This paper reviews some of the most important aspects of microalgae as a potential source for biodiesel production. Microalgae are photosynthetic microorganisms that can grow rapidly in a variety of environments because of their unicellular or multicellular structure depending on the species. They have the advantage of self-reproduction using solar energy and converting it into chemical energy via photosynthesis. This process concludes a full cycle in a few days, obtaining higher lipid yields than terrestrial crops. This review shows several techniques and some methodologies used in the biodiesel production process from microalgae as well as the challenges that must be overcome for large-scale process and in bio-refineries. Copyright © 2016 John Wiley & Sons, Ltd.

Background: Due to the problems we face today, such as wastewater pollution of aquifers and climate change, it is necessary to search for environmental solutions that help us minimize this problem. An alternative solution might be the cultivation of microalgae that are efficient in the purification of wastewater, removal of greenhouse gases and production of biomass that can be used for the production of biofuels such as biodiesel, methane, bioethanol, among others. The aim of this work is to cultivate five strains of microalgae native in Mexico: Chlorella miniata, Coelastrella sp., Desmodesmus quadricauda, Neochloris oleoabundans and Verrucodesmus verrucosus. The cultivations were performed using municipal wastewater and a foliar fertilizer with the further purpose of assessing their capacity to produce various types of biomass, in particular lipids. Methods: The experiments were carried out using triplicate 16-L glass bioreactors assays with a 12:12 light–darkness cycle at 25 °C ± 1 under constant aeration. Every 3rd day, a 1-mL sample was taken to determine cell density. In the stationary growth phase, each culture was harvested by sedimentation and lipid content analysis was performed. The biomass with the highest concentration of total lipids was subjected to an analysis of the methyl esters of fatty acids. Results: An ANOVA test showed significant differences between the growth rates (F = 6.8, p = 0.0001). The species that were able to produce biomass with the highest concentrations of total lipids were Coelastrella sp. with 44–46%; Verrucodesmus verrucosus with 43–44% and Neochloris oleoabundans 35–37%. As the analysis of the methyl esters of fatty acids showed, the species Coelastrella sp. and V. verrucosus produced lipids composed of 82.9% and 91.28% of fatty acids, respectively, containing C16–C18 carbon chains. Conclusions: All the species used in the present study were able to grow on wastewater and produce high concentrations of lipids. Therefore, the demands for biodiesel production could be met in the immediate future after continuing working with different microalgae species. Therefore, it is necessary to determine their adaptation potential to grow on contaminated effluents and produce lipids that can be used for the benefit of people and environment.

During a phytoplankton survey, non-motile (cyst-like) cells were isolated and cultured from the tropical Mexican Pacific, which belong to the thecate dinoflagellate Vulcanodinium rugosum Nézan et Chomérat, recently described from the Mediterranean and recently identified as a source of pinnatoxins in Australia, New Zealand, and Japan. Motile cells and putative cysts were studied by light microscopy and scanning electron microscopy. The most characteristic features of the species agree with a previous description: (i) large and conspicuous apical pore, which extrudes mucilaginous material; (ii) polygonal and striated theca; (iii) ventral, sigmoid canal running from the apical pore to the anterior margin of the cingulum; (iv) three connected anterior intercalary plates; and (v) production of spherical cyst-like cells. The species is photosynthetic, containing many small greenish-brown chloroplasts. The tabulation of the species is Po, X, 4′, 3a, 7″, 6c, 5s?, 5′″, 2″″. Organic cyst-like cells were nearly spherical to subspherical, solitary, or aggregations linked by mucilaginous material; they are considered to be a stage in the life cycle of the species. Vulcanodinium rugosum is a new record in the study area. The ecology and the geographical distribution of the species are also discussed.