Folaatin, niasiinin, B2- ja B12-vitamiinin pitoisuus kaupallisissa mikrolevävalmisteissa ja laboratorio-olosuhteissa kasvatetuissa mikrolevissä

Mikrolevät ovat lupaavia elintarvike- ja bioteknologian sovellusten raaka-aineita niiden sisältämien ravintoaineiden vuoksi. Mikrolevien B-vitamiineista on olemassa vain vähän tutkimustietoa, joista osa perustuu osittain epätarkkoihin määritysmenetelmiin. Tutkielman kirjallisuusosio käsitteli mikroleviä, niiden analytiikkaa ja vitamiinitaloutta sekä tutkielmassa määritettyjen B-vitamiinien, folaatin, niasiinin, B2- ja B12-vitamiinin rakenteellisia ominaisuuksia, esiintymistä elintarvikkeissa ja analytiikkaa. Tutkielman kokeellisen osion tavoitteena oli tutkia kaupallisia mikrolevävalmisteita (Chlorella sp. ja Arthrospira sp. (spirulina)) ja laboratoriossa kasvatettuja mikroleviä (Euglena gracilis) folaatin, niasiinin, B2- ja B12-vitamiinin lähteenä. B12-, B2-vitamiinin ja niasiinin kokonaispitoisuudet määritettiin jokaiselle vitamiinille erikseen validoidulla nestekromatografisella UHPLC-menetelmällä. Kokonaisfolaattipitoisuus määritettiin mikrobiologisesti ja folaatin eri vitameerit UHPLC-menetelmällä. B12-vitamiinipitoisuus määritettiin UHPLC-menetelmällä ja mikrobiologisesti. Näytteiden B12-vitamiinin ihmiselle aktiivinen muoto varmistettiin massaspektrometrisesti. Niasiinin määritysmenetelmässä käytettiin happohydrolyysiä emäshydrolyysin sijaan. Chlorella-valmisteiden kokonaisfolaattipitoisuudet olivat suuria, mutta E. gracilis -näytteiden mikrobiologisesti määritetyt folaattipitoisuudet olivat jopa 3 kertaa suurempia kuin chlorella-valmisteiden. Spirulina-näytteiden B12-vitamiinipitoisuus oli mikrobiologisesti määritettynä selkeästi suurempi kuin UHPLC-laitteistolla määritetty, mikä johtui mikrobiologisen menetelmän antamasta positiivisesta vasteesta myös vitamiinin ei-aktiiviselle pseudomuodolle. Kaupalliset mikrolevävalmisteet sisälsivät vähemmän B2-vitamiinia kuin E. gracilis -näytteet. Chlorella- ja E. gracilis -näytteiden niasiinipitoisuudet olivat suurempia kuin spirulina-valmisteiden. Kaupalliset mikrolevävalmisteet sisälsivät tutkielman mukaan vaihtelevasti tutkittuja B-vitamiineja. Chlorella-valmisteet olivat erinomaisia folaatin, B12-vitamiinin ja niasiinin lähteitä. Spirulina-valmisteiden B12-pitoisuudesta valtaosa koostui vitamiinin pseudomuodosta – silti spirulina-valmisteiden voitiin todeta olevan kohtuullisen hyviä B12-vitamiinin lähteitä. Laboratoriossa kasvatettu E. gracilis osoittautui keskimääräistä paremmaksi tutkittujen B-vitamiinien lähteeksi kuin chlorella- tai spirulina-valmisteet, mutta sitä ei ole hyväksytty elintarvikekäyttöön – ainakaan vielä.Microalgae are promising raw materials for food- and biotechnology because they contain a lot of proteins, unsaturated fatty acids, pigments, vitamins and minerals. There are few studies on vitamin B in microalgae and some of them are based on partly inaccurate methods. Microalgae in general, analytical methods regarding their analysis and how they use vitamins were discussed in the literature part of this thesis. The structures, chemical properties and occurrence in foods as well as commonly used analytical methods of the vitamins in question were presented. The aim of the experimental part of this thesis was to analyse commercially marketed microalgae supplements (Chlorella sp. and Arthrospira sp. (spirulina)) and laboratory-grown microalga (Euglena gracilis) as potential sources of folate, niacin, vitamin B2 and B12. Contents of vitamin B12, B2 and niacin were analysed using UHPLC method separately validated for each vitamin. The total folate content was analysed microbiologically and folate vitamers by using UHPLC. The vitamin B12 was analysed microbiologically and the active forms of vitamin B12 were confirmed using LC-MS. Acid hydrolysis was used in analysing niacin content. The total folate content in chlorella supplements was of the same order when analysed microbiologically or with UHPLC. Instead, in spirulina supplements the microbiologically analysed total folate content was higher than the total folate content based on the sum of folate vitamers analysed with UHPLC. At most, the total folate content of E. gracilis -sample was 3-fold higher than in commercial microalgae supplements. Especially in spirulina supplements, the vitamin B12 contents were clearly higher when analysed microbiologically than they were when analysed with UHPLC. The difference was most likely due to pseudocobalamin that resembled vitamin B12. On average E. gracilis -samples had higher vitamin B2 content than the commercial supplements. E. gracilis -samples and chlorella supplements contained more niacin than spirulina supplements. According to this thesis, commercially marketed microalgae supplements contained different amounts of vitamin B. Chlorella sp. was proved to be a great source of folate, vitamin B12 and niacin and moderate source of B2. The majority of vitamin B12 in Arthrospira sp. (spirulina) was pseudocobalamin. Despite that, spirulina supplements proved to be a moderate source of vitamin B12. On average, E. gracilis had the highest vitamin B content and it would potentially be an excellent source of vitamin B – if it was accepted for food use

