Examples in gram negative bacteria are 1) bioluminescence production by Vibrio fisheri 2) Pseudomonas aerogionosa synthesis and release of virulence factors 3) Conjugal transfer of genetic material by Agrobacterium tumefaciens and 4) antibiotic production by Erwiniacarotovora and Pseudomonas aureofaciens . Gram positive bacteria also regulate activities by quorum sensing often using an oligopeptide pheromone signals. Good examples are mating in Enterococcus faecalis, competence induction in Streptococcus pneumonia, and stimulation of sporulation by Bacillus subtilis , and production of many toxins and other virulence factors by Staphylococcus aureus. Another important function of quorum sensing is to promote the formation of mature biofilms by the pathogen, Pseudomonas aeroginosa , as it may play a role in cystic fibrosis. Quorum sensing is an example of what might be called multicellular behaviour in that many individual cells communicate and coordinate their activities to act as a unit. Other examples of such complex behaviour are pattern formation in colonies and fruit body formation in the Myxobacteria.

 

Fig. 8. Quorum sensing

 

REFERENCES:

Text Books:

1. Jeffery C. Pommerville. Alcamo's Fundamentals of Microbiology (Tenth Edition). Jones and Bartlett Student edition.

2. Gerard J. Tortora, Berdell R. Funke, Christine L. Case. Pearson - Microbiology: An Introduction. Benjamin Cummings.

Reference Books:

1. Lansing M. Prescott, John P. Harley and Donald A. Klein. Microbiology. Mc Graw Hill companies.