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Simultaneous bioproduction of hydrogen and ethanol from cheaper waste feedstock has the potential for the development of a more cost-effective biofuel generation process. Crude glycerol (CG), a by-product of the biodiesel industry, is a renewable resource, abundant, sold at low prices and available worldwide. However, the main CG limitations in fermentation processes are mainly related to the presence of impurities and the lack of nitrogen sources, both acting on microbial activity. In this study, a fermentation process with CG was improved using a highly specific microbial consortium called GlyCeroL (GCL). The process was developed in fed-batch fermentation mode using not diluted substrate and carried out under non-sterile conditions and at increasing amounts of the substrate (from 20 to 80 gL−1 of glycerol). The results showed higher H2 (from 6 to 8 LL−1) and EtOH (from 13 to 20 gL−1) production by increasing glycerol concentration from 20 to 40 gL−1. On the other hand, a decrease in glycerol degradation efficiency (from 75 to 56%) was observed. Then, the nitrogen sparging strategy was applied. Using CG of 40 gL−1, process improvement was achieved, leading to the increased production of hydrogen (10 LL−1) but not that of ethanol (20 gL−1). A further increase to 60 gL−1 of glycerol produced a slight increment of EtOH (21 gL−1) and H2 (11 gL−1) but a sharp decrease in glycerol degradation efficiency (41%). Acetate, as the main impurity of CG, was an additional carbon source for GCL microorganisms contributing to EtOH production and increasing that of lactic acid to restore the redox balance. The Denaturing Gradient Gel Electrophoresis (DGGE) fingerprint at the end of all fed-batch fermentations supported the robustness of GCL functional units and their adaptability to fermentation conditions. [ABSTRACT FROM AUTHOR]

Microalgae are among the most interesting eukaryotic photosynthethic microorganisms able to use solar energy, nutrients and carbon dioxide to convert them into proteins, carbohydrates, lipids and other valuable organic compounds including carotenoids. Astaxanthin is one of the most interesting antioxidant molecules which has attracted crescent interest due to its positive effects on health and the numerous applications in different sectors, from nutraceutical to cosmetic and aquaculture. Even though the astaxanthin properties are well-known, its price still remains high if associated to the algal form, exceeding ~6000 Eur/Kg. This can be explained by considering the process expenses related to the extraction and purification steps of microalga intracellular metabolites. In fact, the downstream stage of this biotechnological process often accounts for more than 60-70% of total production costs. Optimized extraction and purification operations might contribute to microalgae market with the advantage to commercialize a natural existing astaxanthin form. The aim of this paper is the evaluation of the use of commercial activated carbon Darco™ G-60 for the purification of astaxanthin from an extraction broth. Astaxanthin was firstly extracted from Haematococcus pluvialis red phase supplied by Micoperi Blue Growth, an Italian Company that is working for a long time and it is specialized in the microalgae growth. Extraction was performed by Accelerated Solvent Extractor (ASE®200 DIONEX) at 100 bar and 67°C by using ethanol as green solvent with the main advantage to separate all the unipolar fractions as well as insoluble fractions from astaxanthin extracts (fibers, carbohydrate, ashes). In the second step, astaxanthin was purified with a column filled with activated carbon. Experimental tests by changing the mass of activated carbon were carried out (50mg, 100mg and 200mg)and with a flow rate in the range 0.9-1.0ml/min. All the experimental tests were carried out at room temperature (20°C). Results showed that by using activated carbon, it is possible to obtain an adsorption capacity of DARCO G60 in the range 21,9-23,9 mg/g. [ABSTRACT FROM AUTHOR]

The request for natural products such as antioxidant pigments derived from microalgae, i.e. ß-carotene, lutein and astaxanthin, is growing. In this context, astaxanthin, a powerful antioxidant produced by Haematococcus pluvialis, used as an additive in animal feed and as a food supplement, has been extracted by accelerated solvent extraction using acetone and ethanol as green and safe solvents, and hexane and chloroform:methanol (1:1) performing the best operating conditions. The obtained extracts showed not only the recovery of mainly astaxanthin but also other carotenoids, such as lutein and in lesser part of ß-carotene. In addition, the composition of the extracts was analyzed by highlighting the content of other valuable bioproducts such as proteins, carbohydrates, lipids and Total Dietary Fibers. The best extraction performance was found using acetone and ethanol as solvent. [ABSTRACT FROM AUTHOR]

In this work, a membrane-based separation was investigate for Scenedesmus almeriensis solutions dewatering. A commercial polyvinylidene fluoride (PVDF) membrane, having a pore size of 3 µm was used in order to allow the water passage through it (permeate), retaining, at the same time, algae biomass (retentate). The possibility to reuse the permeate for a second Scenedesmus almeriensis growth step, was also studied. The registered data evidenced the feasibility of the membrane-based dewatering as an alternative competitive technology, even though the recovery of water should need further investigations to be optimized. [ABSTRACT FROM AUTHOR]

The omega-3 group includes substances as eicosapentaenoic acid and docosapentaenoic acid that can be partially synthesized by human body and substances as alpha-linolenic acid that have to be necessarily introduced into the body from dietary intake. Omega-3 are important nutrients thanks to their anti-inflammatory properties and healthy properties in the reduction of cardiovascular diseases. The growth forecasts of omega- 3 market will lead to an increase in the demand for EPA and DHA and therefore finding new potential sources, such as microalgae which are the first EPA and DHA producers in the marine environment, is very important. The aim of this work is to evaluate the feasibility of mechanical pretreatment on Nannochloropsis gaditana as source of EPA and at the same time evaluating the effect on the extraction yield of two solvents: a mixture of chloroform/methanol/water (Bligh & Dyer methods) and hexane that is GRAS (generally recognized as safe solvent) by using accelerated solvent extraction technology. [ABSTRACT FROM AUTHOR]