Most Common Mistakes and Risks in Winter Concreting

Talvibetonointi on alle 5 °C:n lämpötilassa toteutettavaa betonointia, jonka ongelmat aiheutuvat suurimmaksi osaksi kylmästä lämpötilasta. Betonin lujuudenkehitys hidastuu lämpötilan laskiessa, joka voi johtaa talvella siihen, etteivät muotinpurkulujuudet täyty suunnitellussa aikataulussa. Jotta betonin laatu ei olisi riippuvainen vallitsevasta vuodenajasta, sääolosuhteet tulee huomioida betonointiprosessin jokaisessa vaiheessa. Betonointiprosessin monimutkaistuessa talvella riskit lisääntyvät ja prosessivaiheiden aikana tehtävien virheiden todennäköisyys kasvaa. Tässä työssä on tutkittu talvibetonointiprosessissa esiintyviä yleisiä riskejä ja virheitä prosessivaiheittain rakennusalan julkaisujen ja kirjallisuuden pohjalta. Lisäksi huomioidaan betonin jäätymisen ja halkeilun aiheuttamat ongelmat sekä tarkastellaan betonin lujuudenkehitykselle alhaisesta lämpötilasta syntyviä riskejä. Prosessivaiheiden ohella työssä paneudutaan betonointityön työturvallisuus-, talous- ja aikatauluriskeihin. Työn tarkoituksena on koota talvibetonoinnin yleisimmistä riskeistä ja virheistä kattava kokonaisuus rakennusalan julkaisujen pohjalta. Työ on toteutettu kirjallisuustutkielmana ja aineistona on käytetty pääasiassa rakennusalan kirjallisuutta ja internetjulkaisuja. Työn tutkimustuloksena havaitaan, että talvella betonoitaessa suurin riskitekijä on alhainen lämpötila. Talvella alhaisessa lämpötilassa valettu lämmittämätön betoni on altis lujuuden alenemalle, jäätymiselle, hidastuneelle lujuudenkehitykselle sekä muodonmuutoksille. Betonoinnissa tehtävät virheet johtavat usein betonin halkeiluun, joka heikentää betonirakenteen toimintaa. Työssä havaitaan betonointiprosessin oikeanlaisen toteutuksen tärkeys, sillä väärin toteutettu betonointi voi johtaa kustannus-, aikataulu- ja työturvallisuusongelmiin. Työ on rajattu koskemaan Suomessa talonrakennustyömailla tapahtuvaa talvibetonointia, joten tarkempia tuloksia haluttaessa tutkimus tulisi ulottaa myös muihin betonointityömaatyyppeihin tai erilaiseen talvi-ilmastoon. Kattavamman tutkimustuloksen saavuttaisi myös huomioimalla betonin suhteuttamisvaiheessa tai betonitehtaalla tapahtuvat yleiset riskit ja virheet, joita tässä työssä ei ole tarkasteltu

