Why cooperation is key in the poultry microbiome

The poultry microbiome is not simply a collection of individual, isolated microbes, rather they work together, but this may not always be positive.

Cooperation amongst its members can benefit both the microbiome and the host. (BeholdingEye | iStockphoto.com)
Cooperation amongst its members can benefit both the microbiome and the host. (BeholdingEye | iStockphoto.com)

The poultry gut microbiome is a complicated and dynamic place.  It is home to thousands of different bacterial species, more viruses, and a large group of fungal species.  Just knowing what species are present is daunting given that more of the members of the microbiome are perhaps unknown than known.  The exciting thing is understanding what all those different microbes are doing. 

Our scientific tools are expanding our knowledge rapidly and a picture is starting to emerge about what is exactly going on, and what they are doing is cooperating. 

They are cooperating in diverse groups for common goals, they are cooperating with their host for the benefit of both, and sometimes key bacteria are forcing cooperation as a way of hijacking the microbiome.

Microbiome cooperation

To cooperate, gut microbes must first communicate, and they have many different strategies to “talk” with one another.  Microbes primarily communicate through the production of specific chemical signals by one bacterium and the sensing of those signals by another, also known as quorum sensing. 

Quorum sensing is a communication tool that bacteria of the same species or even different species use to coordinate their activity, resulting in coordination between poultry gut microbes.  A form of cooperation between bacteria is the localized sharing of nutrients that are mutually beneficial, for example essential amino acids. 

Once bacterial species are talking to each other, a key example of cooperation is coaggregation into biofilms, or collections of multiple bacterial species working together in a cohesive group.  The formation of a biofilm is an important step in bacterial cooperation. Frequently, the bacteria in a biofilm can have very different activity than when outside of a biofilm - its whole is greater than its parts.  A great example of a biofilm important to the poultry intestinal tract is the collection of bacteria lining the intestinal epithelium. 

Microbes cooperating, communicating, and assembling into biofilms are hallmarks of a healthy gut microbiome, and a healthy gut microbiome also cooperates with the chicken as well. 

Microbiome, host cooperation

A great example of chicken and microbiome cooperation is complex carbohydrate digestion. 

The poultry gut does not have the ability to digest complex carbohydrates and relies on the microbiome of the ceca to break these down into energy.  Additionally, no one single bacterial species in the cecal microbiome can digest these complex carbohydrates alone. Digestion requires a diverse community of bacteria to form biofilms on the carbohydrate structures, communicating and cooperating to break them down for the chicken’s benefit.

Digestion of complex carbohydrates in the ceca is a good example of microbes cooperating for the chicken’s benefit, but some bacteria can use these cooperation methods for outcomes that are negative, at least for consumers. 

Salmonella is an example of a bacterium that can force cooperation to conceal itself from the chicken’s immune system and ultimately become a problem for consumers. 

During the colonization process it can hijack quorum sensing mechanisms and send signals back to the gut microbiome forcing cooperation that hides Salmonella from the host.  It also drives a cooperation between the gut microbiome members that dampens the host’s immune response to send an “all is well” signal.  As a result, Salmonella is effectively using cooperation to make itself invisible, and not create a benefit for the host.

Our view of the poultry gut microbiome is constantly changing as we learn more about how the many different microbes behave.  Understanding how, when, and why cooperation is taking place is an important step in modifying the gut microbiome for the benefit of efficient poultry production.

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