Cell-cell communication

Biofilms

Organisms attach to substrate through extracellular matrix

Superorganisms which influence habitat, nutrient cycling etc

Quorum sensing

Swimming microbes attached to a surface

Cell secretes slimy matrix of polysaccharide

Cells release inducer molecules which accumulate

Quorum of cells accumulate for sufficient qunatiites of inducer molecules

Pseudomonas has lung biofilms in some types of pneumonia

Signal producing bacteria can cheat and use others signals

Biolumenescence, biofilm formation,

DNA conjugation and transfer in Enterococcus, viruses

Criteria

Correct signal receptor

Signal transduction

Signal-producing bacteria nearby

Virulence

Expression of a virulent phenotype by pathogenic bacteria

pCF10 plasmid transfer

Recipient cells secrete high concentrations of oligopeptide pheromone cCF10

Donor cells upregulate aggregation substance Asc10

Horizonatal gene transfer

Allows bacteria to acquire new traits through single event

Occurs through

Transduction

Transformation

Conjugation

Bacteriophage mediates transfer process following attachment to bacterial surface

Naked DNA taken from external environment by bacteria that are competent for transformation

Plasmid mediates its own transfer between bacterial cells

Encodes machinery for transfer in its own genome

Two types

Generalised

Specialised

Productive replication, degradation of host DNA

Packaging of viral DNA

Rare packaging of host DNA

Up to 50% of phage heads have host DNA

Lysogeny

Induction

Rare excision error

Productive replication

Lambda bacteriophage

Packaging of hybrid DNA

Transformation with DNA fragments

Double-stranded DNA