Autochthonous organic matter promotes DNRA and suppresses N2O production in sediments of the coastal Baltic Sea

Coastal environments are nitrogen (N) removal hot spots, which regulate the amount of land-derived N reaching the open sea. However, mixing between freshwater and seawater creates gradients of inorganic N and bioavailable organic matter, which affect N cycling. In this study, we compare nitrate reduction processes between estuary and offshore archipelago environments in the coastal Baltic Sea. Denitrification rates were similar in both environments, despite lower nitrate and carbon concentrations in the offshore archipelago. However, DNRA (dissimilatory nitrate reduction to ammonium) rates were higher at the offshore archipelago stations, with a higher proportion of autochthonous carbon. The production rate and concentrations of the greenhouse gas nitrous oxide (N2O) were higher in the estuary, where nitrate concentrations and allochthonous carbon inputs are higher. These results indicate that the ratio between nitrate and autochthonous organic carbon governs the balance between N-removing denitrification and N-recycling DNRA, as well as the end-product of denitrification. As a result, a significant amount of the N removed in the estuary is released as N2O, while the offshore archipelago areas are characterized by efficient internal recycling of N. Our results challenge the current understanding of the role of these regions as filters of land-to-sea transfer of N.Peer reviewe

Hurricane Disturbance Stimulated Nitrification and Altered Ammonia Oxidizer Community Structure in Lake Okeechobee and St. Lucie Estuary (Florida)

© Copyright © 2020 Hampel, McCarthy, Aalto and Newell. Nitrification is an important biological link between oxidized and reduced forms of nitrogen (N). The efficiency of nitrification plays a key role in mitigating excess N in eutrophic systems, including those with cyanobacterial harmful algal blooms (cyanoHABs), since it can be closely coupled with denitrification and removal of excess N. Recent work suggests that competition for ammonium (NH4+) between ammonia oxidizers and cyanoHABs can help determine microbial community structure. Nitrification rates and ammonia-oxidizing archaeal (AOA) and bacterial (AOB) community composition and gene abundances were quantified in Lake Okeechobee and St. Lucie Estuary in southern Florida (United States). We sampled during cyanobacterial (Microcystis) blooms in July 2016 and August 2017 (2 weeks before Hurricane Irma) and 10 days after Hurricane Irma made landfall. Nitrification rates were low during cyanobacterial blooms in Lake Okeechobee and St. Lucie Estuary, while low bloom conditions in St. Lucie Estuary coincided with greater nitrification rates. Nitrification rates in the lake were correlated (R2 = 0.94; p = 0.006) with AOA amoA abundance. Following the hurricane, nitrification rates increased by an order of magnitude, suggesting that nitrifiers outcompeted cyanobacteria for NH4+ under turbid, poor light conditions. After Irma, AOA and AOB abundances increased in St. Lucie Estuary, while only AOB increased in Lake Okeechobee. AOA sequences clustered into three major lineages: Nitrosopumilales (NP), Nitrososphaerales (NS), and Nitrosotaleales (NT). Many of the lake OTUs placed within the uncultured and uncharacterized NS δ and NT β clades, suggesting that these taxa are ecologically important along this eutrophic, lacustrine to estuarine continuum. After the hurricane, the AOA community shifted toward dominance by freshwater clades in St. Lucie Estuary and terrestrial genera in Lake Okeechobee, likely due to high rainfall and subsequent increased turbidity and freshwater loading from the lake into the estuary. AOB community structure was not affected by the disturbance. AOA communities were consistently more diverse than AOB, despite fewer sequences recovered, including new, unclassified, eutrophic ecotypes, suggesting a wider ecological biogeography than the oligotrophic niche originally posited. These results and other recent reports contradict the early hypothesis that AOB dominate ammonia oxidation in high-nutrient or terrestrial-influenced systems

