20.500.12556/RUL-183776 Spremembe v sestavi in presnovni aktivnosti mikrobioma meduz ob prehodu iz zdrave v starajočo populacijo gostitelja Changes in the composition and metabolic activity of the jellyfish microbiome during the transition from a healthy to an aging host population Zadnje raziskave kažejo, da mikrobiom predstavlja ključen in neločljiv del skoraj vsakega organizma. Z gostiteljem tvori t. i. holobiont, v katerem mikrobi aktivno vplivajo na fiziologijo, razvoj in zdravje organizma. Kljub mnogim raziskavam mikrobioma morskih organizmov pa želatinozni zooplankton oziroma meduze kot holobionti ostajajo slabše raziskani. Za meduze so značilna sezonska množična pojavljanja, ki pomembno vplivajo na ekološke in biogeokemijske procese v morskem okolju. Za boljše razumevanje, napovedovanje in morebitno uravnavanje teh pojavov je ključno preučiti dejavnike, ki vplivajo na populacijsko dinamiko meduz, med katere bi lahko spadal tudi njihov mikrobiom. V nalogi smo zato raziskali sestavo in presnovno aktivnost mikrobioma meduz med prehodom iz zdrave v starajočo se populacijo gostitelja. Izbrali smo dva predstavnika želatinoznega zooplanktona: rebračo Mnemiopsis leidyi in klobučnjaško meduzo Aurelia aurita s.l. Vrsti se med seboj filogenetsko razlikujeta ter imata različne življenjske cikle, biokemijsko sestavo in sezonsko dinamiko množičnega pojavljanja v severnem Jadranu. Osredotočili smo se na bakterijska rodova Pseudoalteromonas in Vibrio, saj je predhodno sekvenciranje gena za rRNA 16 S bakterijskih izolatov pokazalo njuno prevlado v mukusu meduz, njuno pomembnost pa potrjujejo tudi predhodne raziskave. Z uporabo fluorescenčne in situ hibridizacije (FISH) in epifluorescenčne mikroskopije smo ugotovili, da je gostota mikrobov v mukusu meduz večja kot v okoliški morski vodi, pri čemer prevladujeta rodova Pseudoalteromonas in Vibrio. Med preučevanima vrstama meduz nismo zaznali večjih razlik v gostoti mikrobov, smo pa pri obeh opazili upad njihove gostote ter spremembe v zastopanosti omenjenih bakterijskih rodov med razvojem populacije gostitelja. S pristopom BONCAT in klik kemijo smo dodatno potrdili metabolno aktivnost bakterij rodov Pseudoalteromonas in Vibrio v mukusu rebrače Mnemiopsis leidyi. Pomemben vpliv na sestavo in delovanje mikrobioma meduz bi lahko imela biokemijska sestava gostitelja, za katero smo sklepali, da se s staranjem organizmov spreminja. Analiza koncentracij proteinov in aminokislin v meduzah, vzorčenih v različnih fazah razvoja populacije, je pokazala, da se med razvojem populacije spreminjajo tako skupne koncentracije proteinov in aminokislin kot tudi zastopanost posameznih aminokislin. Rezultati kažejo, da mikrobiom predstavlja dinamičen in potencialno pomemben dejavnik v življenju in propadanju meduz ter da se njegova struktura spreminja sočasno z razvojem populacije in biokemijsko sestavo gostitelja. Čeprav so potrebne dodatne raziskave na večjem številu osebkov, predstavljajo ugotovitve pomemben prispevek k razumevanju vloge mikrobioma v življenjskem ciklu meduz. V nadaljnjih raziskavah bi lahko podrobneje obravnavali vpliv sprememb biokemijske sestave gostitelja na strukturo mikrobioma ter vlogo mikrobnih skupnosti pri množičnih pojavih želatinoznega zooplanktona v morskih ekosistemih. Recent research shows that the microbiome represents a crucial and inseparable component of nearly every organism. Together with the host, it forms a holobiont, in which microbes actively influence the physiology, development, and health of the organism. Despite increasing studies on marine holobionts, gelatinous zooplankton, particularly jellyfish, remain understudied as hosts. Jellyfish are characterized by seasonal population blooms that significantly influence ecological and biogeochemical processes in marine environments. To better understand and potentially manage these events, it is essential to investigate factors affecting jellyfish population dynamics, among which the microbiome may play an important role. In this study, we investigated the composition and metabolic activity of the jellyfish microbiome during the transition from a healthy to a senescent host population. Two representatives of gelatinous zooplankton were selected: the comb jelly Mnemiopsis leidyi and the scyphozoan jellyfish Aurelia aurita s.l. These species differ phylogenetically and exhibit distinct life cycles, biochemical composition, and seasonal bloom dynamics in the northern Adriatic Sea. We focused on the bacterial genera Pseudoalteromonas and Vibrio, as prior sequencing of the 16 S rRNA gene from bacterial isolates revealed their dominance in jellyfish mucus, consistent with previous studies. Using fluorescence in situ hybridization (FISH) and epifluorescence microscopy, we demonstrated that microbial density in jellyfish mucus exceeds that in ambient seawater, with Pseudoalteromonas and Vibrio as dominant genera. No major differences in total microbial density were observed between the two species; however, both exhibited a decline in microbial density and shifts in the relative abundance of the selected bacterial genera during host population development. Using the BONCAT approach combined with click chemistry, we confirmed the metabolic activity of Pseudoalteromonas and Vibrio populations in the mucus of Mnemiopsis leidyi. Host biochemical composition, which may change during aging, could influence microbiome composition and functioning. Analysis of protein and amino acid concentrations in jellyfish sampled at different population stages showed changes in both total concentrations and relative amino acid composition. Our results indicate that the microbiome represents a dynamic and potentially important factor in both the life and decay of jellyfish, and that its structure changes simultaneously with host population development and biochemical composition. Although additional studies on a larger number of specimens are required, these findings provide an important contribution to understanding the role of the microbiome in the jellyfish life cycle. Future research should further investigate how changes in host biochemical composition influence microbiome structure and clarify the role of microbial communities in jellyfish blooms within marine ecosystems. holobiont želatinozni zooplankton mikrobiom fluorescenčna in situ hibridizacija (FISH) biokemijska sestava holobiont gelatinous zooplankton microbiome fluorescent in situ hybridization (FISH) biochemical composition true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-06-18 14:50:03 2026-06-18 14:50:27 2026-06-19 04:14:15 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 25485 Azbe_Klara_-_Spremembe_v_sestavi_in_presnovni_aktivnosti_mikrobioma_meduz_ob_prehodu_iz_zdrave_v.pdf Azbe_Klara_-_Spremembe_v_sestavi_in_presnovni_aktivnosti_mikrobioma_meduz_ob_prehodu_iz_zdrave_v.pdf 1 DC66A8A9AB9C4D549B937317A79E6B6E eeec1ec6bc8fc5b6d833c1771a445b82a164d8377eb508a7694362e547e52ee1 3a83791e-6b14-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=235956 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0