The microbiome of large marine vertebrates

Abstract

Veliki morski kralježnjaci iznimno su vaţni stanovnici oceanskih ekosustava, a mogu biti domaćini velikom broju mikroorganizama. Sve više istraživanja pokazuje da je mikrobiom, skup svih gena zajednice mikroorganizama, od velike evolucijske vaţnosti za brojne višestanične organizame, a od velike važnosti je i danas, posebice za normalan rad probavnog, pokrovnog i dišnog sustava. U velike morske kraljeţnjake ubrajaju se svi morski sisavci, nekoliko gmazova (sedam vrsta morskih kornjača i jedna iguana) te ribe hrskavičnjače. Njihov mikrobiom je, unatoč sve većem broju nedavnih istraţivanja na tu temu, i dalje nedovoljno istraţen. Crijevni mikrobiom sisavaca i gmazova većinom čine bakterije koljena Bacteroidetes i Firmicutes, a manje su prisutne bakterije koljena Proteobacteria, Fusobacteria i Actinobacteria. Dobri dupin za sada je jedina poznata vrsta sisavaca čiji se mikrobiom bitno razlikuje u odnosu na ostale sisavce. Sastav crijevnog mikrobioma ovisi o načinu prehrane sisavaca i gmazova, s time da je zavisnost o prehrani izraženija kod gmazova. Zdravlje pokrovnog sustava morskih kralježnjaka ovisi o sastavu mikrobioma – u svim skupinama prisutni su geni bakterija za koje je poznato da imaju antimikrobno djelovanje. Moguće je da se na taj način održava stalan i stabilan sastav koţnog mikrobioma sisavaca i riba ili mikrobioma ljuske jajeta u kornjača. Sastav mikrobioma dišnog sustava sisavaca raznolik je te u uzorcima zdravih jedinki nisu detektirani prisutni patogeni, no vaţno je napomenuti da je ovaj organski sustav ujedno i najmanje istražen.Large marine vertebrates are important in marine ecosystems and can host a wide range of microorganisms. The microbiome is the full collection of genes of all microorganisms in a community, but often it is used as a term for all the microorganisms in a sample, not just their genes. Research that has been done in recent years shows that the microbiome had an impact on evolution of multicelular organisms. Moreover, it still plays an important role in normal functioning of digestive, integumentary and respiratory system. Large marine vertebrates include all marine mammals, several reptiles (seven species of marine turtles and one species of iguana) and cartilaginous fish (sharks and rays). Despite increasing amount of research, their microbiome has still not been sufficiently investigated. Gut microbiome of mammals and reptiles mostly consists of bacterial OTUs from phyla Bacteroidetes and Firmicutes, with less OTUs from phyla Proteobacteria, Fusobacteria and Actinobacteria. Bottlenose dolphin is (for now) the only mammal species that has significantly different microbiome from the rest of the mammals. Even though both mammals and reptiles show a correlation between gut microbiome and diet, the correlation is more pronounced among reptiles. When it comes to integumentary system, its health depends on the microbiome. All of the groups have genes specific for bacteria which produce antimicrobial substances. There is a possibility that these substances help maintain stable composition of skin microbiome or microbiome of turtle egg shells. The microbiome of respiratory system in mammals varies and there has not been any evidence of pathogen bacteria in healthy individuals. However, microbiome of this system is poorly researched and understood