Fresh Pasta Production Enriched with Spirulina platensis Biomass

The aim of this work was to study the enrichment of Spirulina platensis in wheat flour to prepare fresh pasta to evaluate the green color and nutritional enrichment in addition to functional properties due to the presence of the bioactive compounds in the cyanobacterium. The pastas were evaluated for the centesimal composition, microbiological contamination, sensorial acceptance and technological characteristics such as cooking time, water absorption, volume displacement and loss of solids. The superior protein contents and the satisfactory technological and sensorial attributes compared with the control with no cyanobacterium showed the usefulness of incorporating S. platensis biomass in the fresh pastas. The microbiological quality was in compliance with the legislation in force. The sensorial quality was considered satisfactory ("liked very much") and purchase intention high ("probably would buy").

Bioaccumulation Of Microcystins In Lettuce

The contamination of lettuce (Lactuca sativa L.) by water-borne crude extracts of the cyanobacterium microcystin-producing Microcystis aeruginosa (Kutzing) Kutzing was investigated. The aim of the study was to determine whether bioaccumulation of microcystins occurs in lettuce foliar tissue when sprayed with solutions containing microcystins at concentrations observed in aquatic systems (0.62 to 12.5 mu g center dot L-1). Microcystins were found in lettuce foliar tissues (8.31 to 177.8 mu g per Kg of fresh weight) at all concentrations of crude extracts. Spraying with water containing microcystins and cyanobacteria may contaminate lettuce at levels higher than the daily intake of microcystins recommended by the World Health Organization (WHO), underscoring the need to monitor such food exposure pathways by public authorities.

Fresh pasta production enriched with Spirulina platensis biomass

The aim of this work was to study the enrichment of Spirulina platensis in wheat flour to prepare fresh pasta to evaluate the green color and nutritional enrichment in addition to functional properties due to the presence of the bioactive compounds in the cyanobacterium. The pastas were evaluated for the centesimal composition, microbiological contamination, sensorial acceptance and technological characteristics such as cooking time, water absorption, volume displacement and loss of solids. The superior protein contents and the satisfactory technological and sensorial attributes compared with the control with no cyanobacterium showed the usefulness of incorporating S. platensis biomass in the fresh pastas. The microbiological quality was in compliance with the legislation in force. The sensorial quality was considered satisfactory ( liked very much ) and purchase intention high ( probably would buy ).

Hsp70-Chaperone und ihre Rolle bei der Thylakoidmembranbiogenese im Cyanobakterium Synechocystis sp. PCC 6803

Im Genom des Cyanobakteriums Synechocystis sp. PCC6803 sind vier homologe Hsp70-Proteine kodiert. Im Rahmen dieser Arbeit konnten neue Erkenntnisse über die möglichen Funktionen der einzelnen Mitglieder der Hsp70-Proteinfamilie in dem Modellorganismus gewonnen bzw. bekannte Aufgabenbereiche erweitert werden. Wie für E. coli schon gezeigt, konnte auch für Synechocystis sp. nachgewiesen werden, dass eine Deletion des ribosomassoziierten Chaperons Trigger Factor ohne Beeinträchtigung der Zellviabilität möglich ist. Darüber hinaus war auch eine Doppeldeletion mit dnaK1 durchführbar. Als Auswirkung der Deletion ließ sich in den jeweiligen Deletionsstämmen eine veränderte Expression der homologen Hsp70-Proteine und Trigger Factor nachweisen. Mit Hilfe der Synechocystis sp.-Mutationsstämme ∆dnaK1, ∆dnaK2, ∆dnaK3, ∆tig und ∆dnaK1∆tig wurden Auswirkungen der Deletion bzw. Depletion umfassend dargestellt und daraus hervorgehende putative Funktionen eingehend diskutiert. Die Reduzierung der zellulären DnaK3-Konzentration um etwa 70 % führte im Depletionsstamm ΔdnaK3 zu weitreichenden physiologischen Änderungen hinsichtlich photosynthetischer Prozesse. Zusammen mit einer lichtabhängigen Expression, konnte DnaK3 als essentieller Faktor für die funktionelle Aufrechterhaltung der Thylakoidmembran identifiziert werden. Durch die Analyse des Proteoms und Lipidoms dunkeladaptierter Synechocystis sp.-Zellen konnte im Vergleich zu älteren Studien eine erheblich größere Anzahl von Proteinen detektiert und quantifiziert werden, womit neue Erkenntnisse über die physiologischen Veränderungen unter heterotrophem Wachstum sowie der Thylakoidmembranbiogenese gewonnen werden konnten.

