Vibrios are of special importance too in the life cycle of bivalve molluscs,
representing constant and also intermittent associate partnerships as commensals
and sometimes as pathogens. Vibrios have shown a multifaceted nature when
associated with mussels or oysters, with several pathogenic species in the second
case while only a limited number of species are pathogenic for mussels. Oysters and
mussels have developed different mechanisms to control Vibrio infections and, in
return, vibrios possess countermeasures to avoid the bivalve immune system.
Bivalves also display selectivity in their organ-associated microbiota reflecting an
adaptation to the respective tissue. Gill symbionts are commonly found in molluscs
that survive inside the eukaryotic cells in specialised vesicles. This association
provides benefits to the host in the form of organic compounds in otherwise harsh
and potentially poor environments, such as deep-sea marine vents, allowing the
adaptation of the mollusc to these habitats.
The holobiont and hologenome concepts redefine what constitutes the animal
individuality by stating that host and their symbiotic microbes are complex units of
biological organisation susceptible to ecological and evolutionary pressures
(Bordenstein and Theis 2015). From our understanding of their complexity, the
study of ecological interactions and implications in the lifestyle of host and symbiotic organisms represents a milestone for scientists. The integration of new sequencing technologies, such as metagenomic and transcriptomics techniques, and genetic
tools will provide more accurate answers and new perspectives to get the whole
picture of these natural cooperative interactions.
Acknowledgements Dr. Jesús L. Romalde acknowledges the support of MINECO (Ministerio de
Economía Industria y Competitividad, Spain) (Projects AGL2016-77539-R, AGL2013-42628-R,
and AGL2010-18438) that funded his research on molluscan microbiota.
Aide lasa
24 Coevolution of Molluscs and Their Microbes
521
representing constant and also intermittent associate partnerships as commensals
and sometimes as pathogens. Vibrios have shown a multifaceted nature when
associated with mussels or oysters, with several pathogenic species in the second
case while only a limited number of species are pathogenic for mussels. Oysters and
mussels have developed different mechanisms to control Vibrio infections and, in
return, vibrios possess countermeasures to avoid the bivalve immune system.
Bivalves also display selectivity in their organ-associated microbiota reflecting an
adaptation to the respective tissue. Gill symbionts are commonly found in molluscs
that survive inside the eukaryotic cells in specialised vesicles. This association
provides benefits to the host in the form of organic compounds in otherwise harsh
and potentially poor environments, such as deep-sea marine vents, allowing the
adaptation of the mollusc to these habitats.
The holobiont and hologenome concepts redefine what constitutes the animal
individuality by stating that host and their symbiotic microbes are complex units of
biological organisation susceptible to ecological and evolutionary pressures
(Bordenstein and Theis 2015). From our understanding of their complexity, the
study of ecological interactions and implications in the lifestyle of host and symbiotic organisms represents a milestone for scientists. The integration of new sequencing technologies, such as metagenomic and transcriptomics techniques, and genetic
tools will provide more accurate answers and new perspectives to get the whole
picture of these natural cooperative interactions.
Acknowledgements Dr. Jesús L. Romalde acknowledges the support of MINECO (Ministerio de
Economía Industria y Competitividad, Spain) (Projects AGL2016-77539-R, AGL2013-42628-R,
and AGL2010-18438) that funded his research on molluscan microbiota.
Aide lasa
24 Coevolution of Molluscs and Their Microbes
521