All About Identifying Bacteria
Identifying bacteria is done by grouping and naming organisms based on all of their similarities. All bacteria is classified basically on the basis of cellular metabolism, cell structure, or on the differences of cell components including fatty acids, DNA, antigens, quinones and pigments.
Although these original ideas helped with identifying bacteria and classifying bacterial strands, it was still unclear if these differences were a representation of the variation between strands or distinct species. All of this uncertainty was because most bacteria lack distinctive structures as well as the lack of lateral gene transfer of unrelated species.
Due to this lateral gene transfer, many bacteria that are closely related can still have extremely different metabolisms and morphologies. Therefore, to help to overcome this uncertainty when identifying bacteria, modern bacterial techniques that are used to perform classification put a strong emphasis on molecular systematic. This is accomplished by using specific genetic techniques and sequencing genes which have not undergone much lateral gene transfer.
Traditionally, the term bacteria was used to describe all single-celled, microscopic prokaryotes but systematic show that these consist of more than just one domain. Thanks to fairly recent introductions to identifying bacteria, new classifications and identifications continue to be an expanding and constant changing field.
The Gram Stain
Developed in 1884, the Gram Stain technique of identifying bacteria is based on the cell wall's structural characteristics. Thick layers in the positive cell wall will stain purple and thin negative walls will appear pink. By using the Gram Stain method combined with morphology, bacteria becomes classified into four groups including:
- Gram-positive cocci
- Gram-positive bacilli
- Gram-negative cocci
- Gram-negative bacilli
Classification By Shape
It is believed that bacteria originally appeared over 3.5 billion years ago in even simpler shapes as it does now. Bacteria can resemble spheres, tubes, spiral corkscrews and it can even cluster into a particular pattern. The clusters are given prefixes to help identify them.
- Diplo – The cells form into groups of two.
- Strepto – The cells form into long chains.
- Staphlo – The bacteria forms into large clumps.
Culture Techniques
To promote growth and help with identifying bacteria, culture techniques are designed. These offer the ability to restrict growth in certain bacteria and promote it in others. Sterile specimens such as urine, spinal fluid and blood are cultured under specific conditions to grow possible organisms. When a pathogenic organism is finally isolated, it can then be characterized by its growth patterns, staining and morphology.
Organism Interaction
Even though bacteria may appear simplistic, complex associations can be formed with other organisms. These types of associations can be further divided by mutualism, parasitism and commensalism. Since commensal bacteria are so small they will grow as well on animals and plants like any other surface and their growth can result from sweat and warmth, of course many of these organisms are found in body odor. This is a primary reason why bacteria can spread quickly, it can live practically anywhere and survive.
There are some types of bacteria that are predatory and will consume other microorganisms. Other predators will simply attach directly to their prey to absorb and digest them.
Bacteria that form associations with other parasitic organisms are pathogens. These are often a primary cause of severe diseases and human death. Examples of such diseases include syphilis, cholera, leprosy, tuberculosis, foodborne illness, typhoid fever and tetanus. Bacterial diseases also attack agriculture such as wilts, leaf spot, fire blight, salmonella, mastitis and anthrax in farm animals. Thanks to detailed methods of identifying bacteria, the cause of diseases, how they function and treatment options has been made possible.