Bacteriology

Bacteriology, or the study of bacteria, is a subdiscipline of microbiology. Bacteriology encompasses many fields, including medicine, technology, agriculture, business, biology and sanitation. Bacteriology's beginnings date back to around 1000 b.c.e. and methods of food preservation used by the Chinese, who worked to prevent food from spoiling, though they did not know the exact cause.

The modern foundation for bacteriology is credited to the 19th-century botanist Ferdinand Cohn, who was the first to describe a method of organizing microorganisms. His methodology of taxonomic classification is still used today, although it has been refined many times.

Bacteria are divided into over 3,000 known species, but it is estimated that this represents less than 1 percent of all the species available in nature. Bacterial taxonomy is based on morphology and genetic structure, as well as environmental characteristics. Recently, bacteriology has expanded to include the recently discovered archaea. Archaea are also single-celled organisms, but they are believed to have existed before what we classify today as bacteria, having branched from the evolutionary tree before bacteria.

Bacteria are defined as single cell, prokaryotic microorganisms. The name bacteria (or singularly bacterium) was derived from the Greek word βακτηριυ, meaning “small stick.” Bacteria have three distinct recognizable regions: the cell membrane, the cytoplasmic region, and the appendages. The cell membrane region has two distinct functions. First, the general morphology of the bacteria, whether spherical, rod, or spiral/bent rod is determined by the cell membrane. Second, the molecular structure of the membrane, whether a monolayer or bilayer, affects the properties of the cell. The cytoplasmic region contains all genetic materials and all structures used to process food, conduct respiration, and make energy. The appendages are critical in the development of movement. They range from short filamentous sweepers to long tails and flagella. The plethora of morphologies including cocci- (spherical) and rod-shaped can range in size from 0.5 to 5 micrometers (10-6 meters).

Bacteria can live in virtually every environment on earth, from deep-sea thermal vents to the subzero temperatures in the Antarctic. Bacteria are found in foods, in the air, in the soil, in water, and on human skin. Each environment carries its own obstacles for bacteria to overcome, and they have evolved to have characteristics that allow them to thrive in such extreme conditions. Bacteria in the soil must combat fluctuating alkalinity, relatively low amounts of oxygen, and even other bacteria. Bacteria living in air developed spores to adapt to a constantly changing environment. Those living in marine environments have responded to the low levels of light and oxygen by developing different methods for respiration and energy production. Bacteria living on food and the human body are extremely susceptible to other microorganisms and the natural defenses of the host, like the high acidity found on human skin.