There are two major domains of bacteria: Archaebacteria and Eubacteria. Archaebacteria are an older, more ancient form of bacteria that have adapted to survive some of the harshest conditions on Earth. Eubacteria evolved from Archaebacteria. They are found just about everywhere except for harsh environments. Some bacteria are photosynthetic and the rest are heterotrophic.
Arachaebacteria like to live in places on Earth that are considered inhospitable by other organisms. They can be found in extreme conditions that help explain why it is believed these organisms are the predecessors of life. Salt lakes with concentrations that would shrivel other organisms, hot springs that would boil others are commonplace for these bacteria. It is believed that these bacteria once inhabited early Earth. As early Earth’s conditions were extremely harsh and volatile, these bacteria had no choice but to adapt or become extinct. In the end, these bacteria did survive and likely gave rise to all other branches of bacterial life and beyond.
Eubacteria come in two forms: aerobic and anaerobic. Anaerobic bacteria cannot survive in an oxygenated environment. A commonly known type of anaerobic bacteria is Enteritis Salmonelosis, which causes food poisoning. These bacteria are usually Gram-negative (refers to their protein coat) and are harder to kill than other bacteria. The protein coat of a bacteria are important in treatment. The type of antibiotic that is selected to treat a bacterial infection is dependent upon whether it is gram positive or gram negative. Different antibiotics treat gram positive and gram negative. If the wrong one is given, it will fail to kill the offending bacteria.
Aerobic bacteria are everywhere. They multiply exponentially and can be beneficial and harmful. Their three main shapes are bacillus, spirila and coccus. Some of these bacteria are harmless, some are beneficial and others are disease-causing pathogens. Harmless bacteria exist in everyday lives. Humans have Staphlococcus on their skin that does not harm them but does fight off other possibly pathogenic bacteria. Some bacteria are used to make foods. The live active cultures in yogurt are bacteria. Sauerkraut is another example of a food created through the use of bacteria.
Pathogenic bacteria get all of the fame as they are most feared and well known due to the diseases they cause. These bacteria proliferate quickly, are highly heterotrophic and can cause secondary infection. Some examples of pathogenic bacteria are Streptococcus and Esterechia coli. Both of these bacteria have the ability to cause serious infection in their hosts.
