Effect of matching microalgal strains origin and regional weather condition on biomass productivity in environmental photobioreactors

It is generally assumed that increased microalgal biomass productivity on any particular geographical site would be most likely achieved by strains native to that region. However, direct assessment of that hypothesis remains challenging. Here we isolated and biochemically characterized twenty-six microalgal strains from one of the regions with the highest irradiances of the planet. Biomass and lipids productivity of phylogenetically-close Scenedesmus strains native to regions of contrasting irradiances performed similarly under laboratory culture conditions. Culture simulations in environmental photobioreactors, mimicking regional weather conditions, broadly showed physiological responses of these strains according to their origin. However, under the mean weather conditions of a predicted highly productive region, an exotic strain from a lower irradiance zone resulted 40% more productive than a phylogenetically close-relative native strain. These results challenge the generalized view of the convenience of using native microalgae to increase productivity and broadens the discussion towards alternative scenarios.Fil: Coronel, Camila Denise. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Do Nascimento, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

Sucrose is involved in diazotrophic metabolism of the heterocyst-forming cyanobacterium Anabaena sp

Sucrose synthase (SuS) expression was studied in the filamentous, nitrogen-fixing cyanobacterium Anabaena sp. PCC 7119. SuS activity, SusA polypeptide, and susA mRNA levels were lower in cells cultured diazotrophically than in the presence of combined nitrogen. An insertional susA mutant presented a dramatic increase in sucrose levels, whereas the disaccharide was not detectable in a susA overexpressing strain, indicating that SusA is involved in the cleavage of sucrose in vivo. Diazotrophic growth was impaired in the susA overexpressing strain, suggesting a role for sucrose in diazotrophic metabolism and the involvement of SusA in the control of carbon flux in the N2-fixing filament.Fil: Curatti, Leonardo. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Flores, Enrique. Universidad de Sevilla; EspañaFil: Salerno, Graciela Lidia. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sucrose metabolism: Anabaena sucrose-phosphate synthase and sucrose-phosphate phosphatase define minimal functional domains shuffled during evolution

Based on the functional characterization of sucrose biosynthesis related proteins [SBP: sucrose-phosphate synthase (SPS), sucrose-phosphate phosphatase (SPP), and sucrose synthase (SuS)] in Anabaena sp. PCC7120 and sequence analysis, we have shown that SBP are restricted to cyanobacterium species and plants, and that they are multidomain proteins with modular architecture. Anabaena SPS, a minimal catalytic SPS unit, defines a glucosyltransferase domain present in all SPSs and SuSs. Similarly, Anabaena SPP defines a phosphohydrolase domain characteristic of all SPPs and some SPSs. Phylogenetic analysis points towards the evolution of modern cyanobacterial and plant SBP from a bidomainal common ancestral SPS-like gene.Fil: Cumino, Andrea Carina. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Curatti, Leonardo. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giarrocco, Laura Estela. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Salerno, Graciela Lidia. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sucrose-to-ethanol microalgae-based platform using seawater

Microalgal biomass is increasingly considered a promising feedstock for the production of bioethanol because it has simpler biochemical composition and structural features than plant feedstocks. However, it still requires hazardous and/or expensive acid or enzymatic saccharification processes before its conversion into ethanol by fermentation. To bypass this limitation, we identified microalgal strains that accumulate up to 10% (w/w) of sucrose, a readily fermentable sugar. Conditions were optimized to produce sucrose in half-strength seawater, as well as efficient extraction by very mild procedures, and conversion into ethanol. We present a model based on cultivation in environmental photobioreactors that predicted a productivity of 4,200 L ethanol · ha-1 · year-1 in raceway ponds in Brazil, approaching the average sucrose and ethanol productivity from sugarcane.Fil: Sanz Smachetti, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Coronel, Camila Denise. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Salerno, Graciela Lidia. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

NifB and NifEN protein levels are regulated by ClpX2 under nitrogen fixation conditions in Azotobacter vinelandii