Biotic and abiotic parameters and cynobacteria abundance during an experimental set-up with varying pCO2 conditions

Heterocystous cyanobacteria of the genus Nodularia form extensive blooms in the Baltic Sea and contribute substantially to the total annual primary production. Moreover, they dispense a large fraction of new nitrogen to the ecosystem when inorganic nitrogen concentration in summer is low. Thus, it is of ecological importance to know how Nodularia will react to future environmental changes, in particular to increasing carbon dioxide (CO2) concentrations and what consequences there might arise for cycling of organic matter in the Baltic Sea. Here, we determined carbon (C) and dinitrogen (N2) fixation rates, growth, elemental stoichiometry of particulate organic matter and nitrogen turnover in batch cultures of the heterocystous cyanobacterium Nodularia spumigena under low (median 315 µatm), mid (median 353 µatm), and high (median 548 µatm) CO2 concentrations. Our results demonstrate an overall stimulating effect of rising pCO2 on C and N2 fixation, as well as on cell growth. An increase in pCO2 during incubation days 0 to 9 resulted in an elevation in growth rate by 84 ± 38% (low vs. high pCO2) and 40 ± 25% (mid vs. high pCO2), as well as in N2 fixation by 93 ± 35% and 38 ± 1%, respectively. C uptake rates showed high standard deviations within treatments and in between sampling days. Nevertheless, C fixation in the high pCO2 treatment was elevated compared to the other two treatments by 97% (high vs. low) and 44% (high vs. mid) at day 0 and day 3, but this effect diminished afterwards. Additionally, elevation in carbon to nitrogen and nitrogen to phosphorus ratios of the particulate biomass formed (POC : POP and PON : POP) was observed at high pCO2. Our findings suggest that rising pCO2 stimulates the growth of heterocystous diazotrophic cyanobacteria, in a similar way as reported for the non-heterocystous diazotroph Trichodesmium. Implications for biogeochemical cycling and food web dynamics, as well as ecological and socio-economical aspects in the Baltic Sea are discussed.

Effects of ultraviolet radiation and CO2 increase on winter phytoplankton assemblages in a temperate coastal lagoon

Increases in ultraviolet radiation (UVR) and CO2 affect phytoplankton growth and mortality in a variety of different ways. However, in situ responses of natural phytoplankton communities to climate change, as well as its effects on phytoplankton annual cycles, are still largely unknown. Although temperature and UVR have been increasing in temperate latitudes during winter, this season is still particularly neglected in climate change studies, being considered a non-active season regarding phytoplankton growth and production. Additionally, coastal lagoons are highly productive ecosystems and very vulnerable to climate change. This study aims, therefore, to evaluate the short-term effects of increased UVR and CO2 on the composition and growth of winter phytoplankton assemblages in a temperate coastal lagoon. During winter 2012, microcosm experiments were used to evaluate the isolated and combined effects of UVR and CO2, under ambient and high CO2 treatments, exposed to ambient UV levels and photosynthetically active radiation (PAR), or to PAR only. Phytoplankton composition, abundance, biomass and photosynthetic parameters were evaluated during the experiments. Significant changes were observed in the growth of specific phytoplankton groups, leading to changes in community composition. The cyanobacterium Synechococcus was dominant at the beginning of the experiment, but it was negatively affected by UVR and CO2. Diatoms clearly benefited from high CO2 and UVR, particularly Thalassiosira. Despite the changes observed in specific phytoplankton groups, growth and production of the whole phytoplankton community did not show significant responses to UVR and/or CO2.

