Bacteria | Microbiology - Biology IB23

Bacteria

Bacteria

Prokaryotic cells which are around 1-10 micrometers and can be either gram-negative or gram-positive.

Possibly the first living organisms on Earth, appearing 3,8-3,5 billion years ago.

Bacillus

Rod-Shaped Bacteria

Coccus

Round Bacteria

Spirochaete/Spirillus

Squiggly Bacteria

Diplo-Bacteria

In-Pair Bacteria

EX: Diplococcus, Diplobacillus

Strepto-Bacteria

In-Chain Bacteria

EX: Streptococcus, which causes strep-throat.

Staphylo-Bacteria

In-Clump Bacteria

EX: Staphylococcus which can normally be found on skin, but is poisonous if invaded into blood.

Tetanus

Contracted by bacteria from soil that enters wounds.

Tuberculosis

Airborne disease which affects breathing and lungs.

Salmonella

Contracted by raw chicken and eggs.

Botulism

Contracted by improperly canned foods.

Syphilis

A curable STD.

Bubonic Plague | Yersinious Pestis

Spread by rats.

Positive-Gram Bacteria

Thicker cell wall, and able to be killed off by antibiotic penicillin.

Gram-Negative Bacteria

Thinner cell wall, and aren’t able to be killed off by antibiotic penicillin.

Gram-Staining Procedure

1. Small bacteria sample is collected onto a Petri dish - smear. It’ll be heat-fixed so the bacteria fixes itself to the slide, ensuring they aren’t removed during the staining processes.

2. The primary stain, crystal violet, will be applied to the dish first staining the cells with purple colour.

3. Iodine acting as the mordant will be added to the primary stain to trap it in the cells.

4. Ethanol/acetone will be used as a decolourizer and interacts with the cells’ lipids. The negative-gram bacteria’s membrane will be lost resulting in colourlessness, while the thick cell wall of the gram-positive bacteria will continue to stay purple.

5. Safranin/carbol fuchsin will be added lastly, keeping the gram-positive bacteria purple and turns the gram-negative pink.

Decomposition

Bacteria is used to recycle nutrients back to soil so producers can use them while also getting rid of waste.

Food Industry

Preservations of food can be made possible with bacteria to make them last longer, like cheese, yogurt, sauerkraut and kimchi.

Biotechnology

Genetically modified bacteria can help produce proteins such as insulin needed by diabetics, or clean up pollution and oil spills.

Symbiotes

Bacteria can outcompete harmful organisms but also able to produce vitamin B and K.

Facultative Anaerobes

- Grows both anaerobically and aerobically, but greater growth in presence of oxygen.
- Presence of enzymes SOD and catalse allows toxic oxygen to be neutralized.

Obligate Anaerobes

- Disappears in presence of oxygen.
- Lacks enzymes to neutralize toxic forms of oxygen.

Obligate Aerobes

- Oxygen is required for it to grow.
- Presence of enzymes SOD and catalse allows toxic oxygen to be neutralized.