The major part of biological nitrogen fixation is catalysed by the molybdenum nitrogenase that carries at its active site the iron and molybdenum cofactor (FeMo-co). The nitrogen fixation (nif) genes required for the biosynthesis of FeMo-co are derepressed in the absence of a source of fixed nitrogen. The nifB gene product is remarkable because it assembles NifB-co, a complex cluster proposed to comprise a [6Fe-9S-X] cluster, from simpler [Fe-S] clusters common to other metabolic pathways. NifB-co is a common intermediate of the biosyntheses of the cofactors present in the molybdenum, vanadium and iron nitrogenases. In this work, the expression of the Azotobacter vinelandii nifB gene was uncoupled from its natural nif regulation to show that NifB protein levels are lower in cells growing diazotrophically than in cells growing at the expense of ammonium. A. vinelandii carries a duplicated copy of the ATPase component of the ubiquitous ClpXP protease (ClpX2), which is induced under nitrogen fixing conditions. Inactivation of clpX2 resulted in the accumulation of NifB and NifEN and a defect in diazotrophic growth, especially when iron was in short supply. Mutations in nifE, nifN and nifX or in nifA also affected NifB accumulation, suggesting that NifB susceptibility to degradation might vary during its catalytic cycle.Fil: Martínez Noël, Giselle María Astrid. Centro de Biotecnología y Genómica de Plantas; EspañaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; ArgentinaFil: Hernandez, Jose A.. Midwestern University; Estados UnidosFil: Rubio, Luis M.. Centro de Biotecnología y Genómica de Plantas; Españ

Association with an ammonium-excreting bacterium allows diazotrophic culture of oil-rich eukaryotic microalgae

Concerns regarding the depletion of the world's reserves of oil and global climate change have promoted an intensification of research and development toward the production of biofuels and other alternative sources of energy during the last years. There is currently much interest in developing the technology for third-generation biofuels from microalgal biomass mainly because of its potential for high yields and reduced land use changes in comparison with biofuels derived from plant feedstocks. Regardless of the nature of the feedstock, the use of fertilizers, especially nitrogen, entails a potential economic and environmental drawback for the sustainability of biofuel production. In this work, we have studied the possibility of nitrogen biofertilization by diazotrophic bacteria applied to cultured microalgae as a promising feedstock for next-generation biofuels. We have obtained an Azotobacter vinelandii mutant strain that accumulates several times more ammonium in culture medium than wild-type cells. The ammonium excreted by the mutant cells is bioavailable to promote the growth of nondiazotrophic microalgae. Moreover, this synthetic symbiosis was able to produce an oil-rich microalgal biomass using both carbon and nitrogen from the air. This work provides a proof of concept that artificial symbiosis may be considered an alternative strategy for the low-N-intensive cultivation of microalgae for the sustainable production of next-generation biofuels and other bioproducts.Fil: Ortiz Marquez, Juan César Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Do Nascimento, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Dublan, María de Los Ángeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

Ethanol and protein production from minimally processed biomass of a genetically-modified cyanobacterium over-accumulating sucrose

One of the main bottlenecks of a microalgal or cyanobacterial biomass biorefinery is the separation of differentuseful fractions using simple, low energy-consuming, cost-effective, and scalable separation processes. Althoughthe carbohydrates-rich biomass of these microorganisms presents clear advantages over conventional terrestrialcrops as feedstocks for ethanol, it still requires acid and/or enzymatic hydrolysis for efficient fermentation. Here,we show the genetic modification of carbohydrates partitioning in afilamentous cyanobacterium towards theaccumulation of sucrose up to 10% (w/w) as a readily fermentable feedstock. We optimized two methods for thepreparation of concentrated sucrose syrups, which were efficiently converted into ethanol by yeasts, without theneed of additional pretreatments. Biomass drying and milling, followed by aqueous extraction of sugars andproteins, and the recovery of proteins by short pulses of heat, kept the value of sugars as a feedstock for ethanoland protein for feed supplements within a cost-effective biomass biorefinery.Fil: Sanz Smachetti, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Perez Cenci, Macarena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Salerno, Graciela Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentina. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

Bioprospecting for fast growing and biomass characterization of oleaginous microalgae from South-Eastern Buenos Aires, Argentina

