibiotics.
The microbes that are resilient are as easily spread as all other microbes. This results in an increasing population which is infected with resistant bacteria. In 2014, for example, it is measured that 480,000 people develop multi-drug resistant tuberculosis each year. Not only drugs against tuberculosis, but also those against HIV and malaria start to develop resistance. When this part of the population now gets infected, it cannot be treated properly or at an high expense. However, it has more results. The decision to transplant organs or do an open surgery gets more crucial in the light of less treatment to bacterial infections.
Despite the fact that AMR is a natural process it can be influenced. Due to excessive usage of antibiotics, either not following the prescription correctly or using leftover antibiotics when feeling ill, plus the usage of antibiotics in the farming industry, enhances the process.