Bacteria

What is bacteria?

constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. They are also known to have flourished in manned spacecraft. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×10³⁰ bacteria on Earth, forming a biomass which exceeds that of all plants and animals. Bacteria are vital in recycling nutrients, with many of the stages in nutrient cycles dependent on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. In the biological communities surrounding hydrothermal vents and cold seeps, bacteria provide the nutrients needed to sustain life by converting dissolved compounds such as hydrogen sulphide and methane to energy. On 17 March 2013, researchers reported data that suggested bacterial life forms thrive in the Mariana Trench, the deepest spot on the Earth. Other researchers reported related studies that microbes thrive inside rocks up to 1900 feet below the sea floor under 8500 feet of ocean off the coast of the northwestern United States.According to one of the researchers,"You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are

Most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

There are approximately ten times as many bacterial cells in the human floragut flora, and a large number on the skin. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and some are beneficial. However, several species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy, and bubonic plague. The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem. In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the production of cheese and yogurt through fermentation, and the recovery of gold, palladium, copper and other metals in the mining sector,biotechnology, and the manufacture of antibiotics and other chemicals. as well as in as there are human cells in the body, with the largest number of the human flora being in the

Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-boundorganelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolvedevolutionary domains are called Bacteria and Archaea. from an ancient common ancestor.

 What are the different types of bacteria?

 

5 Types of Harmful Bacteria

Bacteria Type	Description
Streptococcus Pyogenes	Streptococcus Pyogenes is the causative agent of    mild sore throat and skin infections that may worsen in   certain situations to lead to life threatening infections like toxic shock syndrome and septicemia (when bacteria gain access to the blood stream). It is classified as gram positive coccus that grows mainly in chains.
Escherichia Coli	E- Coli is a gram negative bacillis as discussed previously and is considered as a causative agent of traveler’s diarrhea; however some pathogenic strains can also lead to bloody diarrhea and circulatory shock.
Vibrio Cholerae	Vibrio cholerae is the causative agent of cholera and is associated with intake of improperly cooked food or poor sanitary conditions. Vibrio Cholerae is linked to hundreds and thousands of deaths worldwide (mostly in under- developed countries) due to cholera outbreak.
Enteritis Salmonella	The most common causative agent of food poisoning throughout the world is Enteritis salmonella and can lead to serious and life threatening food poisoning, diarrhea, circulatory shock and dehydration in children. Infection can be controlled by timely intake of proper antibiotics and circulatory support.
Salmonella Typhi	Salmonella Typhi is a gram negative organism that is the causative agent of typhoid fever. It is associated with a high mortality rate after initial infection and characterized by blood diarrhea, vomiting, dehydration, fever and may lead to death if proper treatment is not instituted at the right time.

5 Types of Beneficial Bacteria

Not all the bacteria are bad for human survival. Our body is loaded with hundreds and thousands of bacteria that serve to colonize our body in order to prevent overgrowth of pathogenic elements. In addition these bacteria also serve a variety of functions. Examples of beneficial bacteria are:

Bacteria Type	Description
Lactobacillus acidophilus	Lactobacillus acidophilus exists in different parts of human body like intestine, vagina and oral cavity. It is responsible for slightly acidic pH of vagina that is helpful in preventing overgrowth of other microorganisms. In addition it is also known to boost immunity. Due to its beneficial properties, it is used in a variety of dietary products like tempeh, yogurt, miso and probiotics supplements.
Bacillus subtilis	Bacillus subtilis occurs independently in the environment around us and was first used by Nazi army to manage diarrheal illness. It helps in normalizing gut motility and metabolic functioning. It is fortified in products like yogurt, cheese, milk, ice cream and fermented soybeans.
Bifidobacterium animalis	Bifidobacterium animalis is found in the intestine of animals and humans as a normal commensal that aid in digestive process. In addition it can also be consumed in supplemental doses to improve the symptoms of constipation or irritable bowel syndrome.
Streptococcus thermophilus	Streptococcus thermophilus is classified under coccus and it has the ability to withstand a temperature of about 212 degrees Fahrenheit. Streptococcus thermophilus strengthen immunity and improves the functioning of gut. It can be obtained from cheese and other dairy products.
Lactobacillus reuteri	Lactobacillus reuteri is one of the probiotics agents that are present in maternal breast milk and becomes a permanent part of gut flora. It is also present in dietary sources like yogurt and cheese.

Types of Bacteria According to Gram Staining

Since bacterial organisms are so minute, it is impossible to view the organisms without compound microscope. In order to visualize the cellular components and to differentiate bacteria from other microbial agents, staining techniques are used by scientists to categorize different bacteria.

Gram staining is a special method that involves dying the outer covering of the bacterial cell wall that prevents it from physical and environmental trauma. On the basis of gram staining, bacteria are widely classified as gram positive (bacteria with the cell wall) and gram negative (bacteria without cell- wall).

There are a number of structural and functional variations in the bacteria of one group that helps in adapting these bacterial agents to survive in one environment where other bacteria cannot.

Bacteria Type	Description
Coccus	Coccus is rounded or spherical in shape and may occur in chains or clusters. These occurs abundantely in the environment and also as normal commensal on the human body (in nostrils, skin, oral cavity and genitals). If these pathogens grow excessively, diseases like impetigo, food poisoning and tonsillitis may occur Examples are: Staphylococcus aureus, Streptococcus pyogenes
Bacillus	Bacilli are rod shaped and may be gram positive or negative on staining. Most popular species are salmonella (the causative agent of typhoid) and E- Col (causative agent for hemorrhagic diarrhea). Gram negative as well as gram positive bacilli are well known causative agents for gastroenterological, pulmonary and cutaneous infections.
Rickettsia	Rickettsia is considered unique bacteria since it is incapable of surviving outside living organisms. Due to unstable morphological features, it is transmitted by different vector sources like ticks, fleas and mites to cause life threatening infectious diseases like Rocky mountain spotted fever and typhus.
Mycoplasma	All bacteria are characterized by a cell wall outside cell-membrane; however, mycoplasma is unique as it lacks a cell wall that is also considered a protective mechanism that makes it easier for bacteria to evade antibiotic therapies. It is causative agent for life threatening pulmonary infections and some strains may cause pelvic disease.
Spirillum	Spirillum is different from other bacterial agents as it is cork-screw shaped. It includes causative agent of Lyme’s disease (transmitted by tick bites) and syphilis.