Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576 S165

[P-B.74]

Challenging metabolic engineering concepts to industrial con-ditions: The modifications in redox metabolism of S. cerevisiaefor bioethanol

E.V.S. Pereira, R.S.G. dos Anjos, A.C.M. Basilio, F.C.B. Leite, M.A.Morais ∗, D.A. Simoes

Federal University of Pernambuco, BrazilKeywords: Bioethanol; Metabolic engineering; Fermentation;Redox metabolism

The increasing demand for bioethanol worldwide induces manyefforts for increasing its production, and the metabolic engineer-ing of yeast cells is one alternative for increasing fermentationyield. At industrial conditions, ethanol yield is in the range of 90%of the maximal due to side production of glycerol, biomass andsmall amounts of organic acids. Thus, metabolic engineering strate-gies have been focus on the decrease of glycerol, the major batchfermentation by-product, in order to increase ethanol production.Recombinant strains of S. cerevisiae cells for different metabolicengineering strategies were submitted to fermentation assays indifferent medium carbon/nitrogen ratio, using high biomass andoxygen limitation. Three strategies were tested. The first wasbased on the modification of ammonia assimilation by changingthe NADPH-dependent GDH1 pathway by ATP-consuming NADH-dependent GS-GOGAT pathway (Nissen et al 2000). The secondstrategy attempt to by-pass the yeast NAD-dependent glutaralde-hyde 3-P dehydrogenase by a bacterial NADP-dependent enzymeexpressing the gapN gene (Bro et al, 2006). And in the thirdstrategy, yeast cells expressed the bacterial gene encoding NAD-dependent alanine dehydrogenase. Both laboratory and industrialstrains were modified. The results corroborated the publishedmetabolic effect under laboratory medium composition. However,when the substrate was changed to composition closer to thosefound in industrial sugar cane juice the genetic modifications hardlyproduced the expected effect on ethanol yield. Only cells with lowergrowth rates (over-expressing gapN or deleted for gdh1) producedsignificantly more ethanol and less glycerol than their parental.However, as we already know, such low growing cell might not bestable under hard environmental conditions (Silva-Filho et al 2005).Another important question to be raised is the fact that industrialstrains are already much close to maximal theoretical yield, so thatmeasuring small changes at high cell density and high sugar contentcan be a difficult task.

doi:10.1016/j.jbiotec.2010.08.427

[P-B.75]

Optimization of biogas production with bioconversion oforganic solid wastes (manure) and food industry wastes

S. Curcio ∗, V. Calabro’, M. Aversa, E. Ricca, S. Sansonetti, G. Iorio

University of Calabria - Department of Engineering Modeling - RENDE(CS), ItalyKeywords: Biogas; Anaerobic digestion; Modeling; Optimization

The production of biogas from organic solid waste representsa challenge for the production of energy from biomass. Biogasrepresents an example of fuel gas obtained by biomass anaerobicfermentation of manure, sewage sludge, biodegradable wastes andmunicipal wastes.

Due the amount of waste, biogas production represents a verypromising way to solve the problem of waste treatment thanksto the production of bio-energy, as thermal as electric. Further-

more, the solid residuals of fermentation might be reused asfertilizers.

Aim of this paper was the optimization of biogas production in apilot-scale fermentor where mixture of solid organic and vegetableresiduals are tested.

Different food waste have been used as co-substrate, such asolive mills wastes (namely wastewaters and husks), orange juiceproduction residuals (like peels, also named “pastazzo”), cheesewhey, potato residuals.

The amount of biogas and its composition have been related tothe operating parameters of temperature, mixing rate and condi-tions, organic solids and vegetable residuals feed mass ratio.

Experimental results obtained at both laboratory and pilot scalepermitted to estimate the optimal feed composition in order tomaximise the biogas production.

A fluid-dynamic study has been carried out to optimize the stir-ring operating conditions, coupling experimental and theoreticalanalysis.

A mathematical model has been also formulated in order topredict optimal biogas production and composition as function ofoperative parameters. Based on model results, the process scale-uphas been done and a process control system has been also designed.

A specific attention has been also dedicated to the use of biogas,in co-generation system in order to produce thermal and electricalenergy, and in the cited use of sub-products as fertilizer and in therecovery of water. This information has been used to carry out aneconomic analysis of the whole process.

doi:10.1016/j.jbiotec.2010.08.428

[P-B.76]

Potentiality of Cynara cardunculus L. as energy crop

E. Portis 1,∗, A. Acquadro 1, A.M.G. Longo 2, R. Mauro 2, G.Mauromicale 2, S. Lanteri 1

1 DIVAPRA Plant Genetics and Breeding, University of Torino, Italy2 DACPA Scienze Agronomiche, University of Catania, ItalyKeywords: Cynara cardunculus L.; Energy crop; Biomass and oil;Molecular linkage map

The Asteraceae (Compositae) species Cynara cardunculus L. isnative to the Mediterranean basin, and incorporates the taxa globeartichoke (var. scolymus), cultivated cardoon (var. altilis) and theirancestor wild cardoon (var. sylvestris). The three forms are fullycross-compatible with one another and produce fertile inter-taxonF1 hybrids.

Previous studies demonstrate that both cultivated and wildforms of C. cardunculus can be exploited for oil and biomass produc-tion. Up to 2 t/ha/year of seeds can be produced, their oil contentfluctuates from 25% to 33%, has a composition comparable to theone of sunflower and safflower seeds and is suitable for biodieselproduction. The species is also exploitable for the production of lig-nocellulosic biomass for energy or paper pulp, as the biomass yieldis up to 19.0 t/ha dry matter with a moisture content from 10% to15%.

Within the Italian Project ‘CYNERGIA’, funded by the ItalianMIPAAF (Ministero delle politiche agricole alimentari e forestali),we have identified genotypes of both wild and cultivated car-doon characterized by high seed and/or biomass production, whichare currently assessed in different environments under low-inputfarming techniques.

Recently we have applied the double pseudo-testcross map-ping strategy to construct molecular linkage maps based on the F1progeny of a cross between a clone of globe artichoke ‘RomanescoC3′ and a genotype of cultivated cardoon, using mainly AFLPs and