As part of pioneering efforts to assess the potential of native microalgae as biofuel feedstock in South–Eastern Buenos Aires, 34 monoalgal cultures (corresponding to the Phylum Chlorophyta) were established and 21 were selected for further growth and biomass composition characterization. Novel RNA sequences in the ITS1-5.8S-ITS2 region were identified. Some strains showed desirable traits as biodiesel feedstock such as (i) apparent maximal doubling times of 6 h, (ii) lipids accumulation of up to 43% of their dry biomass, (iii) high ration of mono-unsaturated to poly-unsaturated fatty acids, (iv) high response to CO2 supplementation, and (v) complete sedimentation in 4 h. Data of the outdoors performance of some strains suggested they might represent valuable resources for future research towards the regional development of the technology for microalgae-based biofuels.Fil: Do Nascimento, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Ortiz Marquez, Juan César Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Sánchez Rizza, Lara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Echarte, Maria Mercedes. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

A semi-closed loop microalgal biomass production-platform for ethanol from renewable sources of nitrogen and phosphorous

Production of microalgal biomass for feed and fuels demands unsustainable large amounts of fertilizers. The most broadly considered alternative sources of nutrients/fertilizer for microalgae are wastewater and internal recycling in closed-loop production platforms. However, these strategies largely disable co-production of feed and fuel in biomass biorefineries for an increased economic and environmental feasibility. In this study, we aimed at providing proof-of-concept for a semi-closed loop microalgal production-platform and biomass biorefinery for ethanol and feed from renewable resources of N and P. Atmospheric N 2 was assimilated into a N 2 -fixing cyanobacterial biomass, which sustained growth of a microalga that accumulated high levels of carbohydrates (up to 60% (w/w)) as a sole source of fertilizer. The microalgal biomass was efficiently saccharified with H 2 SO 4 , which was recycled to release soluble PO 4 3- from bone meal as a renewable source of P. Fermenting these P-enriched preparations with yeasts quantitatively produced ethanol at theoretical yields, a concentration of up to 50 g ethanol. L −1 and a yield of 0.25 g ethanol. g biomass −1 . Calculations suggested a potential yield from 7600 to 10,800 L ethanol. ha −1 . year −1 , under Buenos Aires environmental conditions, which would be higher than that currently obtained from maize feedstocks. The residual fermentation vinasse, supplemented with P and containing other downstream-process reagents, was recycled as a sole source of macronutrients for the cultivation of the N 2 -fixing cyanobacterium to close the production cycle. Water recycling and co-production of residual biomass enriched in fat and protein as potential feed are also shown. This semi-closed loop biomass production-platform reconciles the concepts of microalgal biomass biorefineries for the co-production of feedstocks for biofuels and feed and nutrients recycling in closed-loop systems that largely minimizes production of waste.Fil: Sánchez Rizza, Lara. Fundación para Investigaciones Biológicas Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Coronel, Camila Denise. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Sanz Smachetti, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Do Nascimento, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentina. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

Plant-adapted Escherichia coli show increased lettuce colonizing ability, resistance to oxidative stress and chemotactic response

Background: Escherichia coli is a widespread gut commensal and often a versatile pathogen of public health concern. E. coli are also frequently found in different environments and/or alternative secondary hosts, such as plant tissues. The lifestyle of E. coli in plants is poorly understood and has potential implications for food safety. Methods/Principal Findings: This work shows that a human commensal strain of E. coli K12 readily colonizes lettuce seedlings and produces large microcolony-like cell aggregates in leaves, especially in young leaves, in proximity to the vascular tissue. Our observations strongly suggest that those cell aggregates arise from multiplication of single bacterial cells that reach those spots. We showed that E. coli isolated from colonized leaves progressively colonize lettuce seedlings to higher titers, suggesting a fast adaptation process. E. coli cells isolated from leaves presented a dramatic rise in tolerance to oxidative stress and became more chemotactic responsive towards lettuce leaf extracts. Mutant strains impaired in their chemotactic response were less efficient lettuce colonizers than the chemotactic isogenic strain. However, acclimation to oxidative stress and/or minimal medium alone failed to prime E. coli cells for enhanced lettuce colonization efficiency. Conclusion/Significance: These findings help to understand the physiological adaptation during the alternative lifestyle of E. coli in/on plant tissues.Fil: Dublan, María de Los Ángeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; ArgentinaFil: Ortiz Marquez, Juan César Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; Argentina. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Lett, Lina Analía Carola. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Curatti, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones En Biodiversidad y Biotecnología; Argentina. Fundación para Investigaciones Biológicas Aplicadas; Argentin