Preparation of the Enzymatic Hydrolysates from Chlorella vulgaris Protein and Assessment of Their Antioxidant Potential Using Caenorhabditis elegans.

This study aimed to assess the antioxidant potential of Chlorella vulgaris protein-derived enzymatic hydrolysate using Caenorhabditis elegans. Protein extraction was performed using an alkali solution after complete C. vulgaris swelling and hydrolysis using four commercial proteases (alcalase, neutrase, protamex, and flavourzyme). The results showed that the flavourzyme hydrolysates exhibited the strongest antioxidant activity both in vitro and in vivo. Under the optimum conditions of the enzymatic hydrolysis, the half-maximal effective concentration of the hydrolysates for superoxide and hydroxyl radicals was 0.323 mg/mL and 0.139 mg/mL, respectively. The hydrolysates could significantly extend the lifespan, improve the resistance to methyl viologen-induced oxidative stress, reduce the levels of reactive oxygen species, and enhance the activity of catalase and superoxide dismutase in C. elegans.

A guide to Open-JIP, a low-cost open-source chlorophyll fluorometer.

Chlorophyll a fluorescence is the most widely used method to study photosynthesis and plant stress. While several commercial fluorometers are available, there is a need for a low-cost and highly customisable chlorophyll fluorometer. Such a device would aid in performing high-throughput assessment of photosynthesis, as these instruments can be mass-produced. Novel investigations into photosynthesis can also be performed as a result of the user's ability to modify the devices functionality for their specific needs. Motivated by this, we present an open-source chlorophyll fluorometer based on the Kautsky induction curve (OJIP). The instrument consists of low-cost, easy-to-acquire electrical components and an open-source microcontroller (Arduino Mega) whose performance is equivalent to that of commercial instruments. Two 3D printable Open-JIP configurations are presented, one for higher plants and the other for microalgae cells in suspension. Directions for its construction are presented and the instrument is benchmarked against widely used commercial chlorophyll fluorometers.

Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry for the determination of selenomethionine and selenocysteine in algae and yeast.

In this work we present a simple and cost-effective approach for the determination of selenium species in algae and yeast biomass, based on a combination of thin-layer chromatography (TLC) with diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). Extraction of freeze-dried biomass was performed in 4M methanesulphonic acid and the selenium species were vaporized from cellulose TLC plates employing a continuous-wave infrared diode laser with power up to 4 W using a simple laboratory-built apparatus. Selenomethionine and selenocysteine were quantified with limits of detection 3 µg L-1 in a Se-enriched microalgae Chlorella vulgaris and yeast certified reference material SELM-1. Results delivered by TLC-DLTV ICP MS were consistent with those obtained by a routine coupling of high-performance liquid chromatography (HPLC) to ICP MS. In addition, the TLC approach is capable of analyzing extract containing even undiluted crude hydrolysates that could damage HPLC columns.

Low cost ionic liquid-water mixtures for effective extraction of carbohydrate and lipid from algae.

Biomass based biofuels are already an important energy source, and will increasingly be so in the future as the need for renewable energy rises. Due to their fast multiplication rates, algae can provide a sustainable supply of biomass, and are attractive because they do not compete with food crops for habitat. Here we show that biomass derived from Chlorella vulgaris and Spirulina platensis can be pretreated with low cost choline amino acid based ionic liquids to effectively yield lipids (30.6% and 51% total lipids) and sugars (71% and 26% total sugars). The ionic liquids dissolve the lipids, leaving behind a carbohydrate rich solid. The lipids were extracted with hexane, and the solid was subjected to enzyme hydrolysis to release fermentable sugars. These results open new pathways towards the dual production of biodiesel and bioethanol from algae, using low cost ionic liquids.

Optimization of ferric chloride concentration and pH to improve both cell growth and flocculation in Chlorella vulgaris cultures. Application to medium reuse in an integrated continuous culture bioprocess.

Combined effect of ferric chloride and pH on Chlorella vulgaris growth and flocculation were optimized using DoE. Afterwards, an integrated bioprocess for microalgae cultivation and harvesting conceived as a sole step was run in continuous operation mode. Microalgae concentration in a 2L-photobioreactor was about 0.5gL(-1) and the efficiency of flocculation in the coupled sedimentation tank was about 95%. Dewatered microalgae reached a biomass concentrations increase about 50-fold, whereas it was only about 0.02gL(-1) in the clarified medium. Then, the reuse of the clarified medium recovered was further evaluated. The clarified medium was reused without any further nutrient supplementation, whereas a second round of medium reuse was performed after supplementation of main nutrients (phosphate-sulfate-nitrate), micronutrients and ferric chloride. The medium reuse strategy did not affect cell growth and flocculation. Consequently, the reuse of medium reduces the nutrients requirements and the demand for water, and therefore the production costs should be reduced accordingly.

Toxicological, phytochemical, and antibacterial assessment of Chlorella vulgaris and Spirulina platensis powder in albino rats. A preliminary study

Objectives: To describe acute toxicity, antibacterial activity and phytochemical assessment of Chlorella vulgaris and Spirulina platensis powders. Material and Methods: FeCl3 test, Wagner test, Keller Killiani test, frothing test, alkaline solution and dilute acid; concentrated sulphuric acid were used for phytochemical analysis. Antibacterial screening of the extracts was conducted using the disc gel diffusion method in E. coli, S. aureus and B. cereus clinical strains. In order to evaluate acute toxicity and its effects on haematological and biochemical parameters; 15 albino rats were grouped into five groups: I (powder of aqueous extract of Chlorella vulgaris), II (powder of methanol extract of Chlorella vulgaris), III (powder of aqueous extract of Spirulina platensis), IV (powder of methanol extract of Spirulina platensis) and V (control). The dosage was 25g/day/rat. After six days, haematological and biochemical parameters and gross pathologic changes were evaluated. Results: Alkaloids and flavonoids were detected from the methanol extracts of both Chlorella vulgaris and Spirulina platensis (Arthrospira). Only cardiac glycosides and steroids were detected from Spirulina's extracts. Chlorella vulgaris extracts significantly inhibited B. cereus. Rats fed with Chlorella vulgaris and Spirulina platensis powder showed an increase in white blood cell counts and haemoglobin level compared to negative control rats (p<0.001). Serum glumatic oxalate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) had normal values but significative differences between groups (p<0.001). Conclusion: This powder is rich in bioactive phytochemicals but only Chlorella's extracts have shown antibacterial effect. Signs of toxicity weren't found in any parameter.