Eutrophication reduces the nutritional value of phytoplankton in boreal lakes

Eutrophication (as an increase in total phosphorus [TP]) increases harmful algal blooms and reduces the proportion of high-quality phytoplankton in seston and the content of ω-3 long-chain polyunsaturated fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) in fish. However, it is not well-known how eutrophication affects the overall nutritional value of phytoplankton. Therefore, we studied the impact of eutrophication on the production (as concentration; μg L−1) and content (μg mg C−1) of amino acids, EPA, DHA, and sterols, i.e., the nutritional value of phytoplankton in 107 boreal lakes. The lakes were categorized in seven TP concentration categories ranging from ultra-oligotrophic (50 μg L−1). Phytoplankton total biomass increased with TP as expected, but in contrast to previous studies, the contribution of high-quality phytoplankton did not decrease with TP. However, the high variation reflected instability in the phytoplankton community structure in eutrophic lakes. We found that the concentration of amino acids increased in the epilimnion whereas the concentration of sterols decreased with increasing TP. In terms of phytoplankton nutritional value, amino acids, EPA, DHA, and sterols showed a significant quadratic relationship with the lake trophic status. More specifically, the amino acid contents were the same in the oligo- and mesotrophic lakes, but substantially lower in the eutrophic lakes (TP > 35 μg L−1/1.13 μmol L−1). The highest EPA and DHA content in phytoplankton was found in the mesotrophic lakes, whereas the sterol content was highest in the oligotrophic lakes. Based on these results, the nutritional value of phytoplankton reduces with eutrophication, although the contribution of high-quality algae does not decrease. Therefore, the results emphasize that eutrophication, as excess TP, reduces the nutritional value of phytoplankton, which may have a significant impact on the nutritional value of zooplankton, fish, and other aquatic animals at higher food web levels.peerReviewe

Mitigating agricultural nitrogen load with constructed ponds in northern latitudes : A field study on sedimental denitrification rates

Constructed agricultural ponds and wetlands can reduce nitrogen loading from agriculture especially in areas where warm climate predominates. However, in cold climate temperature-dependency of microbiological processes have raised the question about the applicability of constructed wetlands in N removal. We measured in situ denitrification rates in a constructed agricultural pond using N-15-isotope pairing technique at ambient light and temperature throughout a year as well as diurnally. The field IPT measurements were combined with a wide set of potentially important explanatory data, including air temperature, photosynthetically active radiation, precipitation, discharge, nitrate plus other water quality variables, sediment temperature, oxygen concentration and penetration depth, diffusive oxygen uptake and sediment organic carbon. Denitrification varied, on average, diurnally between 12 and 314 mu mol N m(-2) h(-1) and seasonally between 0 and 12409 mu mol m(-2) h(-1). Light and oxygen regulated the diel variation of denitrification, but seasonally denitrification was governed by a combination of temperature, oxygen and turbidity. The results indicated that the real N removal rate might be 30-35% higher than the measured daytime rates, suggesting that neglecting the diel variation of denitrification we may underestimate N removal capacity of shallow sediments. We conclude, that by following recommended wetland:catchment - size ratios, boreal agricultural ponds can efficiently remove nitrogen by denitrification in summer and in autumn, while in winter and in spring the contribution of denitrification might be negligible relative to the loading, especially with short residence time.Peer reviewe

Denitrifying microbial communities along a boreal stream with varying land-use

Streams have an important role in regulating nitrogen (N) transportation from terrestrial ecosystems to downstream waters. Here, we examined how catchment land-use affects potential denitrification rates and the function and composition of denitrifier communities in boreal stream sediments, using stable isotope incubations and qPCR and 454-pyrosequencing targeted on nirS, nirK and nosZ genes. Although land-use influenced the water chemistry as higher nitrite+nitrate (NOx)-concentration at the agriculture-affected sampling point, sediment organic matter content was found to be the key factor in regulating potential denitrification rates. However, the abundance as well as the diversity and community composition of denitrifying microbes, and genetic N2O production potential (the ratio between nirS+nirK and nosZ gene abundances) were connected to both NOx- and sediment quality. Overall, our results suggest that catchment land-use-driven changes in N and carbon availability affect the denitrification rates, and possibly N-2:N2O production ratio, in boreal streams, through altering denitrifier abundance and community composition.Peer reviewe

Organic matter lability modifies the vertical structure of methane-related microbial communities in lake sediments

