Effect of Environmental Conditions on <i>Escherichia coli</i> Survival in Seawater

We investigated separate and simultaneous effect of temperature, salinity and solar radiation, as well as bacterial strain and origin on Escherichia coli (E. coli) survival in seawater in experimental conditions. The experiments were carried out by placing the bottles filled with seawater of different salinity (15.0, 30.0 and 36.5 psu) and contaminated by bacterial cultures in three light‐protected air incubators set to different temperatures (6, 12, 18 and 24°C), or by placing the bottles in plastic containers filled with water of controlled temperature and exposing them to direct solar light. In experiments in the dark, two typed and two wild E. coli strains were tested. The mean T90 values were 33.55 h for E. coli ATCC 8739, 42.50 h for E. coli ATCC 35218, 72.8 h for E. coli originating from seagull feces and 278.6 h for E. coli originating from sewage, indicating differences between survival abilities among strains. The effect of temperature on T90 was significant only in seagull E. coli at 36.5 psu and sewage E. coli at 30.0 psu and was positive. The effect of salinity was significant only in seagull strain and also was positive. No interactive effect of temperature and salinity was recorded. Experiments in the presence of solar radiation, carried out with two ATCC E. coli strains, demonstrated its dominate harmful effect on bacterial cells, reducing T90 of both strains to 0.30–0.82 h for E. coli ATCC 35218 and 0.31–5.93 h for E. coli ATCC 8739. Within the ultraviolet A (UVA) and photosynthetically active radiation (PAR) spectrum of solar radiation, the wavelengths of 320–360 nm were found as most bactericidal. By comparing survival of cultivated E. coli cells to those in natural seawater samples, significantly higher survival E. coli cells in natural seawater samples was found

La influencia de la materia orgánica y pigmentos de fitoplancton sobre la distribución de bacterias en sedimentos de la Bahía de Kaštela (mar Adriático)

Bacterial abundance, biomass, volume and morphological diversity were studied in sediments collected in the eastern Adriatic Sea (Kaštela Bay) in order to investigate their relationship with changes in environmental parameters. To asses the changes in the investigated parameters on a temporal scale and between sediment layers, the sediment samples were collected monthly in 2002 with a piston corer from the sediment surface to a depth of 10 cm. The concentrations of organic matter (OM), chloroplastic pigment equivalents (CPE), chlorophyll a (chl a) and phaeopigments (PHAEO) were used as indicators of substrate concentrations in sediments. Sediment depth was a significant factor influencing the distribution of bacterial abundance, biomass and volume. Granulometric properties of the sediment had no effect on the distribution of bacteria. Bacterial abundance, biomass and volume were strongly related to the indicators of substrate concentrations on both scales. The accumulation of labile OM in deeper layers also had a profound effect on the size and structure of bacteria. High amounts of OM and the low proportion of labile organic fraction (CPE; chl a and PHAEO) indicate that this environment acts as a sink for accumulation of detrital material.La abundancia, biomasa volumen y la diversidad morfologica bacteriana fueron estudiadas en sedimentos recogidos del este del mar Adriático (bahía de Kaštela) con el objeto de investigar su relación con los cambios de diferentes parámetros ambientales. Para establecer los cambios de los parámetros investigados a escala temporal y entre capas de sedimentos, las muestras de sedimento fueron recogidas mensualmente durante 2002, con un corer de pistón desde la superficie del sedimento hasta la profundidad de 10 cm. La concentración de materia orgánica, pigmentos cloroplastídicos equivalentes (CPE), clorofila a (chl a) y feopigmentos (PHAEO) fueron utilizados como indicadores de la concentración de sustrato en el sedimento. La profundidad del sedimento era un factor significativo en la influencia de la distribución del número de bacterias, biomasa y volumen. Las propiedades granulométricas del sedimento no tenían efecto sobre la distribución de bacterias. La abundancia, la biomasa y el volumen bacteriano estaban fuertemente relacionadas con los indicadores de sustrato en ambas escalas. La acumulación de la materia orgánica lábil en las capas más profundas tambien tenían un gran efecto sobre el tamaño y la estructura bacteriana. Una alta cantidad de materia orgánica y baja proporción de la fracción orgánica lábil (CPE; chl a y PHAEO) indica que estos ambientes actúan como sumideros para la acumulación de material detrítico

