Aerobni anoksigeni fototrofi Jadranskog mora

Aerobic anoxygenic phototrophs are a newly discovered member of the bacterial community in the Adriatic Sea. During the last seven years, when we started to study these organisms, we have collected a considerable number of samples from different environments, from the coast, the estuary, and the open sea. Here we have compiled data from 34 georeferenced study sites from four studies that summarize all that is known about aerobic anoxygenic phototrophs and examine the spatial and vertical distribution and environmental factors affecting this community in the Adriatic Sea. We found horizontal and vertical influences on AAP distribution, mainly salinity, nitrates, chlorophyll a, ammonium, temperature, and soluble reactive phosphorus. Much is known about their ecology in the Adriatic, and with a new survey underway, we will expand our knowledge of their community composition and their role in carbon flux to higher trophic levels.Aerobni anoksigeni fototrofi relativno su novi član bakterijske zajednice u Jadranskom moru. U posljednjih sedam godina, od kada smo započeli proučavati ove organizme, prikupili smo znatan broj uzoraka iz različitih okoliša, obalnog, estuarnog i područja otvorenog mora. U ovom radu objedinili smo podatke s 34 georeferencirane lokacije istraživanja iz četiri studije koje sažimaju sva saznanja o aerobnim anoksigenim fototrofima te istražili prostornu i vertikalnu raspodjelu, kao i okolišne čimbenike koji utječu na ovu zajednicu u Jadranskom moru. Utvrdili smo čimbenike koji utječu na horizontalnu i vertikalnu raspodjelu AAP, uglavnom salinitet, nitrate, klorofil a, amonijeve ione, temperaturu te topljivi reaktivni fosfor. Iako se dosta zna o njihovoj ekologiji u Jadranu, aktualnim istraživanjem proširit ćemo naše znanje o sastavu ove zajednice i njihovoj ulozi u protoku ugljika prema višim trofičkim razinama

Usporedba metoda protočne citometrije i fluorescentne mikroskopije za brojenje morskih heterotrofnih bakterija

Two direct heterotrophic bacterioplankton counting methods, epifluorescence microscopy (EM) and flow cytometry (FCM) were compared using samples collected in two geographically different oceanic regions, the Adriatic Sea and the English Channel. A statistically significant correlation was found between results obtained by these two methods for samples collected in the Adriatic Sea (r =0.61, n =919, P <0.001) and in the English Channel (r =0.64, n =33, P <0.001). Samples from the Adriatic Sea showed on average 1.16 times higher values obtained by flow cytometry than val- ues estimated by epifluorescence microscopy, while samples from the English Channel showed on average a 0.74 ratio between flow cytometry and epifluorescence microscopy counts. The overall coefficient of variation for epifluorescence microscopy data for samples from the Adriatic Sea and the English Channel was 15.91% and 12.89%, respectively. The flow cytometry method had lower overall coefficient of variation value; for samples collected in the Adriatic Sea it was 3.64%, while for samples collected in the English Channel it was 1.88%Dvije direktne metode za brojanje heterotrofnog bakterioplanktona, epifluorescentna mikroskopija (EM) i protočna citometrija (FCM), uspoređene su koristeći uzorke sakupljene s dva zemljopisno različita morska područja, Jadranskog mora i Engleskog kanala. Između dvije direktne metode brojanja u uzorcima iz Jadran- skog mora (r = 0.61, n = 919, P <0.001) i Engleskog kanala (r = 0.64, n = 33, P <0.001) pronađena je statisti- čki značajna korelacija. U Jadranskom je moru metoda protočne citometrije davala u prosjeku neznatno niže rezultate u odnosu na metodu epifluorescentne mikroskopije, dok je u Engleskom kanalu broj heterotrofnih bakterija dobiven metodom epifluorescentne mikroskopije bio u prosjeku nešto veći u odnosu na protočnu citometriju. Međutim, srednji koeficijent varijacije rezultata dobivenih epifluorescentnim mikroskopom za područje Jadrana iznosio je 15.91%, za područje Engleskog kanala 12.89%, dok je protočna citometrija rezultirala nižim koeficijentima varijacije te je za uzorke iz Jadrana iznosila 3.64%, a za uzorke sakupljene u Engleskom kanalu svega 1.88%. Navedeni rezultati predstavljaju doprinos sagledavanju metode protočne citometrije kao brže, sigurnije i preciznije za brojenje bakterioplanktona u morskom okolišu

