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.

Abstract. Recently, there is growing interest in obtaining bioactive compounds from species in the family Cactaceae, which has been little analyzed at the genomic and transcriptomic level. We here report the assembly of the genome of Cereus fernambucensis and we analyzed six cactus genomes (Carnegiea gigantea, Lophocereus schottii, Pachycereus pringlei, Pereskia humboldtii, Selenicereus undatus and Stenocereus thurberi), the annotation of putative genes, and the modeling of the three-dimensional structures of their predicted proteins involved in flavonoid metabolism. We identified genes encoding proteins related to plant pathogenesis (PR-10), coding secuences (CDS) of aldehyde reductase and flavonoid reductase, CDS of enzymes involved in the biosynthesis of phenolic compounds, and ABC transporters. The grouping of the enzymes aspartic proteinase-like protein, flavanone 3-hydroxylase (F3H), hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT), and protein serine/threonine- phosphatase was shown to be highly conserved in the genomes of the analyzed cacti. We found divergence of the plant PDR ABC-type transporter family protein (PEN3) in Cereus fernambucensis and the absence in this species of sterol methyltransferase (SMT1). Our three-dimensional modeling of the tertiary structure of F3H from a consensus sequence of cactus species had 88 % identity with that reported in Arabidopsis thaliana. We observed the conservation in several plant species of the  2-oxoglutarate and iron-dependent domain of F3H. This is the first report of an exploration of putative genes encoding enzymes involved in secondary metabolism in cacti species providing information that could be used to improve the production of bioactive compounds in them.   Resumen. Recientemente, ha incrementado el interés en obtener compuestos bioactivos de especies de la familia Cactaceae, que ha sido poco analizada a nivel genómico y transcriptómico. Nosotros reportamos el ensamblaje del genoma Cereus fernambucensis y analizamos además seis genomas de cactus (Carnegiea gigantea, Lophocereus schottii, Pachycereus pringlei, Pereskia humboldtii, Selenicereus undatus y Stenocereus thurberi), la anotación de genes putativos y el modelado de las estructuras tridimensionales de sus proteínas involucradas en el metabolismo de los flavonoides. Se identificaron genes que codifican proteínas relacionadas con la patogénesis vegetal (PR-10), secuencias codificantes (CDS) de aldehído reductasas y flavonoide reductasas, CDS de enzimas implicadas en la biosíntesis de compuestos fenólicos y transportadores ABC. La agrupación de las enzimas similar a la proteinasa aspártica, flavanona 3-hidroxilasa (F3H), hidroxicinamoil-CoA shikimato/quinato hidroxicinamoiltransferasa (HCT) y proteína serina/treonina-fosfatasa demostró estar altamente conservada en los genomas de los cactus analizados. Se encontró divergencia de la proteína (PEN3) de la familia transportadora de tipo ABC PDR en Cereus fernambucensis y la ausencia en esta especie de esterol metiltransferasa (SMT1). Nuestro modelado tridimensional de la estructura terciaria de F3H a partir de una secuencia consenso de especies de cactus tuvo una identidad del 88 % con la reportada en Arabidopsis thaliana. Observamos la conservación en varias especies vegetales del dominio 2-oxoglutarato y dependiente del hierro de F3H. Este es el primer informe de una exploración de genes putativos que codifican enzimas involucradas en el metabolismo secundario en especies de cactus que aporta información que podría usarse para mejorar la producción de compuestos bioactivos.