Microalgae Research Papers - Academia.edu (original) (raw)

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions was evaluated using a modified low-cost Zarrouk medium. Growth was monitored... more

A two-phase outdoor cultivation bioprocess for Arthrospira maxima LJGR1 combined with phycocyanin induction in concentrated cultures under controlled conditions was evaluated using a modified low-cost Zarrouk medium. Growth was monitored during 4 cycles in 2018 and 4 cycles in 2019. Biomass was harvested and concentrated using membrane technology at the end of each cycle for further phycocyanin induction using blue LED light (controlled conditions, 24 h). The highest biomass productivity was observed during spring and summer cycles (13.63-18.97 g DW m −2 d −1); during mid-fall and mid-end fall, a decrease was observed (9.93-7.76 g DW m −2 d −1). Under favorable growth conditions, phycocyanin induction was successful. However, during cycles with unfavorable growth condition, phycocyanin induction was not observed. Reactive-grade phycocyanin (3.72 ± 0.14) was recovered and purified using microfiltration and ultrafiltration technologies.

The increasing water pollution caused by the presence of nano- and microplastics has shown a need to pursue solutions to remediate this problem. In this work, an extracellular polymeric substance (EPS) producing freshwater Cyanothece sp.... more

The increasing water pollution caused by the presence of nano- and microplastics has shown a need to pursue solutions to remediate this problem. In this work, an extracellular polymeric substance (EPS) producing freshwater Cyanothece sp. strain was exposed to nano- and microplastics. The bioflocculant capacity of the biopolymer produced was evaluated. The influence of different concentrations (1 and 10 mg L−1) of polystyrene nano- and microplastics in the extracellular carbohydrates and in the EPS production was studied. The presence of nano- and microplastics induced a negative effect on the microalgal growth (of up to 47%). The results show that the EPS produced by Cyanothece sp. exhibits high bioflocculant activity in low concentrations. Also, the EPS displayed very favourable characteristics for aggregation, as the aggregates were confirmed to consist of microalga, EPS and both the nano- and microplastics. These results highlight the potential of the microalgal-based biopolymers to replace hazardous synthetic flocculants used in wastewater treatment, while aggregating and flocculating nano- and microplastics, demonstrating to be a multi-purposed, compelling, biocompatible solution to nano- and microplastic pollution.

The upsurge in the concerning issues like global warming, environmental pollution and depletion of fossil fuel resources led to the thrust on third generation biofuels. Algal research has gained a lot of importance in the recent years.... more

The upsurge in the concerning issues like global warming, environmental pollution and depletion of fossil fuel resources led to the thrust on third generation biofuels. Algal research has gained a lot of importance in the recent years. Effective utilization of algal biomass in a single step is necessary as it can produce Bio-oil (BO), gases and in addition to a variety of valuable products, along with nutrient recovery. Hydrothermal liquefaction technology does not require the energy intensive drying steps and is an attractive approach for the conversion of algae to liquid fuels. This study investigates direct hydrothermal liquefaction (HTL) of microalgae (Algal bio-mass) to produce bio-oil using a high-pressure batch reactor under subcritical water conditions. Three different micro algae samples namely, Chlorella vulgaris, Botryococcus braunii and Scenedesmus quadricauda have been examined under hydrothermal liquefaction with different water concentrations (1:6, 1:7, 1:8, 1:9 & 1:10 ratio) at certain temperature range (200-320 °C), pressure (60 bars) and reaction time (30 min). Through liquefaction, the highest BO yield achieved with S. quadricauda was 18 wt% at 1:9 ratio. The chemical components of the obtained bio-oil were analyzed via gas chromatography and the results indicated that the algal BO was composed of furan, phenol, acid, and ester derivatives. Moreover, it was found that by increasing the temperatures, the BO yields increased. This was due to the polymerization reactions that converted the small biomass components into heavier molecules. FTIR spectra showed high percentage of Aliphatic, Phenolic, alcoholic, Carboxylic and Hydroxyl groups for solid residues.

La alta demanda de plásticos como el PET y el escaso conocimiento sobre la economía verde o el reciclaje ha incrementado los efectos adversos al medio ambiente por acumulación incontrolada de residuos plásticos que terminan en las fuentes... more

La alta demanda de plásticos como el PET y el escaso conocimiento sobre la economía verde o el reciclaje ha incrementado los efectos adversos al medio ambiente por acumulación incontrolada de residuos plásticos que terminan en las fuentes hídricas. Dentro de las estrategias que se han estudiado para controlar este problema, la degradación mediante microorganismos ha dado óptimos resultados en eficiencia y economía. Mediante una revisión bibliográfica, se especifica el mecanismo (enzimas) para la degradación del PET, teniendo en cuenta las principales condiciones de cultivo y del microorganismo, el pretratamiento que se debe realizar al PET y los porcentajes de degradación alcanzados. También se presentan las aplicaciones industriales de los posibles subproductos para su aprovechamiento y disminución de la contaminación.

