Chlorella and Spirulina are the two of the most well-known microalgae genus. Both microalgae genus have a significant content of proteins, vitamins, pigments, fatty acids, sterols, among others, which make their production/application by the food industry quite interesting. Chlorella genus is a eukaryotic microorganism, whereas Spirulina genus (cyanobacteria) is a prokaryotic microorganism. The aim of this review was to provide an overview on Chlorella and Spirulina microalgae, particularly as an alternative source of functional foods, nutraceuticals, and food supplements, in which the following compound groups were addressed: (I) Long-Chain Polyunsaturated Fatty Acids; (II) Phenolic Compounds; (III) Volatile Compounds; (IV) Sterols; (V) Proteins, Amino Acids, Peptides; (VI) Vitamins; (VII) Polysaccharides; (VIII) Pigments and (IX) Food. Chlorella and Spirulina microalgae and their derivatives are concluded not to be widely commercially exploited. However, they are remarkable sources of functional foods, nutraceuticals and food supplements.

P. tsukubaensis is a yeast-like microorganism that synthesized the biosurfactant mannosylerythritol lipids-B (MEL-B). Production cost can be one of the drawbacks of biosurfactants production. Therefore the development of efficient and cost effective purification strategies and the use of by-products in the culture medium could serve as important strategies to reduce overall process cost. The aim of this work was to evaluate the production of MEL using cassava wastewater, a hydrophilic medium composed of a low-cost substrate which is a by-product of cassava processing, followed by foam fractionation and ultrafiltration of MEL. Cassava wastewater proved to be a feasible culture medium for P. tsukubaensis and MEL-B production as the yield (1.26 g L) was similar to that reported by others using water-soluble carbon sources (up to 2 g/L). Interestingly ultrafiltration with 100 KDa MWCO memabranes (using 20 mL centrifugal devices) led to the purification of MEL-B in one step since ≈ 80% of MEL was recovered, while more than 95% of proteins were found in the permeate. The scale up of the ultrafiltration (up to 500 mL) using a cross flow filtration unit led to very similar results. Overall the ultrafiltration led to a threefold increase in MEL purity in terms of protein (at both scales). The chemical characterisation by NMR confirmed the production of MEL-B homologue and also the production of a second stereoisomer ≈ 9%, while the CG-MS and MALDI-TOFMS analysis confirmed the main fatty acids within the structure of MEL-B (C8:0 and 12:0 and C8:0 and C14:1). Therefore, the process developed here was found to be a good alterntative to the conventional production of MEL which uses synthetic culture medium, solvent extraction (ethyl acetate) and column chromatography (silica) for its purification.

BACKGROUND Bacillus subtilis synthesizes surfactin, a powerful surface‐active agent. It has interesting potential applications. However, due to its high cost of production, commercial use is impracticable. The downstream processing represents ≈ 60% of production costs and the culture medium ≈ 30%. Many reports focused, separately, on production of surfactin using by‐products (reduced cost) or the purification using synthetic medium. Therefore, the aim of this work was to evaluate, for the first time, the impact of using a by‐product as fermentation medium on the downstream processing based on membrane filtration. RESULTS Membranes of PES‐100‐kDa efficiently retained surfactin micelles – the first step of ultrafiltration, whereas, the second step required membranes of 50 kDa to separate surfactin monomers from proteins. Ultrafiltration of crude biosurfactant was associated with fouling and/or concentration polarization resulting in lower purity than when synthetic medium was used. Further improvement in purity was achieved by partial removal of proteins before ultrafiltration by acid precipitation and extraction. The NMR and MALDI‐TOFMS analyses identified 11 potential surfactin homologues composed of two amino acid sequences. CONCLUSION Production of surfactin using cassava wastewater as a low‐cost culture medium and its purification by the 2‐step ultrafiltration process is feasible, nevertheless, the higher protein content of this medium compared with the synthetic one leads to a lower purity product; further increase in purity can be achieved by applying additional purification steps prior to ultrafiltration with subsequent increased process cost. © 2016 Society of Chemical Industry

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Therefore, the optimal matrix for the analysis of protein from intact microalgae cells is sDHB with TA50 as the matrix solvent and without isopropanol. These conditions allow the acquisition of high quality spectrum profiles.

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