Vinegar
Vinegar is a food product made by acetic acid bacteria that can ferment the alcohol in alcoholic liquids to acetic acid.
Vinegar has been used for cooking and in the household and different industries due to its mildly acidic nature for many centuries. It is one of the foods together with beer, wine, bread and fermented dairy products, that is the result of fermentation by microorganisms and has been around for thousands of years. It is a mixture of acetic acid (most often 5%) and water.
The fermentation is performed usually by acetic acid bacteria, from the genus Acetobacter, from the alcohol in a variety of sources (e.g., apple cider, wine, potatoes, fermented grain). Acetobacter bacteria are Gram-negative aerobic rods. They are naturally present in environments where alcohol is being produced and can be isolated from damaged fruit, apple cider, etc. In these liquids, the bacteria form a film on the surface, since they are aerobic and need good oxygen supply.
This film, called the mother of vinegar, can be used as a starter culture of acetic fermentation in fresh alcohol liquids. Mother of vinegar can also be found in unpasteurized store brand vinegar. Acetic acid bacteria are transmitted in nature by vectors like fruit flies and Vinegar Eels.
This acetic acid fermentation needs oxygenation. If left at room temperature alcohol-containing solution with Acetobacter will be converted to vinegar in months. The industrial process can be completed within hours since air is bubbled and mixed through the solution.
Vinegar can also be an undesired product in wine production. If the temperature in the fermentation vessel is too high, the Acetobacter will outgrow the yeasts and the produced alcohol will be converted to vinegar.
Anti-biotics
Antibiotics are chemicals that kill or inhibit the growth of bacteria and are used to treat bacterial infections. They are produced in nature by soil bacteria and fungi. This gives the microbe an advantage when competing for food and water and other limited resources in a particular habitat, as the antibiotic kills off their competition.
Some Important Antibiotics from Micro-organism
| Antibiotic | Producer organism |
| Penicillin | Penicillium chrysogenum |
| Cephalosporin | Cephalosporium acremonium |
| Griseofulvin | Penicillium griseofulvum |
| Bacitracin | Bacillus subtilis |
| Polymyxin B | Bacillus polymyxa |
| Amphotericin B | Streptomyces nodosus |
| Erythromycin | Streptomyces erythreus |
| Neomycin | Streptomyces fradiae |
| Streptomycin | Streptomyces griseus |
| Tetracycline | Streptomyces rimosus |
| Vancomycin | Streptomyces orientalis |
| Gentamicin | Micromonospora purpurea |
| Rifamycin | Streptomyces mediterranei |
How do antibiotics work
Antibiotics take advantage of the difference between the structure of the bacterial cell and the host’s cell.
They either prevent the bacterial cells from multiplying so that the bacterial population remains the same, allowing the host’s defence mechanism to fight the infection or kill the bacteria, for example stopping the mechanism responsible for building their cell walls.
An antibiotic can also be classified according to the range of pathogens against which it is effective. Penicillin G will destroy only a few species of bacteria and is known as a narrow spectrum antibiotic. Tetracycline is effective against a wide range of organisms and is known as a broad spectrum antibiotic.