New practices linked to biological sciences are emerging in the world of design and architecture. In recent years various interventions have involved the use of living organisms and biomaterials even in an urban context. This essay... more

New practices linked to biological sciences are emerging in the world of design and architecture. In recent years various interventions have involved the use of living organisms and biomaterials even in an urban context. This essay analyzes those projects that have entailed the use of microalgae, tracing their limits and possibilities. The guidelines for the implementation of similar projects at the level of products or small installations are also defined. From the perspective of designing for the benefit of citizens and given the countless properties of microalgae, solutions of this kind and innovative integrated services could be a way to mitigate the environmental, but also social and economic problems, of present and future cities.

The effect of specific narrow light-emitting diode (LED) wavelengths (red, green, blue) and a combination of LED wavelengths (red, green and blue - RGB) on biomass composition produced by Porphyridium purpureum is studied.... more

The effect of specific narrow light-emitting diode (LED) wavelengths (red, green, blue) and a combination of LED wavelengths (red, green and blue - RGB) on biomass composition produced by Porphyridium purpureum is studied. Phycobiliprotein, fatty acids, exopolysaccharides, pigment content, and the main macromolecules composition were analysed to determine the effect of wavelength on multiple compounds of commercial interest. The results demonstrate that green light plays a significant role in the growth of rhodophyta, due to phycobiliproteins being able to harvest green wavelengths where chlorophyll pigments absorb poorly. However, under multi-chromatic LED wavelengths, P. purpureum biomass accumulated the highest yield of valuable products such as eicosapentaenoic acid (∼2.9%DW), zeaxanthin (∼586 μg g− 1 DW), β-carotene (397 μg g− 1 DW), exopolysaccharides (2.05 g/L-1), and phycobiliproteins (∼ 4.8% DW). This increased accumulation is likely to be the combination of both photo-adaption and photo-protection, under the combined specific wavelengths employed.

Quality characteristics of wheat are determined by different physiochemical and rheological analysis by using different AACC methods. AACC methods are expensive, time consuming and cause destruction of samples. Fourier transforms infrared... more

Quality characteristics of wheat are determined by different physiochemical and rheological analysis by using different AACC methods. AACC methods are expensive, time consuming and cause destruction of samples. Fourier transforms infrared (FTIR) spectroscopy is one of the most important and emerging tool used for analyzing wheat for different quality parameters. This technique is rapid and sensitive with a great variety of sampling techniques. In the present study different wheat varieties were analyzed for quality assessment and were also characterized by using AACC methods and FTIR technique. The straight grade flour was analyzed for physical, chemical and rheological properties by standard methods and results were obtained. FTIR works on the basis of functional groups and provide information in the form of peaks. On basis of peaks the value of moisture, protein, fat, ash, carbohydrates and hardness of grain were determined. Peaks for water were observed in the range 1,640 cm−1 and 3,300 cm−1 on the basis of functional group H and OH. Protein was observed in the range from 1,600 cm−1 to 1,700 cm−1 and 1,550 cm−1 to 1,570 cm−1 on the basis of bond amide I and amide II respectively. Fat was also observed within these ranges but on the basis of C-H bond and also starch was observed in the range from 2,800 and 3,000 cm−1 (C-H stretch region) and in the range 3,000 and 3,600 cm−1 (O-H stretch region). As FTIR is a fast tool it can be easily emplyed for wheat varieties identification according to a set criterion.

Recombinant protein production in microalgae chloroplasts can provide correctly folded proteins in significant quantities and potentially inexpensive costs compared to other heterologous protein production platforms. The best results have... more

Recombinant protein production in microalgae chloroplasts can provide correctly folded proteins in significant quantities and potentially inexpensive costs compared to other heterologous protein production platforms. The best results have been achieved by using the psbA promoter and 5' untranslated region (UTR) to drive the expression of heterologous genes in a psbA-deficient, non-photosynthetic, algal host. Unfortunately, using such a strategy makes the system unviable for large scale cultivation using natural sunlight for photosynthetic growth. In this study we characterized eight different combinations of 5' regulatory regions and psbA coding sequences for their ability to restore photosynthesis in a psbA-deficient Chlamydomonas reinhardtii, while maintaining robust accumulation of a commercially viable recombinant protein driven by the psbA promoter/5'UTR. The recombinant protein corresponded to bovine Milk Amyloid A (MAA), which is present in milk colostrum and coul...