Struktura mikrobne zajednice u anhialinim špiljama na otoku Mljetu (Jadransko more)

The microbial abundances, including bacteria, viruses, and heterotrophic nanoflagellates, were determined for two anchialine caves located on the Island of Mljet (Adriatic Sea): Bjejajka Cave and Lenga Pit. Both caves are situated approximately 100 m from the coast with extensive subterranean connections to the sea, resulting in noticeable marine and terrestrial, influences. Because of the shallow settings of the studied caves, they represent habitats with a minimal light or complete darkness where photosynthesis is minimal or not possible. Thus, during the surveys there was no evidence of cyanobacterial cells in either caves, but the presence of bacteria, viruses and heterotrophic nanoflagellates (HNF) was established. Further, bacterial abundance was higher in caves in comparison to surrounding open seawater. In the surrounding seawater the predominance of the LNA group over HNA is determined, which also indicates the differences in relation to the studied caves. In fact, the dominance of HNA group of bacteria in caves together with higher total bacterial abundance indicates that the caves are of higher trophic level than the surrounding seawater. With regard to bacterial diversity, both caves had a unique makeup of bacterial populations and low diversity, with the chemolithoautotrophic Epsilonproteobacteria representing the most abundant taxonomic group. To examine the mechanisms regulating bacterial abundance in these habitats, we observed the relationship between bacteria and heterotrophic nanoflagellates (HNF) and between bacteria and viruses. The importance of predation in controlling bacteria (top down control) and, consequently, the domination of bottom up control of HNF were observed in both caves.Istraživanja abundancije mikroorganizama, uključujući bakterije, viruse i heterotrofne nanoflagelate (HNF) su provedena u anhialinim špiljama Bjejajka i Lenga na otoku Mljetu. Špilje su smještene na oko 100 m udaljenosti od obalne linije s podzemnom vezom s morem te su pod znatnim utjecajem mora kao i kopnenih staništa. S obzirom na položaj istraživane špilje predstavljaju staništa s minimalnim prodorom svjetlosti ili potpunim mrakom što ukazuje na izostanak procesa fotosinteze. Tijekom istraživanja ni u jednoj špilji nije utvrđeno prisustvo cijanobakterija odgovornih za procese fotosinteze, ali je utvrđena značajna brojnost bakterija, virusa i heterotrofnih nanoflagelata. Štoviše brojnost bakterija u špiljama je bila veća od brojnosti bakterija u okolnom moru. Jednako i odnosi HNA i LNA bakterija ukazuju na razlike između špilja i okolnog mora. U okolnom moru je utvrđena dominacija LNA bakterija u odnosu na HNA dok je u špiljama utvrđeno prevladavanje HNA bakterija što zajedno s većom ukupnom brojnošću bakterija ukazuje na viši trofički stupanj u špiljama u odnosu na okolno more. Preliminarnim ispitivanjem raznolikosti bakterija u špiljama je utvrđeno najbrojnije prisustvo kemolitoautotrofnih bakterija taksonomske skupine Epsilonproteobacteria. U svrhu studiranja mehanizama regulacije bakterijske abundancije u istraživanim su špiljama analizirani odnosi između bakterija i heterotrofnih nanoflagelata i između bakterija i virusa. Važnost predacije u kontroli bakterija (top down kontrola) je utvđena u obje ispitivane špilje

Utjecaj ekoloških čimbenika na raspodjelu dva ekotipa roda Synechococcus u obalnom moru Jadrana

