Microorganisms support life of multi-cellular organisms providing them with nutrient supply, defense, and other functions essential to their physiology. Available studies show that most of marine organisms possess a stable core microbiome, reflecting the unique microbial taxa characteristic of a host or environment, aiding our understanding of species-specific functions. At the same time, microbiomes vary in composition across hosts, influenced by host-specific microbial selection in different environmental and biological conditions. It has also been hypothesized that microbiomes can help them to face extreme environmental conditions and can enhance their survival in new environments. Therefore, understanding diversity and functions of microbiomes in multicellular organisms and their interactions with surrounding environment is fundamental. In this thesis we aimed at expanding knowledge on environmental and animal-associated microbiomes (in terms of composition and functioning) when subjected to extreme conditions (i.e., extremely cold temperatures) and outside their original habitat (i.e., alien species). To do so, we investigated the microbiome of two Antarctic krill species (Euphausia superba and Euphausia crystallorophias), two of the most invasive alien fish species (Pterois miles and Lagocephalus sceleratus) in the Mediterranean Sea and two species of native and invasive ascidians (Pyura dura and Styela plicata, respectively). The findings revealed that microbiome diversity was similar within each group but composition varied significantly between species and sampling areas, highlighting the roles of host and environment as primary diversity drivers. Moreover, core microbiomes were identified for all holobionts studied, consisting of bacterial taxa essential for host survival. Anoxybacillus was prevalent in Antarctic krill, likely aiding cold adaptation, while Vibrio, Photobacterium, and Pseudoalteromonas dominated invasive fish microbiomes, potentially supporting their success in the Mediterranean. Similarly, Methyloceanibacter and Endozoicomonas genera were ubiquitous in S. plicata, likely enhancing resilience to stressors like pollution and competition. These core taxa were largely absent from the surrounding environment in krill and ascidians, suggesting vertical transmission, whereas fish microbiomes showed partial exchange with their environments. The results of this thesis underscore the predictive value of microbiomes in assessing the range expansion of alien species and emphasize the importance of microbiome studies in understanding marine organism adaptation and acclimatization under global change.
I microrganismi supportano la vita degli organismi multicellulari fornendo loro nutrienti, difesa e altre funzioni essenziali per la loro fisiologia. Studi disponibili mostrano che la maggior parte degli organismi marini possiede un microbioma core stabile, che riflette i taxa microbici unici caratteristici di un ospite o di un ambiente, aiutandoci a comprendere le funzioni specifiche delle specie. Allo stesso tempo, i microbiomi variano nella composizione tra gli ospiti, influenzati dalla selezione microbica specifica dell’ospite in diverse condizioni ambientali e biologiche. È stato anche ipotizzato che i microbiomi possano aiutare gli organismi ad affrontare condizioni ambientali estreme e migliorare la loro sopravvivenza in nuovi ambienti. Pertanto, comprendere la diversità e le funzioni dei microbiomi negli organismi multicellulari e le loro interazioni con l’ambiente circostante è fondamentale. In questa tesi abbiamo mirato ad ampliare la conoscenza sui microbiomi ambientali e associati agli animali (in termini di composizione e funzionamento) quando soggetti a condizioni estreme (ad esempio, temperature estremamente fredde) e fuori dal loro habitat originale (ad esempio, specie aliene). Per fare ciò, abbiamo studiato il microbioma di due specie di krill antartico (Euphausia superba e Euphausia crystallorophias), due delle specie ittiche aliene più invasive (Pterois miles e Lagocephalus sceleratus) nel Mar Mediterraneo e due specie di ascidie native e invasive (Pyura dura e Styela plicata, rispettivamente). I risultati rivelano che la diversità del microbioma risulta simile all'interno di ciascun gruppo, ma la composizione varia significativamente tra specie e aree di campionamento, evidenziando il ruolo dell’ospite e dell’ambiente come determinanti primari. Inoltre, sono stati identificati microbiomi core per tutti gli olobionti studiati, costituiti da taxa batterici essenziali per la sopravvivenza dell’ospite. Anoxybacillus è stato trovato prevalente nel krill antartico, con un probabile ruolo nell'adattamento di questi organismi alle condizioni di freddo estremo del loro habitat, mentre Vibrio, Photobacterium e Pseudoalteromonas dominano i microbiomi dei pesci invasivi, supportando potenzialmente il loro successo nel Mar Mediterraneo. Allo stesso modo, i generi Methyloceanibacter ed Endozoicomonas sono ubiquitari in S. plicata, con un probabile ruolo nella resilienza a stress come l’inquinamento e la competizione. Questi taxa "core" sono risultati in gran parte assenti dall’ambiente circostante nel krill e nelle ascidie, suggerendo una trasmissione verticale, mentre i microbiomi dei pesci mostravano uno scambio parziale con i loro ambienti. I risultati sottolineano il valore predittivo dei microbiomi nel valutare l’espansione dell’areale delle specie aliene e enfatizzano l’importanza degli studi sui microbiomi per comprendere l’adattamento e l’acclimatazione degli organismi marini di fronte ai cambiamenti globali.
The microbiome of marine organisms and its connections with the environment
SIMONCINI, NICOLA
2025
Abstract
Microorganisms support life of multi-cellular organisms providing them with nutrient supply, defense, and other functions essential to their physiology. Available studies show that most of marine organisms possess a stable core microbiome, reflecting the unique microbial taxa characteristic of a host or environment, aiding our understanding of species-specific functions. At the same time, microbiomes vary in composition across hosts, influenced by host-specific microbial selection in different environmental and biological conditions. It has also been hypothesized that microbiomes can help them to face extreme environmental conditions and can enhance their survival in new environments. Therefore, understanding diversity and functions of microbiomes in multicellular organisms and their interactions with surrounding environment is fundamental. In this thesis we aimed at expanding knowledge on environmental and animal-associated microbiomes (in terms of composition and functioning) when subjected to extreme conditions (i.e., extremely cold temperatures) and outside their original habitat (i.e., alien species). To do so, we investigated the microbiome of two Antarctic krill species (Euphausia superba and Euphausia crystallorophias), two of the most invasive alien fish species (Pterois miles and Lagocephalus sceleratus) in the Mediterranean Sea and two species of native and invasive ascidians (Pyura dura and Styela plicata, respectively). The findings revealed that microbiome diversity was similar within each group but composition varied significantly between species and sampling areas, highlighting the roles of host and environment as primary diversity drivers. Moreover, core microbiomes were identified for all holobionts studied, consisting of bacterial taxa essential for host survival. Anoxybacillus was prevalent in Antarctic krill, likely aiding cold adaptation, while Vibrio, Photobacterium, and Pseudoalteromonas dominated invasive fish microbiomes, potentially supporting their success in the Mediterranean. Similarly, Methyloceanibacter and Endozoicomonas genera were ubiquitous in S. plicata, likely enhancing resilience to stressors like pollution and competition. These core taxa were largely absent from the surrounding environment in krill and ascidians, suggesting vertical transmission, whereas fish microbiomes showed partial exchange with their environments. The results of this thesis underscore the predictive value of microbiomes in assessing the range expansion of alien species and emphasize the importance of microbiome studies in understanding marine organism adaptation and acclimatization under global change.File | Dimensione | Formato | |
---|---|---|---|
Tesi_Simoncini.pdf
embargo fino al 28/04/2029
Dimensione
7.13 MB
Formato
Adobe PDF
|
7.13 MB | Adobe PDF |
I documenti in UNITESI sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/20.500.14242/202966
URN:NBN:IT:UNIVPM-202966