Literature data on biosynthesis, qualitative and quantitative diversity, involvement in the regulation of physiological and biochemical processes, prospects for use of microalgae cytokinins (CKs) and gibberellins (GA) in biotechnological... more

Literature data on biosynthesis, qualitative and quantitative diversity, involvement in the regulation of physiological and biochemical processes, prospects for use of microalgae cytokinins (CKs) and gibberellins (GA) in biotechnological developments have been analyzed and summarized. Forty-five (45) microalgae species, belonging to 5 divisions, have 37 forms of CKs. The qualitative composition and quantitative content of microalgae CKs are shown to be strongly affected by light conditions and by the presence of an energy source in the culture medium. The main biological functions of microalgae CKs include stimulation of cell division, activation of growth processes, and increased photosynthetic activity. Microalgae cytokinin protective properties that provide protection for cell divisions and the photosynthetic apparatus under stress conditions are revealed. The problem of microalgae cytokinins biosynthesis is still controversial, and their interactions with other phytohormone classes need further investigation. Gibberellins were discovered in 31 microalgae species: 20 hormone isoforms were identified. Microalgae GA physiological effects are similar to those of higher plants, and in a lag phase exhibit reduction and stimulation of cell growth and division, increase in biomass, accumulation of proteins and pigments, and reduction of heavy metal effects

El objetivo de esta investigación es producir biodiesel a partir de aceite microalgal obtenido de la especie Chlorella vulgaris cultivada en efluentes de una planta de tratamientos de aguas residuales en condiciones de laboratorio. A la... more

El objetivo de esta investigación es producir biodiesel a partir de aceite microalgal obtenido de la especie Chlorella vulgaris cultivada en efluentes de una planta de tratamientos de aguas residuales en condiciones de laboratorio. A la biomasa obtenida después del periodo de cultivo se le extrae el contenido lipídico mediante el método químico “Soxhlet”, se realiza la bioconversión a biodiesel mediante el método de transesterificación. La máxima concentración celular alcanzada en los primeros 11 días de cultivo fue de 1.153x 106 cel ml-1 en el efluente del reactor secundario. La densidad celular se mide mediante método directo en cámara de Neubauer y con curva patrón de Absorbancia contra peso seco de microalga a 680 nm. La extracción de lípidos por método Soxhlet presento un rendimiento del 10% en peso seco por cada 10 g de biomasa seca (0.192 g).

Digestate produced from the anaerobic digestion of food and farm waste is primarily returned to land as a biofertiliser for crops, with its potential to generate value through alternative processing methods at present under explored. In... more

Digestate produced from the anaerobic digestion of food and farm waste is primarily returned to land as a biofertiliser for crops, with its potential to generate value through alternative processing methods at present under explored. In this work, valorisation of a digestate resulting from the treatment of kitchen and food waste was investigated, using dilution, settlement and membrane processing technology. Processed digestate was subsequently tested as a nutrient source for the cultivation of Chlorella vulgaris, up to pilot-scale (800L). Dilution of digestate down to 2.5% increased settlement rate and induced release of valuable compounds for fertiliser usage such as nitrogen and phosphorus. Settlement, as a partial processing of digestate offered a physical separation of liquid and solid fractions at a low cost. Membrane filtration demonstrated efficient segregation of nutrients, with micro-filtration recovering 92.38% of phosphorus and the combination of micro-filtration, ultra-filtration, and nano-filtration recovering a total of 94.35% of nitrogen from digestate. Nano-filtered and micro-filtered digestates at low concentrations were suitable substrates to support growth of Chlorella vulgaris. At pilot-scale, the microalgae grew successfully for 28 days with a maximum growth rate of 0.62 day À1 and dry weight of 0.86 gÁL À1. Decline in culture growth beyond 28 days was presumably linked to ammonium and heavy metal accumulation in the cultivation medium. Processed digestate provided a suitable nutrient source for successful microalgal cultivation at pilot-scale, evidencing potential to convert excess nutrients into biomass, generating value from excess digestate and providing additional markets to the anaerobic digestion sector.

One of the main challenges for the successful production and use of microalgae for biodiesel production is to obtain a satisfactory level of fatty acid methyl esters (FAME). The aims of this study are to identify the best method of lipid... more

One of the main challenges for the successful production
and use of microalgae for biodiesel production is to
obtain a satisfactory level of fatty acid methyl esters (FAME).
The aims of this study are to identify the best method of lipid
extraction and provide high FAME levels and to evaluate their
fatty acid profiles. Six lipid extraction methodologies in three
microalgae species were tested in comparison with the direct
transesterification (DT) of microalgal biomass method. The
choice of extraction method affected both the oily extract yield
and the FAME composition of the microalgae and consequently
may affect the properties of biodiesel. The efficiency of different lipid extraction methods is affected by the solvent polarity, which extracts different target compounds from lipid matrix. Dichloromethane/methanol extraction and Folch extraction produced the largest oil extract yields, but extraction with hexane/ethanol resulted in the best ester profile and levels. Performing DT reduces the volume of extractor solvent, the time and cost of FA composition analysis, as well as, presents less steps for fatty acid quantification. DT provided biomass FAME levels of 50.2, 636.4, and 258.2 mg.g−1 in Nannochlorophisis oculata, Chaetoceros muelleri, and Chlorella sp., respectively. On the basis of an analysis of the fatty acids profiles of different species,
C. muelleri is a promising microalga for biodiesel production.
Depending on the extraction method, Chlorella sp. and N. oculata can be considered as an alternative in obtaining
arachidonic (Aa) and eicosapentaenoic (EPA) acids.