Distribution and abundance of two Synechococcus ecotypes, phycocyanin-rich cells (PC-SYN) and phycoerythrin-rich cells (PE-SYN) were studied in the surface layer of the central Adriatic Sea during the 2015-2016 period. The studied area included several estuarine areas and coastal to open sea trophic gradients, covering a wide range of seawater temperatures ((11.82 - 20.75 ^oC)), salinity (4.47 - 38.84) and nutrient concentration. The abundance of PC-SYN ranged from ( 0 to 79.79 x 10^ 3 cell mL^-1) and that of PE-SYN from (5.01 x 10^3 to 76.74 x 10^3 cell mL^-1). Both ecotypes coexisted in the studied waters with PC-SYN cells dominating during spring and PE-SYN during winter and autumn. PC-SYN showed a significant positive relationship with temperature and strong positive responses to nitrogen nutrients, whereas PE-SYN positively responded to phosphate availability. The relative ratio of phosphorus availability and total inorganic nitrogen nutrients (N/P ratio) affects the spatial distribution of the two Synechococcus ecotypes.U radu je istražena raspodjela i brojnost dva ekotipa roda Synechococcus, tzv. stanice bogate fikocijaninom (PC-SYN) i stanice bogate fikoeritrinom (PE-SYN) u površinskom sloju vodenog stupca, tijekom 2015. i 2016. godine. Područje istraživanja obuhvaćalo je nekoliko estuarijskih područja te područje trofičkog gradijenta od obale prema otvorenom moru, širokog raspona temperature mora ((11.82 - 20.75 ^oC)), saliniteta (4.47-38.84) i koncentracije hranjiva. Brojnost PC-SYN bila je u rasponu od ( 0 to 79.79 x 10^ 3 cell mL^-1), a PE-SYN od (5.01 x 10^3 to 76.74 x 10^3 cell mL^-1). Utvrđeno je istovremeno obitavanje oba ekotipa na istraživanom području, s prevladavanjem PC-SYN tijekom proljeća te PE-SYN tijekom zime i jeseni. Pokazana je statistički značajna povezanost između PC-SYN i temperature te njegova jaka pozitivna povezanost s dušikovim spojevima, dok su PE-SYN stanice pozitivno odgovorile na dostupnost fosfata. Relativni omjer dostupnosti fosfora i ukupnih hranjiva dušika (N/P omjer) utjecao je na prostornu raspodjelu oba ekotipa roda Synechococcus

Dinamika prokariotske zajednice u Bokokotorskom zaljevu (Južni Jadran)

The dynamics of the prokaryotic picoplankton community were studied at six stations of three embayments in Boka Kotorska Bay from January 2010 to January 2011. The abundance of non-pigmented bacteria, high nucleic acid content (HNA) bacteria, low nucleic acid content (LNA) bacteria, bacterial production and heterotrophic nanoflagellates was determined, as well as the chlorophyll a, physical and chemical factors of the water column. It seems that freshwater input has the ability to control bacterial abundance as well as the proportion of HNA cells in bacterial community and thus the abundance of HNF cells. During the warmer seasons, in the investigated area, which is mainly oligotrophic, we found an increase in values and domination of the LNA group in the bacterial population. The dominance of the HNA group was found only during the colder seasons. Weak coupling between bacteria and HNF suggests that predation (top down control) is not dominant in controling of bacterial abundance in studied area.Raspodjela i aktivnost prokariotskog pikoplanktona u crnogorskom dijelu južnog Jadrana je studirana na šest postaja Bokokotorskog zaljeva u razdoblju od siječnja 2010. do siječnja 2011. Istraživana je brojnost nepigmentiranih bakterija, udjeli bakterija s visokim (HNA) i niskim (LNA) sadržajem nukleinskih kiselina, bakterijska proizvodnja, heterotrofni nanoflagelati (HNF) te klorofil a i fizikalno kemijski čimbenici. Utvrđeno je da unos slatke vode u istraživano područje ima utjecaja na bakterijsku brojnost, na udjele HNA I LNA grupa bakterija kao i na brojnost HNF-a. U toplijem razdoblju godine u istraživanom je području utvrđen porast i prevladavanje LNA bakterija dok je prevladavanje HNA bakterija utvrđeno u hladnijem dijelu godine. Slaba povezanost između bakterija i HNF ukazuje da predacija nije prevladavajući mehanizam kontrole bakterijske abundancije u istraživanom području

