This research presents the effect of hydrodynamic conditions at different rates of aeration (1.4, 1.8, and 2.3 vvm) and the geometry of two photobioreactors with internal lighting on lipid productivity and other parameters of Chlorella vulgaris. A two-step nitrogenreduction cultivation mode was applied for promoting lipid accumulation. The inoculum was cultivated initially at 90 mg L −1 N-NH 4 + , and at the end of the exponential phase, it was fed to 11 L photobioreactor at 20 mg L −1 of N-NH 4 +. The results showed that with similar aeration rates, the hydrodynamic regime in both photobioreactors was different. However, the increase in shear rate and agitation did not cause cell damage or photoinhibition. The maximum cell growth was 12 × 10 6 cells mL −1. The highest consumption of nitrogen was 19% and shear rates were of 120-340 s −1. The highest lipid productivity was reached in bubble column at 1.8 vvm with 0.650 mg•L −1 d −1 .

Fermentation technologies have been developed to improve the production of ethanol and an alternative is the immobilization technology, which ofers the possibility of eiciently incorporating symbiotic bacteria in the same matrix. This study analyzes the potential use of immobilized and coinmobilized systems on beads of calcium alginate for ethanol production used mango waste (Mangifera indica) by Zymomonas mobilis and Saccharomyces cerevisiae compared with free cells culture and evaluate the efect of glucose concentration on productivity in coimmobilized system using a Chemostat reactor Ommi Culture Plus. For free cell culture, the productivity was higher for Z. mobilis ). The conversion of glucose to ethanol for coimmobilized system was higher (6.91 mol ethanol) with 50 g L -1 of glucose compared to 200 g L -1 of glucose (5.82 mol ethanol); suggesting the immobilized and coimmobilized cultures compared with free cells ofer an opportunity for the reuse of organic residues and high alcohol production.

There is ongoing research related to the production of molecular hydrogen today and algae have proven to be good biological models for producing several compounds of interest. We analyzed how genetic variations in hydrogenase genes (hyd) can affect the production of molecular hydrogen in the algae Chlorella vulgaris and Scenedesmus obliquus. Through isolation and genetic characterization of hyd genes in S. obliquus and C. vulgaris, we made in-silico 3D modeling of the hydrogenase proteins and compared these in 11 algal genera. The 3D structure of hydrogenases indicated its structural conservation in 10 genera of algae, and the results of our grouping according to the aa characteristics of the proteins showed the formation of two groups, which were unrelated to the algae’s phylogenetic classification. By growing C. vulgaris and S. obliquus in anaerobic conditions (in darkness) during 24 h and after exposing the cultures to light, we observed H2 production values of 9.0 ± 0.40 mL H2/L and 16 ± 0.50 mL H2/L, respectively. The highest global relative expression of hyd genes was reached during the first 30 min of exposure to light. The behavior of the expression of the hyd genes in these species of algae proved to be species specific and involved in the production of H2. Future identification of isoforms of hyd genes in algae would allow a better understanding of the regulation of the hydrogenase enzyme.