Eutrophication increases the input of labile, algae-derived, organic matter (OM) into lake sediments. This potentially increases methane (CH4) emissions from sediment to water through increased methane production rates and decreased methane oxidation efficiencyefficiency in sediments. However, the effecteffect of OM lability on the structure of methane oxidizing (methanotrophic) and methane producing (methanogenic) microbial communities in lake sediments is still understudied. We studied the vertical profilesprofiles of the sediment and porewater geochemistry and the microbial communities (16S rRNA gene amplicon sequencing) at fivefive profundal stations of an oligo-mesotrophic, boreal lake (Lake Paajarvi, Finland), varying in surface sediment OM sources (assessed via sediment C:N ratio). Porewater profilesprofiles of methane, dissolved inorganic carbon (DIC), acetate, iron, and sulfur suggested that sites with more autochthonous OM showed higher overall OM lability, which increased remineralization rates, leading to increased electron acceptor (EA) consumption and methane emissions from sediment to water. When OM lability increased, the abundance of anaerobic nitrite-reducing methanotrophs (Candidatus Methylomirabilis) relative to aerobic methanotrophs (Methylococcales) in the methane oxidation layer of sediment surface decreased, suggesting that Methylococcales were more competitive than Ca. Methylomirabilis under decreasing redox conditions and increasing methane availability due to their more diverse metabolism (fermentation and anaerobic respiration) and lower affinityaffinity for methane. Furthermore, when OM lability increased, the abundance of methanotrophic community in the sediment surface layer, especially Ca. Methylomirabilis, relative to the methanogenic community decreased. We conclude that increasing input of labile OM, subsequently affectingaffecting the redox zonation of sediments, significantlysignificantly modifies the methane producing and consuming microbial community of lake sediments

The role of organic matter and microbial community controlling nitrate reduction under elevated ferrous iron concentrations in boreal lake sediments

The nitrogen availability, that affects the greenhouse gas emission and the trophic level of lakes, is controlled mainly by microbial processes. We measured in a boreal nitrate and iron rich lake how the rates of potential denitrification and dissimilatory nitrate reduction to ammonia (DNRA) are affected by degradability of organic matter and availability of aqueous ferrous iron. We also investigated the microbial community by using 16S rRNA gene and shotgun metagenomic sequencing approach, which allows taxonomic analyses and detection of metagenome-assembled genomes (MAGs) containing genes for both nitrate reduction and iron oxidation. The results show that truncated denitrification, leading to release of nitrous oxide, is favored over dinitrogen production in conditions where the degradability of the organic matter is low. DNRA rates were always minor compared to denitrification and appeared to be independent of the degradability of organic carbon. Reduced iron stimulated nitrate reducing processes, although consistently only DNRA. However, the proportion of MAGs containing DNRA genes was low suggesting chemistry driven stimulation by reduced iron. Nevertheless, the metagenomic analyses revealed unique taxa genetically capable of oxidizing iron and reducing nitrate simultaneously. Overall, the results highlight the spatial variability in microbial community and nitrous oxide emissions in boreal lake sediments.Peer reviewe

Riboflavin, niacin, folate and vitamin B12 in commercial microalgae powders

This study aimed to investigate the riboflavin, niacin, folate and B12 content in microalgae powders. Riboflavin was determined with an ultra-high-performance liquid chromatographic (UHPLC) method after extraction and a two-enzyme treatment. Niacin analysis involved mild acidic hydrolysis, with niacin quantitated as the sum of nicotinic acid and nicotinamide using a UHPLC method. Both a microbiological (MBA) and a UHPLC method was used for vitamin B12 quantification as a cyanocobalamin (CNCb1) and UHPLC-mass spectrometry was used to confirm the vitamin B12 form. Total folate was determined both with MBA and as a sum of the vitamers with a UHPLC method after extraction and tri-enzyme treatment. The riboflavin and niacin content varied from 21 to 41 mu g/g and 0.13-0.28 mg/g, respectively, in Chlorella sp., Spirulina (Arthrospira sp.) and Nannochloropsis gaditana powders. Chlorella powders were, on average, richer in total folate (19.7 mu g/g) than Spirulina powders were (3.5 mu g/g). The sum of the folate vitamers determined with UHPLC matched better with the microbiological total folate content in Chlorella than in Spirulina powders. Pseudovitamin B12 was the predominant form over active vitamin B12 in Spirulina powders, whereas Chlorella sp. and N. gaditana powders solely contained active vitamin B12 up to 2.1 mu g/g.Peer reviewe