Objetivos: Describir la toxicidad aguda, efecto antibacteriano y análisis fitoquímico de los polvos de Chlorella vulgaris y Spirulina platensis. Materiales y métodos: Se realizaron las pruebas de FeCl3, Keller Killiani, de saponinas, solución alcalina y de concentración de ácido sulfúrico para el análisis fitoquímico. El efecto antibacteriano de los extractos fue evaluado mediante el método de difusión con discos en cepas de E. coli, S. aureus y B. cereus. Para evaluar la toxicidad aguda y los efectos del polvo en parámetros hematológicos y bioquímicos, se agruparon 15 ratas albinas en cinco grupos: I (polvo de extracto acuoso de Chlorella vulgaris); II (polvo de extracto metanólico de Chlorella vulgaris); III (polvo de extracto acuoso de Spirulina platensis); IV (polvo de extracto metanólico de Spirulina platensis), y V (grupo control). La dosis usada fue de 25 g/día/rata. Después de seis días, se evaluaron todos los parámetros y cambios macroscópicos en los órganos. Resultados: Se encontraron alcaloides y flavonoides en los extractos metanólicos de Chlorella vulgaris y Spirulina platensis (Arthrospira). Se detectaron glucósidos cardiacos y esteroides en los extractos de Spirulina platensis. Los extractos de Chlorella vulgaris inhibieron el crecimiento de Bacillus cereus. Las ratas alimentadas con los polvos de Chlorella vulgaris y Spirulina platensis incrementaron el conteo de leucocitos y los valores de hemoglobina comparados con el grupo control (p<0,001). Las transaminasas (SGOT y SGPT) se encontraron en valores normales, pero con diferencias significativas entre los grupos (p<0,001). Conclusiones: Estos polvos son ricos en componentes fitoquímicos activos, pero solo los extractos de Chorella vulgaris mostraron efecto antibacteriano. No se encontraron signos de toxicidad aguda en ningún parámetro.

A cost analysis of microalgal biomass and biodiesel production in open raceways treating municipal wastewater and under optimum light wavelength.

Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

Rapid, colorimetric quantification of lipid from algal cultures.

Algae have significant potential as a source of biomass for the production of biofuels, due to their high growth rates and high cellular lipid content. Studies that address the use of algae as biofuels often require the frequent measurement of algal lipid content. Traditional methods for the quantification of lipid are, however, costly if sub-contracted, or involve the use of expensive analytical equipment that is not available in many labs. This study describes a simple, colorimetric method for the quantification of algal lipid from small amounts of culture. The technique is derived from a method for the quantification of fatty acids dissolved in chloroform. Algal lipids are saponified to fatty acids and then mixed with a copper reagent. Chloroform-extractable copper soaps of long-chain fatty acids are then colorimetrically measured by the addition of diethyldithiocarbamate to develop a yellow colored product. Linear responses for fatty acids in the range of C10:0 to C16:0 were observed for a concentration range between 0.025 and 1 micromol of fatty acid per 200 microL of sample. Fatty acids with chain lengths of less than twelve carbons produced significantly reduced signal. Decenoic acid yielded a slightly, but significantly lower signal than decanoic acid indicating that the assay underestimates the presence of unsaturated fatty acids. Lipid contents of Phaeodactylum tricornutum and Chlorella vulgaris CM2 were monitored for eight days during exponential growth to demonstrate the feasibility of the technique as a monitoring methodology. Overall, the method allowed reliable detection and quantification of fatty acid content from 1 to 2 mL of algal culture. Adaptation of the technique to micro-centrifuge format allows assaying 30 samples in less than 2h. Considering reagents and time, the total cost per assay was estimated at less than $5, representing a significant cost savings over traditional lipid quantification procedures.

Simultaneous flue gas bioremediation and reduction of microalgal biomass production costs.

A flue gas originating from a municipal waste incinerator was used as a source of CO(2) for the cultivation of the microalga Chlorella vulgaris, in order to decrease the biomass production costs and to bioremediate CO(2) simultaneously. The utilization of the flue gas containing 10-13% (v/v) CO(2) and 8-10% (v/v) O(2) for the photobioreactor agitation and CO(2) supply was proven to be convenient. The growth rate of algal cultures on the flue gas was even higher when compared with the control culture supplied by a mixture of pure CO(2) and air (11% (v/v) CO(2)). Correspondingly, the CO(2) fixation rate was also higher when using the flue gas (4.4 g CO(2) l(-1) 24 h(-1)) than using the control gas (3.0 g CO(2) l(-1) 24 h(-1)). The toxicological analysis of the biomass produced using untreated flue gas showed only a slight excess of mercury while all the other compounds (other heavy metals, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans, and polychlorinated biphenyls) were below the limits required by the European Union foodstuff legislation. Fortunately, extending the flue gas treatment prior to the cultivation unit by a simple granulated activated carbon column led to an efficient absorption of gaseous mercury and to the algal biomass composition compliant with all the foodstuff legislation requirements.