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The coccoid or bacillary bacteria can be found in soil or wet areas. They are non- sporulating bacteria and Gram-negative . Some species are also pathogenic for humans, so their detection (e.g. with analytical profile index 20 NE) has great relevance in the diagnosis of bacterial infections.
The bacterial capsule is a large structure common to many bacteria. [1] It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases. [2] [3]
In this scheme, icosahedral capsids contain 12 pentamers plus 10(T − 1) hexamers. [14] [15] The T-number is representative of the size and complexity of the capsids. [16] Geometric examples for many values of h, k, and T can be found at List of geodesic polyhedra and Goldberg polyhedra.
For example, if E. coli is placed on an agar plate containing only glucose and lactose, the bacteria will use glucose first and lactose second. When glucose is available in the environment, the synthesis of β-galactosidase is under repression due to the effect of catabolite repression caused by glucose.
Streak plates of several bacterial species on nutrient agar plates. Nutrient agar is a general-purpose solid medium supporting growth of a wide range of non-fastidious organisms.
The total number of living aerobic bacteria can be determined using a plate count agar which is a substrate for bacteria to grow on. The medium contains casein which provides nitrogen , carbon , amino acids , vitamins and minerals to aid in the growth of the organism.
Microbial metabolism is the means by which a microbe obtains the energy and nutrients (e.g. carbon) it needs to live and reproduce.Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics.
Sucrose is particularly dangerous as a risk factor for tooth decay because Streptococcus mutans bacteria convert it into a sticky, extracellular, dextran-based polysaccharide that allows them to cohere, forming plaque. Sucrose is the only sugar that bacteria can use to form this sticky polysaccharide.