Micro-organisms Chapter 20

Microbiology Microbiology is the study of micro-organisms. There are 3 main types of micro-organism: Viruses, Bacteria Fungi.

Viruses A virus is a small piece of genetic material such as DNA surrounded by a protein coat. All Viruses are parasites, i.e. they live on or in living organisms. Viruses cause disease such as common cold, influenza and chicken pox. They also cause measles, mumps, German measles, polio, AIDS, and rabies. Foot and Mouth in cattle and sheep and distemper in dogs are also caused by viruses.

A typical virus replication cycle 1918 influenza virus. The Spanish flu pandemic lasted from 1918 to 1919. Older estimates say it killed 40–50 million people while more recent research suggests that it may have killed as many as 100 million people, or 5% of the world's population in 1918. A child with chicken pox

Bacteria Bacteria are bigger than viruses. Most are saprophytes (live on dead matter). Antibiotics such as Penicilin and Streptomycin can kill bacteria

Antonie van Leeuwenhoek, the first microbiologist and the first person to observe bacteria using a microscope. Typical Bacterium

Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells

Fungi Fungi are parasites or saprophytes. Examples of Fungi include yeast, mushrooms and bread mould

Clockwise from top left: Amanita muscaria, a basidiomycete; Sarcoscypha coccinea, an ascomycete; black bread mold, a zygomycete; a chytrid; a Penicillium conidiophore

Stilton cheese veined with Penicillium roqueforti Film-A diseased peach

Ringworm is a fungal infection of the skin Ringworm is a fungal infection of the skin. It usually produces a ring-shaped lesion which appears to clear in the center. The edges of the lesion may be slightly raised and often itch. Central clearing can be seen in some of the infected areas on the leg of this person

Soil micro-organisms. Bacteria and fungi break down dead organic matter and turn them into Humus. Humus contains plant minerals essential for healthy growth.

Biotechnology Biotechnology is the use of organisms or their enzymes to manufacture useful products. Industrial products of biotechnology include alcohol and cheese. Medical products of biotechnology include antibiotics and Insulin.

To show the presence of micro-organisms in Soil Apparatus used Petri dish containing nutrient Agar, sample of fresh soil,sample of sterile soil, Marker 1. Spread small bits of soil(sterile and fresh ) across the top of the nutrient Agar petri dishes. 2. Place in an oven at 30 C 3. After 2-3 days examine the petri-dishes. Result Colonies of bacteria will appear on the plate containing the fresh soil. No growth on the other plate.

Agar plate with bacteria(strep)