Trichodesmium's strategies to alleviate phosphorus limitation in the future acidified oceans

Global warming may exacerbate inorganic nutrient limitation, including phosphorus (P), in the surface-waters of tropical oceans that are home to extensive blooms of the marine diazotrophic cyanobacterium, Trichodesmium. We examined the combined effects of P limitation and pCO2, forecast under ocean acidification scenarios, on Trichodesmium erythraeum IMS101 cultures. We measured nitrogen acquisition, glutamine synthetase activity, C uptake rates, intracellular Adenosine Triphosphate (ATP) concentration and the pool sizes of related key proteins. Here, we present data supporting the idea that cellular energy re-allocation enables the higher growth and N2 fixation rates detected in Trichodesmium cultured under high pCO2. This is reflected in altered protein abundance and metabolic pools. Also modified are particulate organic carbon and nitrogen production rates, enzymatic activities, and cellular ATP concentrations. We suggest that adjusting these cellular pathways to changing environmental conditions enables Trichodesmium to compensate for low P availability and to thrive in acidified oceans. Moreover, elevated pCO2 could provide Trichodesmium with a competitive dominance that would extend its niche, particularly in P-limited regions of the tropical and subtropical oceans.

Response of Nodularia spumigena to pCO2 - Part 3: Turnover of phosphorus compounds

Diazotrophic cyanobacteria often form extensive summer blooms in the Baltic Sea driving their environment into phosphate limitation. One of the main species is the heterocystous cyanobacterium Nodularia spumigena. N. spumigena exhibits accelerated uptake of phosphate through the release of the exoenzyme alkaline phosphatase that also serves as an indicator of the hydrolysis of dissolved organic phosphorus (DOP). The present study investigated the utilization of DOP and its compounds (e.g. ATP) by N. spumigena during growth under varying CO2 concentrations, in order to estimate potential consequences of ocean acidification on the cell's supply with phosphorus. Cell growth, phosphorus pool fractions, and four DOP-compounds (ATP, DNA, RNA, and phospholipids) were determined in three set-ups with different CO2 concentrations (341, 399, and 508 µatm) during a 15-day batch experiment. The results showed rapid depletion of dissolved inorganic phosphorus (DIP) in all pCO2 treatments while DOP utilization increased with elevated pCO2, in parallel with the growth stimulation of N. spumigena. During the growth phase, DOP uptake was enhanced by a factor of 1.32 at 399 µatm and of 2.25 at 508 µatm compared to the lowest pCO2 concentration. Among the measured DOP compounds, none was found to accumulate preferentially during the incubation or in response to a specific pCO2 treatment. However, at the beginning 61.9 ± 4.3% of the DOP were not characterized but comprised the most highly utilized fraction. This is demonstrated by the decrement of this fraction to 27.4 ± 9.9% of total DOP during the growth phase, especially in response to the medium and high pCO2 treatment. Our results indicate a stimulated growth of diazotrophic cyanobacteria at increasing CO2 concentrations that is accompanied by increasing utilization of DOP as an alternative P source.

Colimitation of the unicellular photosynthetic diazotroph Crocosphaera watsonii by phosphorus, light, and carbon dioxide

We describe interactive effects of total phosphorus (total P = 0.1-4.0 µmol/L; added as H2NaPO4), irradiance (40 and 150 µmol quanta/m**2/s), and the partial pressure of carbon dioxide (P-CO2; 19 and 81 Pa, i.e., 190 and 800 ppm) on growth and CO2- and dinitrogen (N-2)-fixation rates of the unicellular N-2-fixing cyanobacterium Crocosphaera watsonii (WH0003) isolated from the Pacific Ocean near Hawaii. In semicontinuous cultures of C. watsonii, elevated P-CO2 positively affected growth and CO2- and N-2-fixation rates under high light. Under low light, elevated P-CO2 positively affected growth rates at all concentrations of P, but CO2- and N-2-fixation rates were affected by elevated P-CO2 only when P was low. In both high-light and low-light cultures, the total P requirements for growth and CO2- and N-2-fixation declined as P-CO2 increased. The minimum concentration (C-min) of total P and half-saturation constant (K-1/2) for growth and CO2- and N-2-fixation rates with respect to total P were reduced by 0.05 µmol/L as a function of elevated P-CO2. We speculate that low P requirements under high P-CO2 resulted from a lower energy demand associated with carbon-concentrating mechanisms in comparison with low-P-CO2 cultures. There was also a 0.10 µmol/L increase in C-min and K-1/2 for growth and N-2 fixation with respect to total P as a function of increasing light regardless of P-CO2 concentration. We speculate that cellular P concentrations are responsible for this shift through biodilution of cellular P and possibly cellular P uptake systems as a function of increasing light. Changing concentrations of P, CO2, and light have both positive and negative interactive effects on growth and CO2-, and N-2-fixation rates of unicellular oxygenic diazotrophs like C. watsonii.