Eberto Novelo

Carbon dioxide fixation and lipid storage by Scenedesmus obtusiusculus

An indigenous microalga was isolated from the springs in Cuatro Ciénegas, México. It was morphologically identified as Scenedesmus obtusiusculus and cultivated in bubble-column photobioreactors in batch operation mode. This microalga grows at 10% of carbon dioxide (CO(2)) showing a maximum CO(2) fixation rate of 970gm(-3)d(-1). The microalga, without any nutrient limitation, contained 20% of nonpolar lipids with a biomass productivity of 500gm(-3)d(-1) and a maximum biomass concentration of around 6,000gm(-3) at 5% CO(2) and irradiance of 134μmolm(-2)s(-1). Furthermore, it was observed that the microalga stored 55.7% of nonpolar lipids when 5% CO(2) was fed at 0.8vvm and 54.7μmolm(-2)s(-1) under nitrogen starvation. The lipid profile included C16:0, C18:0, C18:1n9t, C18:1n9c, C18:3n6 with a productivity of 200g lipid m(-3)d(-1). Therefore, the microalga may have biotechnological potential producing lipids for biodiesel.

Changes of phytoplankton communities in Lakes Naivasha and Oloidien, examples of degradation and salinization of lakes in the Kenyan Rift Valley

Increasing degradation of the water quality, caused by overuse and salinization, leads to considerable changes of the phytoplankton composition in Kenyan Rift Valley lakes. Exemplarily, the phytoplankton communities and biomasses of deteriorating freshwater Lake Naivasha and salinizing Lake Oloidien were studied between 2001 and 2005, accompanied by physico-chemical measurements (pH, total phosphorus and nitrogen, alkalinity, conductivity). Over the last three decades, the ecology of these two water basins has been subjected to dramatic changes, caused by excessive use of water and catchment area by man. In L. Naivasha a shift in the dominance of coccoid cyanobacteria towards dominance of Chlorophyceae (Botryococcus terribilis) was observed. Lake Oloidien exhibited a shift in the dominance of coccoid Chlorophyceae towards dominance of cyanobacteria (Arthrospira fusiformis, Anabaenopsis elenkinii). Phytoplankton findings and chemical data demonstrate that L. Naivasha has developed towards a eutrophic freshwater lake while L. Oloidien has progressed towards a hypereutrophic alkaline-saline lake.

Phylogenetic relationship and divergence among planktonic strains of Arthrospira (Oscillatoriales, Cyanobacteria) of African, Asian and American origin deduced by 16S-23S ITS and phycocyanin operon sequences

Dadheech P.K., Ballot A., Casper P., Kotut K., Novelo E., Lemma B., Pröschold T. and Krienitz L. 2010. Phylogenetic relationship and divergence among planktonic strains of Arthrospira (Oscillatoriales, Cyanobacteria) of African, Asian and American origin deduced by 16S–23S ITS and phycocyanin operon sequences. Phycologia 49: 361–372. DOI: 10.2216/09-71.1 Arthrospira comprises multicellular, cylindrical, usually screwlike coiled trichomes and is cultivated commercially. In this study, 33 new strains of Arthrospira isolated from plankton samples collected in Mexico, East Africa and India were investigated and compared with 53 strains or samples of earlier considerations. The study included observations of morphological features and molecular phylogenetic analyses on the basis of nucleotide sequences of internal transcribed spacer (ITS) between 16S rRNA and 23S rRNA genes and partial sequences of beta and alpha subunits including intergenic spacer (cpcBA-IGS) of phycocyanin operon. Morphological traits of Arthrospira such as trichome width, type of coiling and apical cell were not always consistent in culture conditions. It was revealed that Arthrospira phylogeny on the basis of cpcBA-IGS locus was broadly comparable with the ITS region as both phylogenetic trees derived from nucleotide sequences could be divided into two main clusters. Cluster I comprised sequences from American strains mainly, whereas cluster II contained the sequences of the strains originating from Africa and Asia chiefly. Both genetic regions of the strains investigated in the present study coincidently showed a significant sequence divergence among Arthrospira strains from East Africa, India and Mexico indicating possible distinct evolutionary lineages.

Population dynamics in mixed cultures of Neochloris oleoabundans and native microalgae from water of a polluted river and isolation of a diatom consortium for the production of lipid rich biomass.

The production of biodiesel utilizing microalgae has driven innovation worldwide, especially trying to overcome the current economic and technological limitations of the whole process. Within these efforts, the use of wastewater to cultivate oleaginous microalgae or the use of dual-purpose microalgae-bacteria-based systems that treat wastewater and produce oleaginous microalgae have become an attractive alternative. The aim of this work was to evaluate the population dynamics which occurred in mixed cultures of Neochloris oleoabundans with other native microalgae, in mixtures of a synthetic medium (BBM) and water of an urban polluted river. The effect of temperature, nutrient availability and the microscopic monitoring of the population dynamics in such mixed cultures were carried out. Furthermore, the isolation of the predominant consortium of diatoms and the evaluation of its kinetics of growth and its capacity for removal of pollutants was also performed. Results indicated that such green microalgae only predominated in mixtures containing 80% or 60% of the synthetic medium. In mixtures containing a volume of the polluted river higher than 40%, other microalgae predominated, especially diatoms of various genera. The diatom consortium isolated from a 100% of the rivers water sampled in spring (April), was formed mainly by a population of Nitzchia frustulum and in less extent of Navicula sp. It showed a significantly higher specific growth rate when cultivated in water from the river, compared to cultures in synthetic modified diatom medium (MDM) and at 32°C, compared to cultures incubated at 25°C. The consortium was able to remove 95.45% and 95.78% of ammonia nitrogen, 60% and 62.5% of nitrates at 32°C and 25°C, respectively, after 2 days. It also removed 95% of phosphates at 32°C and 67% at 25°C after 4 days from the polluted river. Diatoms also showed significant accumulation of lipids after 10 days of cultivation when stained with Sudan III. In conclusion, such diatom consortium showed a large potential for being used in a dual-purpose system that could treat the water from polluted streams and that could produce lipid rich biomass.

Las microaLgas de Tillandsia multicaulis steud. (BromeLiaceae) de La reserva ecoLógica "La martinica", veracruz

Bromeliads have the ability to retain water in the leaf axils that are known as tanks or phytotelmata; they support complex food webs with all types of organisms from bacteria to small vertebrates. In this paper, we present the first approach to the microalgae living in the tanks of a species of bromeliad at “La Martinica” Ecological Reserve, in Banderilla, Veracruz. The collections were studied in preserved material and cultures. About 60 algae were obtained, belonging to Cyanoprokariota, Euglenophyta, Cryptophyta, Chlorophyta and Bacillariophyta, but only 16 species have been identified. We conclude Tillandsia multicaulis tanks provide suitable conditions for the development of microalgae and the location and morphology of the bromeliad influence the distribution of this biological group. The shortage of individuals did not allow a more precise identification. In the cultures, we could detect species not seen in the preserved material, indicating a much richer flora than the one we could observe directly.