Microbiology

Vitamin B12

Vitamin B12 belongs to the Vitamin-B group. Structurally, vitamin B12 is the largest among all other vitamins (B1, B2, B3, B5, B6, B7 and B9) of the same group. Vitamin B12 is also known as Cobalamin, as it contains the mineral cobalt. Methylcobalamin and 5′ deoxyadenosylcobalamin are the two metabolically active forms of cobalamin. Bacteria …

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Vitamin B6

Vitamin B6 is a water-soluble vitamin and a part of the vitamin B complex. It is named “Vitamin B6” because it comprises six vitamers, namely pyridoxine, alcohol, pyridoxal, an aldehyde and pyridoxamine (PLP and PMP). PLP (pyridoxal 5′-phosphate) and PMP (pyridoxamine 5′-phosphate) serve as the active coenzymes. Pyridoxine actively participates in protein, fat and carbohydrate …

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Production of Penicillin

The production of penicillin is practised commercially to treat various infections caused by gram-positive aerobic bacteria. Penicillin is a narrow-spectrum antibiotic or effective against many gram-positive bacteria, especially Streptococcus and Staphylococcus species. There are approximately 100 penicillins synthesized so far. For penicillin production, different strains of Penicillium (Penicillium notatum or Penicillium chrysogenum) are used.  P. …

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Flagella Staining

Flagella staining is a technique examining the presence and arrangement of bacterial flagella under the microscope. It is a specialized staining method, which requires a combination of special reagents to stain the bacterial flagella. The flagella appear as narrow appendages, which cannot be visualized by employing common stains. Therefore, the flagella staining uses mordants to …

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Negative Staining

Negative staining or Indirect staining refers to a staining technique that helps us visualize various microorganisms through light and electron microscopy. In bright field microscopy, the method of indirect staining employs liquid medium (black coloured dyes) like Nigrosin and India ink that stains the background, leaving the bacteria unstained. The negative staining technique uses a …

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Chlamydia

Chlamydia is an obligate intracellular parasite that functions as a “Large virus”. Chlamydias are entirely dependent on the host cells for energy metabolism, like viruses. However, they are true bacteria and differ from viruses by many ways. Like bacteria, chlamydia also possesses both DNA and RNA. They multiply by binary fission, whereas viruses go through …

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Difference Between Selective and Differential Media

The difference between selective and differential media is mainly due to the following factors: Intended use of the media: The purpose of both selective and differential media differs. A selective media only permits the development of particular organisms, while a differential media discerns one species of the organism from the others that are growing on …

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MacConkey Agar Media

MacConkey agar media was first introduced by a scientist named Alfred Theodore MacConkey in the year 1890s. It is primarily exercised to isolate and differentiate the non-fastidious, gram-negative bacilli belonging to the Enterobacteriaceae family. Previously, it was first considered as “Solid differential media”. But now, both liquid broth and solid culture MacConkey media preparations are …

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Pinocytosis

Pinocytosis is a kind of endocytic process. It refers to the cellular mechanism where the bilayer cell membrane invaginates to form a sac to uptake the extracellular fluids and solutes into the cytoplasm. Pinocytosis is a spontaneous endocytic process, which occurs in almost all cells. It prevalently occurs in eukaryotes. Pinocytosis, cell drinking or fluid-phase …

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Phagocytosis

Phagocytosis is a method of endocytosis. It refers to the cellular mechanism where the invagination of the plasma membrane causes internalization of the extracellular contents into the cell in the form of vesicles. Internalization is a process where a plasma membrane undergoes successive invagination to form membrane-bound vesicles, which later detach from the cell membrane …

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