Evaluation of DNA extraction methods and direct PCR in metabarcoding of mock and marine bacterial communities

Recent advances in new molecular biology methods and next-generation sequencing (NGS) technologies have revolutionized metabarcoding studies investigating complex microbial communities from various environments. The inevitable first step in sample preparation is DNA extraction which introduces its own set of biases and considerations. In this study, we assessed the influence of five DNA extraction methods [B1: phenol/chloroform/isoamyl extraction, B2 and B3: isopropanol and ethanol precipitations, respectively—both modifications of B1, K1: DNeasy PowerWater Kit (QIAGEN), K2: modified DNeasy PowerWater Kit (QIAGEN) and direct PCR approach (P) that completely circumvents this step on community composition and DNA yield of mock and marine sample communities from the Adriatic Sea]. B1–B3 methods generally produced higher DNA yields and more similar microbial communities, but with higher interindividual variability. Each method demonstrated significant differences in a specific community structure, where rare taxa seem to play a crucial role. There was not one superior method closest to the theoretically expected mock community composition, they all demonstrated skewed ratios, but in a similar way which might be attributed to other factors, such as primer bias or 16S rRNA gene count for specific taxa. Direct PCR represents an interesting approach when high throughput in sample processing is required. We emphasize the importance of making a cautious decision about the choice of the extraction method or direct PCR approach, but even more importantly its consistent application throughout the study

Picoplankton Distribution and Activity in the Deep Waters of the Southern Adriatic Sea

Southern Adriatic (Eastern Mediterranean Sea) is a region strongly dominated by large-scale oceanographic processes and local open-ocean dense water formation. In this study, picoplankton biomass, distribution, and activity were examined during two oceanographic cruises and analyzed in relation to environmental parameters and hydrographic conditions comparing pre and post-winter phases (December 2015, April 2016). Picoplankton density with the domination of autotrophic biomasses was higher in the pre-winter phase when significant amounts of picoaoutotrophs were also found in the meso-and bathy-pelagic layers, while Synechococcus dominated the picoautotrophic group. Higher values of bacterial production and domination of High Nucleic Acid content bacteria (HNA bacteria) were found in deep waters, especially during the post-winter phase, suggesting that bacteria can have an active role in the deep-sea environment. Aerobic anoxygenic phototrophic bacteria accounted for a small proportion of total heterotrophic bacteria but contributed up to 4% of bacterial carbon content. Changes in the picoplankton community were mainly driven by nutrient availability, heterotrophic nanoflagellates abundance, and water mass movements and mixing. Our results suggest that autotrophic and heterotrophic members of the picoplankton community are an important carbon source in the food web in the deep-sea, as well as in the epipelagic layer. Besides, viral lysis may affect the activity of the picoplankton community and enrich the water column with dissolved organic carbon

