Microbes, an introduction. The scale of the “invisible world’; There are a thousand millimetres in a metre. There are a thousand microns (micrometres) in a millimetre, an E. coli bacterium is about a micron long – so a million of them lined up form a line a metre long, a cell of bakers yeast (a fungus) is about 10-15 microns in diameter. Some microscopic pond life is invisible to the naked eye, some are “just” visible. Viruses are very tiny, only a fraction of a micron (say 20 - 100 nanometres - billionths of a metre). Bacteria, fungi, and protozoa can be seen in a light microscope, but except for the larger protozoans, not with much internal detail. Viruses cannot be seen using a light microscope. Viruses can easily be seen using a transmission electron microscope, extensive details of cells can be analysed with an electron microscope. The “Branches” of microbiology; Bacteriologists - study bacteria, there are medical, agricultural, biotechnological specializations. Mycologists - study fungi, there are medical, agricultural, biotechnological specializations. Protozoologists, study small “animal - like” single celled organisms such as amoeba, and various disease causing parasites. Phycologists study algae. The study of lichens can also be regarded as a sub discipline of microbiology Parasitologists- a term generally used to describe those who study small animals as agents of disease (like some microscopic worms for instance) but also used to describe those who study protozoan pathogens. Immunology is often taught and researched in microbiology faculties.