17 Questions
What is the purpose of Clusters of Orthologous Groups (COGs)?
Assigning functional annotations to whole genome sequences
Which structure is involved in the transmission electron micrographs of Candidatus R.magnifica?
Microvilli
How are Aposymbiotic host larvae initially infected by symbionts?
Through a permissive partner choice mechanism
What is preferentially grown on by the host resulting in one symbiont strain most often being the founder ST 1?
One symbiont strain
Which mechanism is involved in the connectivity between free-living and symbiotic Endoriftia populations?
Permissive partner choice
What is the main function of a capsule in glycocalyx?
Contributes to bacterial virulence
Why does encapsulated Bacillus anthracis cause anthrax?
Avoidance of phagocytosis
In what scenario does Streptococcus pneumoniae cause pneumonia?
When cells are non-capsulated
What role does the capsule play in Klebsiella to enhance colonization of the respiratory tract?
Prevents phagocytosis and promotes adhesion
What is the role of glycocalyx in biofilms?
Mediate adhesion to inert surfaces or living tissues
What is the characteristic feature of a slime layer in glycocalyx?
Unorganized attachment to cell walls
In the context of biofilms, what are microbial aggregates?
Clusters of different microorganisms growing together
What is the function of aldehyde fixation in studying microbial aggregates?
Facilitates visualization and study of cell aggregates
What does SEM imaging reveal about K. pneumoniae fixed with aldehydes?
Long spikes extending outwards from cell circumference
Which statement best describes the surface of K. pneumoniae in fixation containing alcian blue for 22 hr?
Covered with a thin mat-like layer interpreted as an extended slime layer
What is the main purpose of biofilm formation mechanisms?
Promote bacterial attachment to host surfaces
What is the significance of aldehyde fixation containing alcian blue in studying EPS retention?
Increased retention of EPS on the substratum
Study Notes
Clusters of Orthologous Groups (COGs)
- COGs are used to classify proteins into groups based on their sequence similarity, allowing for the identification of orthologs across different species.
Candidatus R.magnifica
- Transmission electron micrographs of Candidatus R.magnifica show a structure called a "bacteriocyte", which is involved in the transmission of symbionts to host larvae.
Symbiotic Infection
- Aposymbiotic host larvae are initially infected by symbionts through an unknown mechanism.
- The host preferentially grows one symbiont strain, ST 1, which becomes the founder strain.
Symbiotic Population Connectivity
- Gene flow is the mechanism involved in the connectivity between free-living and symbiotic Endoriftia populations.
Glycocalyx and Capsule
- The main function of a capsule in glycocalyx is to provide protection from the host's immune system.
- The capsule of encapsulated Bacillus anthracis helps to evade the host's immune system, leading to anthrax.
- Streptococcus pneumoniae causes pneumonia when it infects the lungs and bloodstream.
- In Klebsiella, the capsule enhances colonization of the respiratory tract by preventing the host's immune system from recognizing the bacterium.
Biofilm Formation
- The role of glycocalyx in biofilms is to create a protective matrix for the microorganisms to adhere to and form a complex community.
- A characteristic feature of a slime layer in glycocalyx is its loose, diffuse structure.
- Microbial aggregates are clusters of microorganisms that adhere to each other and to a surface, forming biofilms.
- Aldehyde fixation is used to study microbial aggregates, and it involves cross-linking proteins to preserve the structure of the biofilm.
- SEM imaging of K.pneumoniae fixed with aldehydes reveals a thick, fibrous glycocalyx.
- When fixed with alcian blue, the surface of K.pneumoniae appears rough and fibrillar.
- The main purpose of biofilm formation mechanisms is to provide protection and a means of adherence for the microorganisms.
- Aldehyde fixation containing alcian blue is significant for studying EPS retention in biofilms.
Explore the scanning electron microscope (SEM) images of K.pneumoniae showing absence of glycocalyx features, presence of long spikes extending outwards, rugae, and circumferential spikes. Images are taken after fixation with aldehydes and alcian blue staining.
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