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Eu bacteria belongs to the kingdom prokaryotae. This group include three main types; eubacteria is the true bacteria. The eubacteria may be anaerobic,photosynthetic or thermophillic (heat loving). Infect their most prominent characteristic is their metabolic diversity. Autotrophs and heterotrophs are intermixed within the various eubacterial phyla . although structure and function do not provide much information about their evolutionary relationships, a growing body  of ribosomal RNA analysis is adding information  rapidly. Until more data are assembled, however classification of eubacteria at the phylum level remains uncertain.
The three major groups of  archaebacteria can be defined by their cell walls. Some lack a rigid cell wall; some have a thin peptidoglycan wall without an outer lipoprotein layer; and some have a thin peptidoglycan wall that has an outer lipoprotein layer.

Eubacteria without cell walls are surrounded by a triplet layered membrane composed of lipids. These eubacteria are resistant to penicillin, because penicillin works by inhibiting the growth of the cell wall. Commonly known as mycoplasm, these eubacteria are probably the smallest (0.2-0.3µm) organisms capable of independent growth. They are of special evolutionary interest because of their extremely simple cell structure. Although certain species of mycoplasm cause diseases such as pneumonia in humans and cattle most are harmless.
Gram-positive eubacteria which have thick peptidoglycan cell walls are widespread in soil and air. Some gram-positive eubacteria produce  lactic acid in their metabolism. These are used in the preperation of products such as sauerkraut, buttermilk and yougun. Others are the source of antibiotics such as streptomycin, tetracycline and erythromycin. Still other forms endospores that enable them to survive unfavorable growth conditions.
The remaining eubacteria are gram-negative and have wide variety of metabolic styles. Although photosynthesis is widespread among the gram-negative eubacteria many photosynthetic forms are anaerobic_they do not use water in photosynthesis and thus do not produce oxygen gas. Based on the pigments present in their cells, these producers may be called green eubacteria and purple eubacteria. Many use hydrogen sulfide (HS) and release sulfur gas in photosynthesis  others use hydrogen gas (H) or compounds such as lactic acid. Like plants,however they synthesize organic compounds from carbon dioxide and convert light energy to chemical energy.
The cynobacteria or blue-green eubacteria are a photosynthetic group with structures and functions similar to those of algae and plants. Cynobacteria inhabit a wide variety of environmentals, including hot springs and under the ice of antartic lakes. They are responsible for the algal blooms on fresh water streams and lakes that have been polluted with phosphates. Some of the cynobacteria grow in colonies that can be seen with naked eyes,although individual cells are microscopic.
Cynobacteria contain cholorophyll associated with membranes, but the membranes are not organized into choloroplasts as they are in eukaryotic cells. Their photosynthesis like that of plants and algae use water and results in the release of oxygen gas. Cynobacteria are thought to be primarily responsible for the starts of oxygen revolution that changed the earth’s atmosphere,making possible the evolution of large oxygen using organisms.

There are thousand of species of cynobacteria and thousands more are existed in the ancient past. Remains of these ancient communities are found in fossil stromatolites. Stromatolites still are being produced in the salt flats along the Persian Gulf,the Bahamas,western Australia and the west coast of Mexico.
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