MOGUĆNOSTI BRENDIRANJA TURISTIČKE DESTINACIJE NA PRINCIPIMA STORYTELLINGA

Moderni turisti putovanje počinju pretraživanjem informacija o destinaciji koju planiraju posjetiti, koje su dostupne putem interneta i društvenih mreža, ali i putem preporuka prijatelja koji su ranije posjetili određeno mjesto. Zahvaljujući pričama o turističkoj destinaciji, turisti na planirani put dolaze sa svojim željama i očekivanjima; iskusiti nešto posebno, čudesno ili edukativno. Ako turistička destinacija, smještaj ili usluga nemaju upečatljivu interpretaciju, ostat će nezapamćeni, a turist će ostati uskraćen za njihovu posebnost. Ključnu ulogu u interpretaciji ima storytelling i upravo njime se pojačava sam doživljaj. Autentičnost je još jedan koncept koji se često spominje u kontekstu destinacijskoga marketinga kroz storytelling. Cilj je istraživanja ispitati stavove i mišljenja ispitanika kako storytelling kroz autentičnost i narativno razumijevanje utječe na namjeru posjete destinacije. Rezultati istraživanja impliciraju da autentičnost priče i narativno razumijevanje kao odrednica storytellinga utječu pozitivno na namjeru posjete destinacije što se smatra temeljnim doprinosom rada

HNA i LNA bakterije u odnosu na aktivnost heterotrofnih bakterija

A one-year survey of HNA and LNA heterotrophic bacteria abundance and its relation to bacterial production was conducted in the middle and southern Adriatic. The average abundance of heterotrophic bacteria in the central and southern coastal areas of the eastern coast of the Adriatic Sea ranged from 0.24×106 to 2.39×106 cells mL-1 and in the open sea area ranged from 0.23×106 to 0.63×106 cells mL-1. Elevated average abundances were found in the coastal area of Šibenik and in Kaštela Bay. The average monthly percentage of HNA bacteria in the central and southern coastal areas investigated ranged from 21.48 to 93.18%, while in the open sea HNA ranged from 28.62 to 65.62%. The seasonal distribution in the coastal areas mostly showed simultaneously the prevalence of LNA bacteria in the bacterial community and high values of bacterial production, respectively, during spring and summer. The prevalence of the HNA group in the bacterial community was found during colder seasons together with low values of bacterial production. Exceptions are identified in the areas influenced by rivers with the highest bacterial production, where HNA bacteria were dominant in the microbial community during all four seasons. On the open sea during the periods with the highest values of bacterial production, when viewed seasonally and vertically, the water column was dominated by LNA bacteria indicating the importance of both groups of bacteria in the marine ecosystems of the waters studied.Jednogodišnje istraživanje HNA i LNA heterotrofnih bakterija u odnosu na bakterijsku proizvodnju provedeno je na području srednjeg i južnog Jadrana. Prosječna bakterijska brojnost na istraživanom obalnom području srednjeg i južnog Jadrana iznosila je od 0.24 × 106 do 2.39 x 106 st mm-1, te na otvorenom moru od 0.23 × 106 to 0.63 × 106 st ml-1. Najviše vrijednosti utvrđene su na obalnom području Šibenika i Kaštelanskom zaljevu. Prosječna bakterijska brojnost na području otvorenog mora iznosila je od 0.23 × 106 do 0.63 × 106 st ml-1. Prosječni udio HNA bakterija na istraživanom priobalnom području iznosio je u rasponu od 21.48 do 93.18%, dok je na otvorenom moru HNA iznosio od 28.62 do 65.62%. Sezonska je raspodjela tijekom proljeća i ljeta na obalnom području uglavnom pokazala istovremeno prevladavanje LNA grupe u bakterijskoj zajednici i visoke vrijednosti bakterijske proizvodnje. Prevladavanje HNA grupe u bakterijskoj zajednici utvrđeno je tijekom hladnijeg razdoblja, zajedno s niskim vrijednostima bakterijske proizvodnje. Iznimke su utvrđene na područjima najviše bakterijske aktivnosti (područja pod utjecajem rijeka), gdje su HNA bakterije prevladavale u vodenom stupcu tijekom sve četiri sezone. Na području otvorenog mora sezonska i vertikalna raspodjela je za vrijeme visokih vrijednosti bakterijske proizvodnje pokazala prevladavanje LNA bakterija. Navedeno upućuje na važnost obiju bakterijskih grupa u morskom ekosustavu istraživanog područja