Bacteria: Harmful and Beneficial Aspects

Bacteria, being microorganisms, can have both harmful and beneficial effects. Harmful bacteria are known to cause diseases in plants and animals, and can also have damaging effects in various other ways. For example:

a) Parasitic bacteria can attack plants, leading to diseases such as fire blight in apple and pear trees, and ring disease in potatoes, as well as the formation of crown galls.

b) Many human diseases are caused by bacteria, which can have detrimental effects on human health.

c) Some bacteria produce acids that can convert wine to vinegar, causing spoilage.

d) Bacteria can also cause the decay of wood, leather, fabrics, and other materials.

e) Bacterial decomposition can spoil food materials.

Examples of diseases caused by bacteria in humans include tuberculosis, which leads to swelling or nodule growth in the lungs or other parts of the body; tetanus, a condition characterized by prolonged muscle contractions, particularly in the jaw and other areas; cholera, which causes intense diarrhea; leprosy, a disease that attacks the nerves and leads to loss of sensation in the affected areas of the skin; typhoid fever, which involves the invasion of major organs in the body; meningitis, an inflammation of the membranes of the brain and spinal cord; sore throat, an inflammation of the respiratory tract; and whooping cough, an infection of the respiratory tract that causes periodic spasms of the larynx followed by a long, growing inspiration.

 

Methods for Controlling Bacterial Food Spoilage

There are several methods that can be employed to control food spoilage caused by bacteria, including:

Sterilization: This process involves killing microorganisms, including bacteria, by heating food to temperatures ranging from 12 to 126°C under pressure for 12 to 90 minutes.

Pasteurization: This method involves heating food to a temperature that is sufficient to kill nonspore-forming bacteria, such as milk, which is pasteurized by heating it to 71°C for 15 seconds or 62°C for 32 minutes. This process does not alter the taste of the milk.

Low Temperature: Food can be preserved for several days by keeping it at temperatures ranging from 10 to 15 degrees Celsius, as is commonly done with eggs, milk, vegetables, cheese, and meat.

Freezing: Food can be frozen at temperatures ranging from -10 to -18°C for several weeks to several months, as is often done with meat and vegetables.

Drying: The growth of bacteria can be inhibited by adding preservatives, such as acids to lower the pH, salt or sugar to increase their content and reduce the available water for bacterial growth, and chemicals like potassium metabisulphite. This method is commonly used to preserve pickles, candies, jam, and bread.

Radiation: Food can also be sterilized by exposing it to gamma radiation, as is done with meat and potatoes.

In conclusion, bacteria can have both harmful and beneficial effects, and their harmful effects can be controlled through various methods to prevent food spoilage and diseases in humans and plants.