Bacterial glycocalyx: Slime layers and capsules
By: Tami Port MS
From the cell wall inward, most bacteria are much alike. The bacterial cell wall and materials adhering to its surface are the main ways in which we differentiate one species or strain from another. Some bacteria have an additional layer outside of the cell wall...
Mannitol salt (MSA) bacterial growth medium
By: Tami Port MS
When bacterial cultures are grown in a laboratory environment, they are essentially captives, part of a microbial zoo dependent on people to provide the proper environment for their survival and growth. A nutrient-rich media is required to grow bacteria in the lab. Mannitol Salt Agar...
Selective bacterial growth media: MacConkey's and mannitol salt
By: Tami Port MS
A growth medium (plural: media) is a mixture of nutrients, moisture and other chemicals that bacteria need for growth in a laboratory environment. Media can be solid, such as Jell-o-like agar that is poured into the bottom half of a Petri dish, or media can...
Acellular infectious agents: Comparison of viruses, viroids and prions
By: Tami Port MS
Infectious disease can result of cellular organisms, such as bacteria (prokaryotes), from eukaryotes (cells like ours) or from nonliving infectious agents such as viruses, virioids and prions. Here is a summery of the different types of acellular, nonliving infectious agents.* What Is a Cell...
Lysogenic replication of bacteriophage viruses
By: Tami Port MS
Bacteriophages are a type of virus that prey upon bacterial cells. The reproduction of bacteriophages always involves death of the infected bacterium, when the viruses burst out or lyse their prokaryotic host cell. Bacteriophages reproduce by commandeering a bacterium and ultimately killing it. But sometimes...
Positive gram stain reaction of bacteria
By: Tami Port MS
Gram + bacteria stain purple due to the chemistry and structure of their peptidoglycan cell wall. Here's how Gram staining identifies Gram-positive organisms.* The Gram Stain *In the 1800's, Christian Gram, a Danish bacteriologist, developed a technique for staining bacteria that is still widely...
Negative gram stain reaction of bacteria
By: Tami Port MS
Gram- bacteria stain pink due to the location of cell wall peptidoglycan and an external LPS membrane. Here's how Gram staining identifies Gram negative organisms.* Christian Gram's Stain *In the 1800's, Christian Gram, a Danish bacteriologist, developed a technique for staining bacteria that is...
Lytic replication of bacteriophage viruses
By: Tami Port MS
Bacteriophages are a special type of virus that exclusively infects bacterial cells. Here's how they recognize, take over and ultimately kill their host bacteria.* Viral Host Recognition *Most viruses infect only a certain type of host. This specificity is due to the affinity of...
Gram stain reaction of bacteria
By: Tami Port MS
Gram staining involves the application of a series of dyes that leaves some bacteria purple (Gram +) and others pink (Gram -). Here's how the Gram stain works.* From Spontaneous Generation to Germ Theory *Through most of recorded history, illnesses that we now recognize...
By: Tammy T
Extremophiles are organisms that are capable of living, growing and reproducing under extreme conditions such as hot springs, hydrothermal vents, salt lakes, polar deserts and other stressful environments. They are a relatively recent discovery in the field of microbiology considering scientists only found out about...

 

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