Doubling of Microalgae Productivity by Oxygen Balanced Mixotrophy

Microalgae productivity was doubled by designing an innovative mixotrophic cultivation strategy that does not require gas-liquid transfer of oxygen or carbon dioxide. Chlorella sorokiniana SAG 211/8K was cultivated under continuous operation in a 2 L stirred-tank photobioreactor redesigned so that respiratory oxygen consumption was controlled by tuning the acetic acid supply. In this mixotrophic setup, the reactor was first operated with aeration and no net oxygen production was measured at a fixed acetic acid supply rate. Then, the aeration was stopped and the acetic acid supply rate was automatically regulated to maintain a constant dissolved oxygen level using process control software. Respiratory oxygen consumption was balanced by phototrophic oxygen production, and the reactor was operated without any gas-liquid exchange. The carbon dioxide required for photosynthesis was completely provided by the aerobic conversion of acetic acid. Under this condition, the biomass/substrate yield was 0.94 C-molx·C-molS -1. Under chemostat conditions, both reactor productivity and algal biomass concentration were doubled in comparison to a photoautotrophic reference culture. Mixotrophic cultivation did not affect the photosystem II maximum quantum yield (Fv/Fm) and the average-dry-weight-specific optical cross section of the microalgal cells. Only light absorption by chlorophylls over carotenoids decreased by 9% in the mixotrophic culture in comparison to the photoautotrophic reference. Our results demonstrate that photoautotrophic and chemoorganotrophic metabolism operate concurrently and that the overall yield is the sum of the two metabolic modes. At the expense of supplying an organic carbon source, photobioreactor productivity can be doubled while avoiding energy intensive aeration.</p

Oxygen Balanced Mixotrophy under Day-Night Cycles

Using sunlight to fuel photosynthesis exposes microalgae to day–night cycles. Under day–night cycles microalgae tend to synchronize their metabolism by optimizing light utilization during daytime. During night storage compounds are consumed, leading to biomass losses and demand of O2. We investigated “oxygen balanced” mixotrophy under 14:10 day/night cycles. In this mixotrophic setup, photosynthetic O2 production was balanced by respiratory oxygen consumption and CO2 required for photosynthesis was provided by aerobic conversion of acetic acid. This strategy allowed operation of the reactor without any gas–liquid exchange during daytime. Under these conditions Chlorella sorokiniana SAG 211/8K converted 96% of the substrate into biomass. Mixotrophic cultivation did not affect the photosystem II maximum quantum yield (Fv/Fm) or pigment contents of the microalgal cells. Mixotrophic biomass contained 50% w/w of protein and 7.3 mg g–1 of lutein. Acetic acid feeding was discontinued at night and aeration initiated. Respiration was monitored by online off-gas analysis and O2 consumption and CO2 production rates were determined. Biomass night losses were around 7% on carbon basis with no significant difference between mixotrophic and photoautotrophic cultures. Over 24 h, the mixotrophic culture required 61 times less gaseous substrate and its biomass productivity was doubled compared to the photoautotrophic counterpart.publishedVersionPaid Open Acces

Mixotrophic cultivation of Galdieria sulphuraria for C-phycocyanin and protein production

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MAB2.0 project: Integrating algae production into wastewater treatment

Different species of microalgae are highly efficient in removing nutrients from wastewater streams and are able to grow using flue gas as a CO2 source. These features indicate that application of microalgae has a promising outlook in wastewater treatment. However, practical aspects and process of integration of algae cultivation into an existing wastewater treatment line have not been investigated. The Climate-KIC co-funded Microalgae Biorefinery 2.0 project developed and demonstrated this integration process through a case study. The purpose of this paper is to introduce this process by phases and protocols, as well as report on the challenges and bottlenecks identified in the case study. These standardized technical protocols detailed in the paper help to assess different aspects of integration including biological aspects such as strain selection, as well as economic and environmental impacts. This process is necessary to guide wastewater treatment plants through the integration of algae cultivation, as unfavourable parameters of the different wastewater related feedstock streams need specific attention and management. In order to obtain compelling designs, more emphasis needs to be put on the engineering aspects of integration. Well-designed integration can lead to operational cost saving and proper feedstock treatment enabling algae growth

Plasma miR-151-3p as a Candidate Diagnostic Biomarker for Head and Neck Cancer: A Cross-sectional Study within the INHANCE Consortium