Volume, abundance and biomass of sediment bacteria in the eastern mid Adriatic Sea

Bacterial abundance, biomass, cell volume, and morphological diversity were studied in sediment samples collected from the coastal area of the eastern mid Adriatic Sea. Samples from the topmost 10 cm of sediment were taken monthly from January to December 2002. The number of bacteria varied from 3.54 x 109 cells g–1 in July to 8.08 x 109 cells g–1 in September. Biomass was lowest in May (78 µg C g-1) and highest in December (378 µg C g-1). The volume of the bacteria varied markedly with season, fluctuating from 3.87 x 108 µm3 g-1 in May to 3.12 x 109 µm3 g-1 in December. Cells with a volume smaller than 0.1 µm3 accounted for the largest number of bacteria (62%) and cocci comprised 93% of these cells. More than 80% of all rod cells had a volume smaller than 0.5 µm3. The majority of filamentous cells (63%) belonged to the 0.32 µm3 volume class. Rodshaped cells were dominant in terms of volume (45-72%) and biomass (42-72%) and cocci in terms of abundance (52-70%). Cells smaller than 0.5 µm3 made up 88-94% of the bacteria and 68-84% of the biomass in the summer and 6-44% of the bacteria and and 21-81% biomass in the winter

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

Zastupljenost i specijacija žive u jadranskom planktonu, školjkašima i ribi – pregled

This article presents an overview of available research on mercury speciation in the most studied biota of the Adriatic Sea as a specific biogeochemical subunit of the Mediterranean. We present current knowledge about mercury concentration, speciation, spatial distribution and temporal changes in plankton, bivalves and fish from the Adriatic Sea. Results from mercury speciation studies in marine organisms are used to describe the extent of mercury bioaccumulation in the Adriatic Sea. Mercury biogeochemical cycle in the Adriatic is characterised by increased mercury concentrations from the water column, through plankton, bivalves and smaller fish to predator fish species. Although the Adriatic Sea has the highest mercury concentration in the whole Mediterranean Sea, fish species at the higher trophic levels have similar mercury concentrations everywhere in the Mediterranean, indicating incomplete understanding of the transfer mechanisms of mercury from seawater to upper trophic levels. As consumption of (contaminated) food is the main route of human exposure to mercury, it is of great importance to understand the influence of mercury contamination in the Adriatic Sea.Ovaj članak predstavlja pregled dostupnih istraživanja o specijaciji žive u najproučavanijoj bioti Jadranskog mora kao posebne biogeokemijske podjedinice Mediterana. Predstavljamo postojeće znanje o koncentraciji žive, specijaciji, prostornoj raspodjeli i vremenskim promjenama u planktonu, školjkašima i ribi Jadranskog mora. Rezultati studija o specijaciji žive u morskim organizmima su korišteni za opis razdiobe bioakumulacije žive u Jadranskom moru. Biogeokemijski ciklus žive u Jadranu karakterizira povećanje koncentracije žive od vodenog stupca, preko planktona, školjkaša i manjih riba do predatorskih ribljih vrsta. Iako Jadransko more sadrži najviše koncentracije žive u cijelom Mediteranu, riblje vrste na višim trofičkim razinama imaju slične koncentracije žive posvuda u Mediteranu, ukazujući na nepotpuno razumijevanje prijenosnih mehanizama žive iz morske vode na više trofičke razine. Budući da je konzumiranje (kontaminirane) hrane glavni put ljudske izloženosti živi, od iznimne je važnosti razumijevanje utjecaja kontaminacije živom u Jadranskom moru

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

Akumulacija indikatorske bakterije Escherichia coli u dagnji (Mytilus galloprovincialis) i kamenici (Ostrea edulis) u eksperimentalnim uvjetima

