## 2 Strain Selection
for phycocyanin and biomass for food applications; _Chlorella vulgaris_ for food applications and more [20]; the cyanobacteria _Aphanizomenon flos-aquae_ for the curative properties of its extract [6]; _Phaeodactylum tricrontum_ for production of fucoxanthin and eicosapentaenoic acid (EPA) rich oil [21]; _Euglena gracilis_ for protein, lipids, vitamins and beta-1,3-glucan [22]; _Nannochloropsis_ sp. for biomass, aquaculture, and EPA; _Porphyridium cruentum_ for exopolysaccharide production; and _Isochrysis_ sp. for aquaculture. In some cases, the industrial enterprises producing the biomass are not easy to identify due to not publicising their products openly, but instead marketing directly to multinational food/feed factories without disclosing the microalgae strains they are working with. However, the market is moving towards an expectation of greater transparency pushing such companies to share more information about the provenance of their products. The main properties that have led to the establishment and selection of these strains are: fast, reliable and robust growth under variable conditions; the ability to use a selective environment to \begin{table}
\begin{tabular}{c c c} \hline \hline
**Microalgae Strain** & **Main Product** & **Companies Involved in Biomass Production** \\ \hline _Aphanizomenon flos-aquae_ & Extract & Naturally-harvested [23] \\ \hline _Arthrospira platensis/maxima_ & Phycocyanin & Algaetech international [24], Cyanotech [25], DIC Corporation [26], Olivier MicroAlgues [27], Parry Nutraceuticalticals [28], Scotbio [29], Spira [30] \\ \hline _Chlorella vulgaris_ & Biomass & Allmicroalgae [31], Parry Nutraceuticalticals [28], Roquette [32], Taiwan Chlorella Manufacturing Company [33] \\ \hline _Dumaliella salina/bardawil_ & Beta caroten & InterClinical Laboratories [34], Monzonbiotech [35], Nature Beta Technologies [36] \\ \hline _Euglena gracilis_ & Beta-1,3-glucan & Algatech [22], Euglena Co [37] \\ \hline _Haematococcus pluvialis_ & Astaxanthin & AlgaeCan Biotech [38], Algaetech International [24], Algalif [39], Algamo [40], Algatech [21], AstaReal [41], Cyanotech [25], Heliae [42], Yunnan Gingko Ast Biotech [43] \\ \hline _Isochrysis_ sp. & Biomass & Archimede ricerche [44], Necton [45] \\ \hline _Nannochloropsis_ sp. & EPA & Algaspring [46], Algatech [21], Allmicroalgae [31], Archimede ricerche [44], Monzonbiotech [35], Necton [45] \\ \hline _Phaeodactylum tricrontutum_ & Fucoxanthin & Algatech [21], Necton [45] \\ \hline _Porphyridium cruentum_ & Exopolysaccharideaccharides & Algatech [21], Necton [45] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Selection of microalgae companies producing biomass. maintain culture stability (e.g., _Arthrospira platensis_ grows well in high pH medium which makes it easy to grow in open ponds with limited bacterial contamination); the composition of the biomass (high in lipids or protein or carbohydrate); the production of specific high value compounds (astaxanthin); physical and physiological robustness; susceptibility of the cells to lysis/desiccation/storage; resistance to predation. Crucially, many of the strains listed in Table 1 can now be genetically modified or are in the process of having protocols developed [47; 48; 49; 50; 51; 52; 53; 54; 55]. For fuel production, which has arguably dominated industrial-related microalgae research over the last couple of decades, the composition of fatty acids has always been deemed important, both quality and quantity. Microalgae provide a high proportion of unsaturated fatty acids (predominantly polar membrane lipids) and a significant content of saturated palmitic acid (C16:0; 17-40%). Among the undesirable unsaturated fatty acids, European Standard EN 14,214 (2004) specifies a limit of 12% for linolenic (C18:3) and 1% for polyunsaturated (\(\geq\)4 double bonds) contents for quality biodiesel.