Bacteria are among the micro-organisms responsible for food poisoning, list and discuss the condition favorable for the growth and multiplication of bacteria in food.

Bacteria are the simplest and smallest micro –organism that is capable of destroying or poisoning food directly and easily. Bacteria love temperatures that resolve around the temperature of our body (36.6⁰c,98.6^of ).Holding products at higher temperatures (greater than 130⁰ f,54^oc) restricts the growth of bacteria.

Increasing temperatures over 60⁰ c (140⁰f) will start killing them. Most bacteria need oxygen (aerobic), others thrive without it (anaerobic). All of them hate cold, and round 32^of, (o⁰c) they become lethargic and dormant when the temperature drops lower keeping them at lower temperatures does not kill them, but only stops them from multiplying. Once the conditions are favorable again, they will wake up and start growing again.

Some bacteria tolerate the presences of salt better than others and we take advantage of this when curing meats. Others bacteria e.g. clostridium botulinum are able to survive high temperatures because they form spores.

What are spores?

Spores are special cells that envelop themselves in a protective shell and become resistant to harsh environmental condition. Once the condition favored them, the cells return to their actively growing state.

Given condition favorable for bacteria to multiply and grow can double up in number every 20minutes. In refrigerator their number will also grow and double up in 12 hrs.

The under listed are the factors or condition that are favorable for the growth and multiplication of bacteria in food.

1.      Water

2.      Food /nutrients

3.      Oxygen

4.      Temperature

5.      P^H

1.      WATER: - Bacteria need water to dissolve food they use for energy and growth. Water allows the food to get into the cells, is used for the many chemical reactions necessary for life and growth, and allows waste products to escape.

2.      FOOD / NUTRIENTS: - All bacteria require energy to live and grow. Energy sources such as sugars, starch, protein, fats and others compounds provide the nutrients.

3.      OXYGEN :- Some bacteria require oxygen to grow (aerobes) while others can grow only in the absence of oxygen (anaerobes). However, many bacteria grow under either condition and they are facultative anaerobes.

4.      TEMPERATURE:- Bacteria in general are capable of growing over a wide range of temperatures and are usually classified according to the temperature at which they grow. Psychotropic bacteria are those that are capable of growing at 32⁰f -45⁰f but their optimum is from 68⁰f to 86^of. They cause spoilage in foods stored under refrigerator. Several pathogenic bacteria are psychotropic – yersina and listerina mesophilic bacteria.

Most bacteria are capable of growing at about 60^of and belong in this group. Most pathogenic bacteria grow at these micro- organisms grow at higher temperature such as 110⁰f – 150⁰f.

Temperature is most widely used method of controlling bacteria growth. Bacteria grow slowly at temperatures below 45⁰f and thermal destruction occurs at temperature danger zone – between 45⁰f and 140⁰f many bacteria are controlled.

5.P^H :- P^H is a measure of acid or alkali in a product. It is indicated on a scale from 0 to 14, with seven being neutral. If the P^H value is below 7, the food is classified as alkaline. Most bacteria grow well at neutral p^h, but many can reproduce in a p^h range from 4.5-10.0.

In conclusion, although each of the major factors listed above plays an important role, the interplay between the factors ultimately determines whether a micro-organisms will grow in given food. The results of such interplay are unpredictable, as poorly understood synergism or antagonisms may occur. An advantage is taken of this interplay with regard to preventing the outgrowth of c.botulinum. Food with P^H of 5.0. in addition many micro-organisms does not need to multiply in food to disease.