The simultaneous effects of temperature and salinity on the accumulation of Escherichia coli (E. coli) in mussels (Mytilus galloprovincialis) and oysters (Ostrea edulis) were studied under experimental conditions with different concentrations of E. coli in seawater. The experiments were carried out in 3000 L tanks, within the natural range of temperature (12oC, 18oC and 24oC) and salinity (32 psu and 37 psu) in the coastal areas of the Adriatic Sea. Within the achieved range of E. coli concentrations in seawater (4x10-4.6x103 CFU/100 ml), bacteria accumulated rapidly in the bivalves, reaching the highest concentrations (plateau) after 1 h in mussels and 2 h in oysters. Under the same concentrations of E. coli in seawater, a significantly higher plateau was reached in mussels than oysters. Significant correlations between the E. coli concentration in seawater and bivalves (CR; concentration ratio) were found. The results clearly showed that CR was controlled by temperature and salinity of seawater. Changes in temperature had a strong effect on CR fluctuation, whereas in oysters an effect of changes in salinity on CR variation was also found only in oysters. The interaction between temperature and salinity was statistically significant and suggested that their simultaneous effects on CR were significantly greater than when each of these factors acted independently. The highest E. coli concentrations in mussels and oysters exceeded the concentrations in seawater by an order of magnitude at least, while the CR in mussels exceeded the CR in oysters by 7.7- to 38.5-fold.U ovom radu istraživan je zajednički utjecaj temperature i saliniteta morske vode na akumuliranje bakterije Escherichia coli u dagnji (Mytilus galloprovincialis) i kamenici (Ostrea edulis) u eksperimentalnim uvjetima pri različitim koncentracijama E. coli u morskoj vodi. Eksperimenti su provođeni u bazenima volumena 3000 L, u prirodnim rasponima temperatura (12oC, 18oC i 24oC) i saliniteta (32 psu i 37 psu), karakterističnim za priobalje Jadranskog mora. U istraživanom rasponu koncentracija E. coli u morskoj vodi (4x10-4.6x103 EC/100 ml), zabilježena je brza akumulacija bakterija u školjkašima, a najviše koncentracije (prag) dosezane su u prvom satu kod dagnje i drugom satu kod kamenice. pri jednakim koncentracijama E. coli u morskoj vodi više maksimalne koncentracije E. coli zabilježene su kod dagnje. Utvrđena je jasna pozitivna povezanost između koncentracije E. coli u ambijentalnoj vodi i njene koncentracije u školjkašima (CR;concentration ratio-omjer koncentracija). Utvrđeno je također da je CR kontroliran temperaturom i salinitetom morske vode. Kod dagnje su promjene temperature značajno utjecale na promjene CR, dok su kod kamenice, osim temperature, na promjene CR značajno utjecale i promjene saliniteta. I kod dagnje i kod kamenice, zajednički učinak temperature i saliniteta bio je značajniji od njihovog pojedinačnog učinka. Najviše koncentracije E. coli u školjkašima za najmanje jedan red veličine su premašivale koncentracije u moru, dok je omjer najviših koncentracija u dagnjama i kamenicama bio u rasponu 7.7- 38.5

A Combined 90/900 MHz IC Architecture for Smart Tag Application

In this work we present a combined 90/900 MHz Energy Harvesting Architecture for active smart tag Application. The harvester takes advantages from a dedicated diplexer and a power manager for battery life enhancement purposes. The system has been optimized in the 900 MHz frequency range by analyzing a probabilistic approach used for modeling the possible amount of Global System for Mobile communication (GSM) energy that could be harvested while a fixed power downlink scenario has been adopted for the 90MHz band. A preliminary IC system with a 0.18μm CMOS SMIC technology has been designed and optimized at 90 and 900 MHz while discrete element board, to be integrated with the proposed IC, with commercial components has been developed and tested. Concerning simulation results on the IC design they have confirmed that the integrated system handles an incoming power typically ranging from -25 dBm to 5 dBm by rectifying the variable input signals into a DC voltage source with an average 50% efficiency

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