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Diatom algae are increasingly explored as an alternative sustainable source for functional biomolecules likes fucoxanthin, and eicosapentaenoic acid. But biomolecule quantity and quantity are influenced by growth conditions. So, effect of differential silica concentration (0-120 mg L

The large-scale cultivation of microalgae provides a wide spectrum of marketable bioproducts, profitably used in many fields, from the preparation of functional health products and feed supplement in aquaculture and animal husbandry to biofuels and green chemistry agents. The commercially successful algal biomass production requires effective strategies to maintain the process at desired productivity and stability levels. Hence, the development of effective early warning methods to timely indicate remedial actions and to undertake countermeasures is extremely important to avoid culture collapse and consequent economic losses. With the aim to develop an early warning method of algal contamination, the potentiometric E-tongue was applied to record the variations in the culture environments, over the whole growth process, of two unialgal cultures, Phaeodactylum tricornutum and a microalgal contaminant, along with those of their mixed culture. The E-tongue system ability to distinguish the cultures and to predict their growth stage, through the application of multivariate data analysis, was shown. A PLS regression method applied to the E-tongue output data allowed a good prediction of culture growth time, expressed as growth days, with R2 values in a range from 0.913 to 0.960 and RMSEP of 1.97–2.38 days. Moreover, the SIMCA and PLS-DA techniques were useful for cultures contamination monitoring. The constructed PLS-DA model properly discriminated 67% of cultures through the analysis of their growth media, i.e., environments, thus proving the potential of the E-tongue system for a real time monitoring of contamination in microalgal intensive cultivation.

A portable sensor for fluorescence spectroscopy of liquids has been developed. This sensor exploits the autofluorescence produced by organic chemical compounds when exposed to ultraviolet or visible light. In particular, the autofluorescence produced by pigments present in cyanobacteria and microalgae allow their in vivo detection. Liquid jet waveguide approach has been chosen in order to provide efficient fluorescence light collection. A mini-spectrophotometer is used as a detector and a mini-PC manages all the instrumentation. The whole sensor is housed inside a weather-proof plastic enclosure which allows it to be transported as hand luggage. The sensor can be equipped with three different LED sources that can be easily replaced according to the needs due to the type of substances intended to detect. Several sources at different wavelengths have been taken into consideration and characterized for this purpose. The excitation at multiple wavelengths provides the possibility of discrimination between different substances or phytoplankton groups. Preliminary measurements, using excitation wavelength at 275, 405 and 590 nm, show the possibility of detecting the presence of cyanobacteria in water collected at different pickup points in an aquaponics plant.

Microbial consortia are effective biofilters to treat wastewaters, allowing for resource recovery and water remediation. To reuse and save water in the domestic cycle, we assembled a suspended biofilm, a ‘biofilter’ to treat dishwasher wastewater. Bacterial monocultures of both photo- and heterotrophs were assembled in an increasingly complex fashion to test their nutrient stripping capacity. This ‘biofilter’ is the core of an integrated system (Zero Mile System) devoted to reusing and upcycling of reconditioned wastewater, partly in subsequent dishwasher cycles and partly into a vertical garden for plant food cultivation. The biofilter was assembled based on a strain of the photosynthetic, filamentous cyanobacterium Trichormus variabilis, selected to produce an oxygen evolving scaffold, and three heterotrophic aerobic bacterial isolates coming from the dishwasher wastewater itself: Acinetobacter, Exiguobacterium and Pseudomonas spp. The consortium was constructed starting with 16 isolates tested one-to-one with T. variabilis and then selecting the heterotrophic microbes up to a final one-to-three consortium, which included two dominant and a rare component of the wastewater community. This consortium thrives in the wastewater much better than T. variabilis alone, efficiently stripping N and P in short time, a pivotal step for the reuse and saving of water in household appliances.

In the last 20 years, we have witnessed increased interest in prospecting novel drugs from microalgae-derived bioactive metabolites. However, despite the conspicuous amount of literature about bioactivity screening of microalgal extracts, we have found few investigations focusing on the subsequent phases of the drug discovery process. We identify here the main critical aspects of the reported approaches, and suggest a number of experimental steps for moving beyond the current infancy state, in order to implement a more advanced microalgae-based drug discovery project. This might assist researchers in understanding microalgae systems, and their potential for therapeutic applications.

Microalgae bioprospecting indicates diatoms as a promising resource for biotechnology, with multiple extractions, and intermediate valorization protocols able to open new paths in biomedical, food and feed, and bioenergy fields. The biomass of two diatoms, Phaeodactylum tricornutum and Staurosirella pinnata, was sequentially extracted to obtain crude extracts, cellular lipids, and biomethane by means of compatible protocols. Hydrophilic fractions of crude extracts were characterized for their bioactivity on human melanoma (CHL-1) and keratinocytes (HaCaT) cell lines, with S. pinnata extract showing efficient anti-proliferative and cell death inducing activities only on CHL-1. Total lipids were extracted from residual biomass, and their chromatographic profiles evidenced percental amounts of eicosapentaenoic, hexadecenoic, and octadecanoic acid, exploitable in food and feed sectors. Finally, exhausted biomass was used for biomethane production, with P. tricornutum showing the highest rate. Cascade extraction from diatom biomass prospected potential to optimize the production of algal chemicals and their further biotechnological application.

A native strain of the heterocytous cyanobacterium Trichormus variabilis VRUC 168 was mass cultivated in a low-cost photobioreactor for a combined production of Polyunsaturated Fatty Acids (PUFA) and Exopolymeric Substances (EPS) from the same cyanobacterial biomass. A sequential extraction protocol was optimized leading to high yields of Released EPS (REPS) and PUFA, useful for nutraceutical products and biomaterials. REPS were extracted and characterized by chemical staining, Reversed Phase-High-Performance Liquid Chromatography (RP-HPLC), Fourier Transform Infrared Spectroscopy (FT-IR) and other spectroscopic techniques. Due to their gelation property, REPS were used to produce a photo-polymerizable hybrid hydrogel (REPS-Hy) with addition of polyethylene glycol diacrylated (PEGDa). REPS-Hy was stable over time and resistant to dehydration and spontaneous hydrolysis. The rheological and functional properties of REPS-Hy were studied. The enzyme carrier ability of REPS-Hy was assessed using the detoxification enzyme thiosulfate:cyanide sulfur transferase (TST), suggesting the possibility to use REPS-Hy as an enzymatic hydrogel system. Finally, REPS-Hy was used as a scaffold for culturing human mesenchymal stem cells (hMSCs). The cell seeding onto the REPS-Hy and the cell embedding into 3D-REPS-Hy demonstrated a scaffolding property of REPS-Hy with non-cytotoxic effect, suggesting potential applications of cyanobacteria REPS for producing enzyme- and cell-carrier systems.