Bacteria. is only one side of their story.

Bacteria.Although they’ve developed quite a notorious reputation over the years for thecause for a variety of deadly diseases, this is only one side of their story. Although many may not believe it, bacteria are actually our more of our friendthan foe.

Very soon you’ll find out how they are fundamental for human health, severalfood processes and biotechnology. 1)   Bacteria’sRole in Human Health The human body routinely harbors about 1014 bacteria– ten times more bacteria than there are cells 1. Although they’ve developedquite the reputation for causing diseases, there are actually many beneficialand essential bacteria that live both on our skin and inside our bodies.In fact, there are less than 100 species of bacteria that purposely causeinfectious diseases in humans, but more than several thousand species that existsymbiotically in/on us 2. These bacteria that live in and on humans are partof the microflora. Let’s take a closer look at exactly how these bacteriapromote health in humans. Beneficial Bacteria on the Skin Thebacteria that live on skin are usually either commensal (relationshipwhere one organism benefits without affecting the other) or mutualistic(relationship where both organisms benefit) 3 & 4. Note that although the mutualistic/commensal do not usually causedisease, in the rare case when there is an imbalance of them, they can alsoturn pathogenic.

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As seen in Image 1, these bacteria can live on the skin’s surface, pores andeven sweat glands 5. The skin flora’s main role for humans is to act as a line ofdefence. They usually prevent pathogenic organisms (those that can causedisease) from colonizing the skin surface by:1.     Competing against pathogens for nutrients that are provided by thehost 6.

Since commensal and mutualistic microflora compete with competing invaders forthe host’s limited resources, it makes it much more difficult for invadingmicrobes to survive and cause a disease.2.     Secreting or creating chemicals such as fatty acids and bacteriocinsthat kill invading microbes 6 & 3.  3.     Stimulating the skin’s immune system so that white bloodcells such as lysosomes can destroy any pathogens on the skin 6. One example of a bacteria on our skin that protects us is Propionibacteriumacnes. This rod-shaped bacterium usesour body’s sebum to inhibit the growth of invading pathogens 5. It does thisby converting the triglycerides found in sebum into free fatty acids; hencelowering the pH of skin 5 & 7.

This contributes to the skin’s acidic pHof approximately 5, limiting the growth of many common bacteria that can turn pathogeniclike Staphylococcus aureus and Streptococcus pyogenes 5 & 8.   Another similar example of amutualistic skin bacterium Pseudomonasfluorescens 9. By producing the antimicrobial substance pseudomonic acid,it not only prevents bacterial infections such as impetigo, but also inhibitsthe growth of fungus species such as Candida albicans – the fungus that can cause thrush 9& 10. To give you an idea of how effective this bacterium is at controllingand killing pathogens that attempt to invade humans, it is actually currentlyused to create a commercial antibiotic known as Mupirocin 9 & 10.

Beneficial Bacteria in the BodyInsidethe body, the gut contains the largest numbers of bacteria 11. The gut florais constructed during the infancy years of life and play important roles innutrition, digestion and immune function 12. These roles include but are notlimited to 12 & 13: ·       Aids in the digestion of food such as proteins and dietary carbohydrates·       The gut microbiota helps with the synthesis of essential compoundssuch as Vitamin B12, Vitamin K and biotin·       Some intestinal flora work to protect the body against certainkinds of infection by inhibiting the growth of harmful organisms Without the proper balance of gut flora, not only can digestiveissues such as bloating occur, but inflammatory and autoimmune conditions suchas type 1 diabetes may also arise 14.

One example of a beneficial group of microflora are theLactobacillus bacteria. They are a genus of rod-shaped bacteria that have theextraordinary ability able to produce vitamin K 15. This is important becausevitamin K is essential to the formation of proteins, blood coagulation, and bonerepair/formation 16. Vitamin K deficiency can lead to issues such as bonefractures, bruising and irritable bowel syndrome 16. Furthermore, Lactobacillus produces an enzyme that is capable of breakingdown lactose (a sugar found in milk) into lactic acid. This not only enables humansto digest dairy products, but the production of lactic acid also disrupts the outer membrane of bacterial cell walls 12. Thisassists in inhibiting the growth of pathogenic microbes such as E.