Background: Identification of screening tests for the detection of head and neck cancer (HNC) at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating miRNAs for the diagnosis of HNC (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology consortium. Methods: A high-throughput screening phase with 754 miRNAs was performed in plasma samples of 88 cases and 88 controls, followed by a validation phase of the differentially expressed miRNAs, identified in the screening, in samples of 396 cases and 396 controls. Comparison of the fold changes (FC) was carried out using the Wilcoxon rank-sum test and the Dunn multiple comparison test. Results: We identified miR-151-3p (FC = 1.73, P = 0.007) as differentially expressed miRNAs in the screening and validation phase. The miR-151-3p was the only overexpressed miRNA in validation sample of patients with HNC with early stage at diagnosis (FC = 1.81, P = 0.008) and it was confirmed upregulated both in smoker early-stage cases (FC = 3.52, P = 0.024) and in nonsmoker early-stage cases (FC = 1.60, P = 0.025) compared with controls. Conclusions: We identified miR-151-3p as an early marker of HNC. This miRNA was the only upregulated in patients at early stages of the disease, independently of the smoking status. Impact: The prognosis for HNC is still poor. The discovery of a new diagnostic biomarker could lead to an earlier tumor discovery and therefore to an improvement in patient prognosis

Neurological assessment of newborns with spinal muscular atrophy identified through neonatal screening

The possibility to identify patients with spinal muscular atrophy through neonatal screenings has highlighted the need for clinical assessments that may systematically evaluate the possible presence of early neurological signs. The aim of this study was to use the Hammersmith Neonatal Neurological Examination (HNNE) and a module specifically designed for floppy infants to assess the possible variability of neurological findings in infants identified through neonatal screening. The infants included in this study were identified as part of a pilot study exploring neonatal screening in two Italian regions. A neurological examination was performed using the HNNE and an additional module developed for the assessment of floppy infants. Seventeen infants were identified through the screening. One patient had 1 SMN2 copy, 9 had 2 copies, 3 had 3, and 4 had more than 3 copies. Nine of the 17 infants (53%) had completely normal results on both scales, 3 had minimal signs, and the other 5 had more obvious clinical signs. The number of SMN2 copies was related to the presence of abnormal neurological signs (p = 0.036) but two SMN2 copies were associated with variable clinical signs as they were found in some infants with respectively normal examination or obvious severe early signs. Conclusions: Our results suggest that the combination of both scales increases the possibility to detect neonatal neurological signs and to define different early patterns of involvement also identifying paucisymptomatic patients.What is Known:• The use of new therapeutic options in presymptomatic SMA patients leads to a dramatic reduction of the onset and severity of the diesease.• The already existing tools commonly used in Type I SMA (HINE and CHOP-intend) may not be suitable to identify minor neurological signs in the neonatal period.What is New:• Combining the HNNE and the floppy infant module, we were able to identify early neurological signs in SMA infants identified through newborn screening&nbsp;and may help to predict the individual therapeutic outcome of these patients.• Iinfants with 2 SMN2 copies identified through the screening had a more variable neonatal examination compared to those with three or more copies, in agreement with similar findings in older infants

Plasma miR-151-3p as a candidate diagnostic biomarker for head and neck cancer: a cross-sectional study within the INHANCE consortium

Identification of screening tests for the detection of head and neck cancer at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating microRNAs for the diagnosis of head and neck cancer (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology (INHANCE) consortium

Microalgae biomass as an alternative ingredient in cookies: sensory, physical and chemical properties, antioxidant activity and in vitro digestibility

Microalgae can be regarded as an alternative and promising food ingredient due to their nutritional composition, richness in bioactive compounds, and because they are considered a sustainable protein source for the future. The aim of this work was to evaluate microalgae (Arthrospira platensis F & M-C256, Chlorella vulgaris Allma, Tetraselmis suecica F & M-M33 and Phaeodactylum tricornutum F & M-M40) as innovative ingredients to enhance functional properties of cookies. Two biomass levels were tested and compared to control: 2% (w/w) and 6% (w/ w), to provide high levels of algae-bioactives. The cookies sensory and physical properties were evaluated during eight weeks showing high color and texture stability. Cookies prepared with A. platensis and C. vulgaris presented significantly (p < 0.05) higher protein content compared to the control, and by sensory analysis A. platensis cookies were preferred. Besides, A. platensis also provided a structuring effect in terms of cookies texture. All microalgae-based cookies showed significantly higher (p < 0.05) total phenolic content and in vitro antioxidant capacity compared to the control. No significant difference (p < 0.05) in in vitro digestibility between microalgae cookies and the control was foundinfo:eu-repo/semantics/publishedVersio

Light emitting diodes (LEDs) applied to microalgal production.

Light-emitting diodes (LEDs) will become one of the world's most important light sources and their integration in microalgal production systems (photobioreactors) needs to be considered. LEDs can improve the quality and quantity of microalgal biomass when applied during specific growth phases. However, microalgae need a balanced mix of wavelengths for normal growth, and respond to light differently according to the pigments acquired or lost during their evolutionary history. This review highlights recently published results on the effect of LEDs on microalgal physiology and biochemistry and how this knowledge can be applied in selecting different LEDs with specific technical properties for regulating biomass production by microalgae belonging to diverse taxonomic groups