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Bacteria

Bacteria are unicellular. And are found almost everywhere:> Water > Soil > Plants > Animals and Humans. Bacteria can be : > Pathrogenic and Non Pathogenic.

Growth :

Food : Saprophytic - feed on non living matter causing spoilage e.g. lactic acid bacteria destroys milk Parasitic - feed on living matter such as animals and humans causing disease e.g Staphylococcus aureus causing staph infections on the skin.

Oxygen : Aerobic : e.g Mycobaterium Tuberculosis > Anaerobic : e.g. Clostridium botulinum > Faculative: e.g. E. Coli

Temperature :

Psychrophilic : e.g. Listeria > Mesophilic: e.g. E. Coli (Most bacteria prefer this temp) > Thermophilic: e.g. Thermus auaticus > Hyperthermophilics: e.g. Thermotoga maritima

Temperature below 15° slow down growth, freezing inactivates and above 70° destroy bacteria

Moisture: Requires moisture for growth. Grow best in humid conditions and on food with a high water activity above 0.90aw e.g Bread

Ph level : Most grow best in slight acidic or neutral environments (ph 6-7).

Extreme acidic or alkaline conditions inhibit bacterial growth.

Time: Require time to grow. In ideal conditions, will double every 20 minutes