Coli, Salmonellaand Candida albicans in the vaginal andurinary tracts; hence reducing the possibility of infections 12. Bacterial gut flora such as Lactobacillus is so important to humanhealth that the relatively new probiotic industry – which focuses onintroducing beneficial microflora into your body using foods and supplements –is projected to be worth US$64 billion by 2023 17.2)   Bacteria’sRole in Food ProcessingAlthough it is common to hear that we don’t want any bacteria inanything we eat, it may be surprising to hear that they are actually involvedin the production of many fermented foods. DairyMany dairy products are just milk products that havebeen fermented over time.

They almost always require a “starter culture” toconvert the sugar in milk – known as lactose – into lactic acid 18. In cheese for example, the starting culture is usually a combination of lactococci and lactobacilli19. Changing the mixture of the starting culture will alter the cheese’s acidity,moisture, aroma, taste and texture 20. In addition to this, adding other strains of bacteria while thecheese ripens will also alter the final product. For example, Swiss Cheese iscreated by adding Propionibacterium Shermanii 19 & 20. The bacteria will convert the aceticacid in milk into propionic acid and carbon dioxide; giving the Swiss cheeseits distinctive sharp taste 20.

 MeatFermentedmeats such as salami, pepperoni, and dried ham also require starter cultures tomake 18. Not only are lactic bacteria used as starters, but there are a widevariety of other bacteria that can be used to ripen the surface of the meats, altertheir flavour, and prolong shelf life 18. For example, through the production of lactic acid, Pediococcus and Lactobacillusare two bacteria added to increase the acidity of cured meats whilst Micrococcusis used to reduce spoilage by converting the nitrate in the meat into nitrite 21.

 3)   Bacteria’sRole in Modern Day Biotechnology Major scientific discoveries such as the structure of DNA have exponentiallyincreased our knowledge about biotechnology 22. This has led to a variety ofnew applications for bacteria in modern day advancements and improved standardsof living for many.InsulinDiabetesis a disease that occurs when one cannot create insulin properly. This means thatthe glucose that one consumes is not able reach used as energy by the body’scells 23. This leads to issues such as excessive hunger, headaches anddizziness 24. Now, up until the 1980s, the only treatment for diabetes was insulinthat was extracted from the pancreas of animals such as cows and pigs 25. However,thanks to bacteria, we now have a much more sanitary and reliable method forproducing insulin.

Insulin production now occurs via the following method 26& 27:1.     A working gene that codes for insulin creation is extracted from ahuman 2.     It is combined with the DNA of a bacteria (known as a plasmid) toform recombinant DNA3.     This recombinant DNA is inserted into the bacteria (Usually E.coli)4.     The bacteria will reproduce with itself, creating more insulin recombinantbacteria5.

     The recombinant bacteria will then begin using the gene to producehuman insulin. The insulin is then collected. If anyone wantsto make sure that they understand the above method, please feel free to have alook at Image 2, or watch the following video animation on creating insulinrecombinant bacteria: https://www.                       CRISPRImaginea technology that enables humans to remove any gene that could turn into amutation. CRISPR-Cas9 is a precise genome editing tool that us to cut andpaste target segments of DNA.  It worksby attaching a piece of ribonucleic acid (RNA) to the target area, which actsas a guide telling the Cas9 enzyme where to cut.  The snipped sequence can then be repairedwith a favourable mutation, allowing us to tailor specific attributes.While this mechanism to perform miraculous genetic enhancements isavailable, progress in humans is limited by our relatively exiguous knowledgeof genetics; however, this is certain to change.At this rapid rate of technological advance, it is only a matterof time before genetic diseases become irrelevant, and genetically enhancedfood becomes commonplace.


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