Social Behaviour in Marine Microbes

Social Behaviour in Marine Microbes

• Microbes exhibit complex social behaviours, not unique to humans or complex animals.
• Social interactions observed in bacteria include communication and decision-making, cheating, bullying, helping, suicide, aggression, and families helping each other.
• Understanding these interactions can help develop advanced biotechnology and medicinal applications.
• Social behaviour in bacteria and viruses has evolved due to advantages in cooperation. These led to a selective advantage.
• Social networks originated in bacteria.
• Bacterial behaviour includes biofilm formation, extracellular matrix, differentiation into producers, cell chaining, and biofilm maturation.
• The image shows complex microbial community structure such as spores, sporulating cells, D-amino acids, polyamines, motile cells, and differentiation into matrix producers and cell chaining.

Lecture Outline

• Key questions posed by the lecturer regarding social interactions in microbes, including the types, their biological mechanisms, and their applications in biotechnology/medicine.

Behaviour Types

• Complex communication/decision making.
• Cheating.
• Bullying
• Helping others
• Suicide
• Aggression
• Families helping each other
• Selfish gene.

Evolution

• Microbial behaviours are not unique to humans and even other complex animals.
• These behaviours can be observed in bacteria and even viruses.
• During evolution, the advantage of working together was clear, leading to selective advantages.
• Social networks developed in bacteria.

Quorum Sensing (Revision)

• Gram-positive bacteria use peptides for quorum sensing, which is density-dependent.
• Gram-negative bacteria use small molecules (like AHLs) and also has density-dependent quorum sensing. Many examples include Vibrio fischeri.
• Quorum sensing in gram-negative organisms involves a transcriptional activator protein (R protein) and an autoinducer (AHL) molecule produced by the autoinducer synthase.

Cell-Cell Communication by Airborne Signals

• Ammonia signalling induces biofilm formation.
• Ammonia also induces antibiotic resistance.

Bacterial Olfaction

• Bacteria can sense their environment using olfaction, analogous to higher organisms.
• Bacillus licheniformis respond behaviorally to volatile molecules like ammonia in a coordinated way.

Biofilm Induction

• Bacillus licheniformis DSM13 exhibits biofilm formation in microtitre plates when cultured in different media (MSgg, LB). Biofilm formation is dependent on distance between wells in plates.

Ammonia and Microbial Interactions

• Spent supernatant from DSM13 cultures, grown in MSgg media over 39 hours, affects pH in surrounding plates.
• Different concentrations of ammonia, result in different levels of effect.

Nanowires

• Microbes have electrically conductive pili that can be used to communicate between cells and as a terminal electron acceptor.
• Cells may communicate by using these pili.
• Information sharing, and biotechnological applications are considerations surrounding this function.

Conclusions

• Microbes demonstrate complex social behaviours.
• Quorum sensing and olfaction are examples of these mechanisms.
• Understanding these systems helps to combat microbes by hindering their ability to communicate.
• Bacteria have already developed sophisticated methods for interacting.