Investigating the effect of four antibiotic agents on gram positive and gram negative bacteria.

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Investigating the effect of four antibiotic agents on gram positive and gram negative bacteria

Aim

To find out how four antibiotic agents- Penicillin G, Streptomycin, fresh garlic and odourless garlic- effect gram-positive and gram-negative bacteria. The two different bacteria used will be Bacillus subtilis and Escherichia coli. After transferring the antibiotics to the bacteria I will be able to look for zones of inhibition in the bacteria where the antibiotic agents were placed.

Scientific knowledge & understanding

Bacteria are prokaryotes, which means they are organisms that lack a nuclei and are a lot smaller in volume than Eukaryotes (animals, plants, fungi & protoctists), on average only 0.5-5 m in diameter. Bacteria are a lot simpler in their structure. Structures always found in bacteria include a cell wall, plasma membrane, cytoplasm, ribosomes and circular DNA. Other structures that are present in some bacteria can be shown in the diagram below.

Bacteria can be found almost anywhere as different types have different optimum temperatures e.g. Thermophilic bacteria work best at temperatures above 45 C whereas Psychrophilic bacteria grow best at temperatures below 20 C. Bacteria can also be identified by their shape. Spherical bacteria are called cocci,