L9 Microbial Interactions, Signalling and Specialised Metabolism Flashcards
What is a biofilm
A community of microbes attached to a surface
What is chemotaxis
Cell movement along a gradient sensing favourable conditions
Explain how bacteria sense a gradient and move towards an attratctant
Periods of flagellum movement counterclockwise towards attractant and the clockwise motion to stop forward motion
Period of tumbling to assess gradient
Why is it beneficial to be a biofilm
Harder to be consumed or attacked
What can affect biofilm formation
Nutrition needs to be plentiful
Physical conditions (pH, iron conc, temp, oxygen)
Co-colinisation
Do interconnections of the periplasm have to be in one species
No, different species can form interconnections with one another e.g. Horizontal gene transfer, share of mRNA
What is intercellular SENSING
Information gained from environment
Physical conditions, change vaused by other organisms
What is intercellular SIGNALLING
Signalling between cells via small organic compounts
Taken up by cell and cause change, involve specific signalling pathways and gene expression
Is Quorum sensing a sensing or signalling prcess
Signalling
What is Quorum sensing
Secretion of small molecules within a bacterial population which cause a coordinated behaviour when a threshold (quorum) is reached
When dental plaque is removed, why does the same composition of species return
Chemical interdependence formed during sugar metabolism
Can the metabolites of one species impact others
Yes
What impacts can secondary / specialist metabolites have on another species
Phenotypic or intracellular
What are actinomycetes
High GC content, gram positice soil inhabitants
What causes the earthy smell when it rains
Actimomycetes rekeases volatile geosmin from dead cells
What are some life forms of Actinomycetes beside soil saprotrophs
Pathogenic
Plant endophytes
What are Streptomyces
Type of actinomycetes
Filamentous spore former
Where are streptomyces found and what is their metabolsim
Soil obligate aerobes, heterotrophic saprotroph
Why are streptomyces mistaken for fungus
They form mycelia so growth form looks similar to fungus
What is an arthropsore
Structure that branches off streptomyces mycelia
Released into atmosphere to find new food source
What is important about the secondary products of streptomyces
Produce many antibiotics
What are possible roles of antibiotics in nature
Killing off competitors
Incidental biochemistry (pathway has to produce something)
Communication (but can they reach these concentrations in nature)
What is hormesis
The most plausable reason for antibiotics in nature - they have a dual effect
High conc - the antibiotic kills
Low conc - it acts as a signalling molecule
How many species of lichens are there
20,000
