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Category: Microbiology

Experiments under the department of Microbiology

Microbiological Examination of Food Sample

Microbiological Examination of Food Sample

Introduction Microbiological examination of foods are саrrіеd out tо Ñ–dеntÑ–fу аnd rеѕtrісt hаrmful mісrоrgаnÑ–Ñ•mÑ• whісh cause ѕроіlаgе Ñ–n fооdÑ•, аnd ensure ѕаfеtу frоm foodborne diseases; аlthоugh microbiological еxаmÑ–nаtіоnÑ• do nоt dеtеrmÑ–nе аbѕоlutе safety from раthоgеnÑ• bесаuѕе tеѕtÑ• аrе done оn ѕаmÑ€lеѕ, whісh are juÑ•t a роrtіоn from thе food Ñ€rоduсtÑ•. Sеvеrаl MеthоdÑ• can be used for mісrоbіоlоgісаl examination of foods. These mеthоdÑ• Ñ–nсludе: • Culturаl techniques • Indісаtоr mеthоd • AltеrnаtÑ–vе Methods • DÑ–rесt ExаmÑ–nаtіоn • Enumеrаtіоn MеthоdÑ• Objective of…

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Isolation of Streptomycin-Resistant Mutant

Isolation of Streptomycin-Resistant Mutant

Introduction Mutation can be described as the permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosexual DNA or other genetic elements. The first step in the emergence of resistance is a genetic change in a bacterium, and there are two ways this can happen: Transfer of antibiotic-resistant genes: This is when an existing antibiotic-resistant gene transfers from one bacterium to another bacterium. Spontaneous mutation in the bacterium’s DNA: Most antibiotics work by inactivating an…

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Identification of Bacteria through Biochemical Tests

Identification of Bacteria through Biochemical Tests

1. Starch Hydrolysis Medium: Starch Agar Procedure: Obtain pure culture of the bacterium Make a single streak line of the bacterium on the starch agar Incubate at 37oC for 48-72 hours. After the end of the incubation period, iodine is added to see if the starch remains or has been hydrolysed. If the starch has been hydrolysed there will be clear zone around the bacterial growth. Note: This procedure can be used on multiple bacteria on the same agar plate, you…

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Gram Stain

Gram Stain

There are different types of stains, namely gram stain, capsule stain, endospore stain and acid fast stain. Only acid fast stain is described in this procedure. Click on the other types of staining below to learn about them. Capsule Stain Endospore Stain Acid Fast Stain Introduction Gram staining is used to differentiate bacteria based on cell wall properties. It differentiates gram positive and gram negative bacteria. Gram positive bacteria retains the primary stain (crystal violet) and appears purple under the…

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Endospore Stain

Endospore Stain

There are different types of stains, namely gram stain, capsule stain, endospore stain and acid fast stain. Only acid fast stain is described in this procedure. Click on the other types of staining below to learn about them. Gram Stain Capsule Stain Acid Fast Stain Introduction Endospore Stain is a differential stain which stains bacterial endospores or spores. Endospores may be located in the middle of the cell (central), at the end of the cell (terminal) or very close to…

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Capsule Stain

Capsule Stain

There are different types of stains, namely gram stain, capsule stain, endospore stain and acid fast stain. Only acid fast stain is described in this procedure. Click on the other types of staining below to learn about them. Gram Stain Endospore Stain Acid Fast Stain Introduction Capsule stain is a type of differential stain which selectively stains bacterial capsules. In the staining procedure, crystal violet serve as the primary stain, and all parts of the cell take up the purple…

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