Biogas potential from the anaerobic digestion of banana waste (Musa Sp.) using Different bio-additives

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  • S168 Special Abstracts / Journal of Biotechnology 150S (2010) S1S576

    The best results, in terms of both triglyceride yields, wereobtained from stems. On the contrary, the growth of yeasts in thepresence of leaves was limited, probably due to the accumulationof toxic products in the medium.

    Considering dry matter yield of giant reed and lipids produc-tion rate from yeasts, the lipids production per unit of land area,ranged from 1.7 to 2.8 t ha1, and thus it was higher than thatobtainable from oil crops, such as sunower, cultivated in the samepedo-climatic conditions.



    Solar light driven H2 production with the microalga Chlamy-domonas reinhardtii in an outdoor photobioreactor

    A. Scoma1,2,, L. Giannelli 2, C. Faraloni2, G. Torzillo2

    1 Department of Applied Chemistry and Material Science (DICASM),Faculty of Engineering, University of Bologna, Italy2 Institute for the Study of the Ecosystems (ISE), National Council ofResearch (CNR), ItalyKeywords: Hydrogen; Chlamydomonas; Solar light; Tubular pho-tobioreactor

    The availability of low-cost energy within the next decades andthe ecological impact of fossil fuels exploitation have promptedconsiderable international efforts tondrenewableenergy sources.In the last years, much attention has been given to the pho-tobiological H2 production performed by the green microalgaChlamydomonas reinhardtii, particularly after Melis proposal ofthe sulfur starvation protocol (2000). Although great efforts weremade on the laboratory scale to improve photosynthetic yieldswhen providing constant articial light, low attention has beenpaid to the feasibility of the process under natural solar lightsupply. To this aim, we investigated the H2 productivity of thecommonly used strain cc124 in a 50-liter horizontal tubular pho-tobioreactor (PBR). First attempts with cultures grown in thelaboratory pointed out the photosystem 2 (PSII) underwent astrong inactivation because of both sulfur starvation and solarradiation (which may reach up to 2000mol photons m2 s1

    at the site where the PBR was operated). Thus, cultures wereacclimated to the outdoor conditions during growth, eventuallyleading to a H2 production with a culture of 20mg of chloro-phyll per liter of culture. Productivity was reduced to 21% ofthat obtained in the laboratory. Indeed, part of the culture accli-mated outdoor was tested under laboratory standard conditions,this not resulting in signicant differences on H2 productivityrespect to what previously observed (Torzillo et al., 2009). Thereduced H2 evolution outdoor was mainly due to the photoinhi-bition of the PSII (both reducing PSII remaining water splittingactivity and the initial endogenous substrates storage) and tothe consumption of energy reserves during night periods. In par-ticular, cultures tested outdoor accumulated higher amounts ofproteins, thus driving some of the reducing power out of thetypical H2 evolution pathways. Enhancements are expected byphotoprotecting the culture by means of higher chlorophyll con-centrations coupled with a better mixing, as already observed inthe laboratory (Giannelli et al., 2009). To the very best of ourknowledge, this is the rst paper in which H2 production bymeans of direct solar radiation with Chlamydomonas has beenreported.


    Melis, A., Zhang, L., et al., 2000. Plant Physiol 122, 127136.Torzillo, G., Scoma, A., et al., 2009. Int J Hyd En 34 (10), 45294536.Giannelli, L., Scoma, A., et al., 2009. Biotech Bioeng 104 (1), 7690.



    Biogas fromenergy crops: Evaluationof amulti-stageprocedure

    I. Colussi, A. Cortesi, V. Gallo, N. Stefani , R. Vitanza

    DMRN, University of Trieste, ItalyKeywords: Anaerobic digestion; Two-stage; SMA; ASBR

    An experimental method for the evaluation of a multi stageanaerobic digestion (AD) has been studied. In literature, in absenceof international standards, potential errors in the laboratory-scalequantitative evaluation of AD bioconversions, can be introduced:amongst the others, the quantication of biogas produced and thesubstrate total COD analysis,making difcult the CODbalance fromthe incoming and outgoing COD ows. To reduce the problem alaboratory-scale apparatus was assembled for the two-stage ADof two different energy crops, apples and potatoes. Two coupled5 l batch-fed completely stirred reactors, one for the hydrolytic-acidogenic step and one for the acetogenic-methanogenic step,kept at mesophilic temperature (35 C), were adopted. In the rstacidogenic reactor, the inuence of fermentative bacteria (Sac-charomyces cerevisiae) on the degree of idrolization and on theacidication rate of the vegetable substrates was measured takinginto account the carbon dioxide production, the total and solubleCOD ratio and thepHvariations. Using fermentative bacteria, a highidrolization degree and a stable lowpHwas reachedwith apple andpotato substrates: all runs were performed without the addition ofchemicals. Samples of idrolized substrates were sent to the secondmethanogenic bioreactor to evaluate the specic gas production(SGP), the methane yield in the biogas produced and the specicmethanogenic activity (SMA).The whole process was repeated forsimulating an anaerobic sequencing batch reactor (ASBR) processand nal COD balances were carried on to verify experiments reli-ability.



    Biogas potential from the anaerobic digestion of banana waste(Musa Sp.) using Different bio-additives

    Nelson Caballero-Arzpalo1,, Carmen Ponce-Caballero1, CinthiaC. Gamboa-Loira1, Roland Meyer-Pittroff 2

    1 Universidad Autnoma de Yucatn, Mexico2 Technische Universitaet Muenchen, GermanyKeywords: Biogas; Anaerobic digestion; Banana waste; Enzimesand microorganisms

    AbstractThe banana producers in the southeast region ofMexico experi-

    ence damage or decomposition of their product along the differentstages of the production process. This generates non commercialmaterial which is currently disposed incorrectly on the soil causingpollution problems which could increase the risks to the humanand environmental health. Additionally, these wastes represent aloss of organic material which could be reused as a bio-energeticsource contributing in such way to reduce the contamination. Sim-

  • Special Abstracts / Journal of Biotechnology 150S (2010) S1S576 S169

    ilar problems could be found in other banana-producing countries.Several studies have been done about the biogas production basedon fruit residues. Nevertheless, only few of them correlate theorganic substrate concentration and the nutrient content with thebiogas yield produced under different bio-additives inuences.

    Therefore, the objective of this research work was to evaluatethe biogas potential of banana waste in micro-scale reactors underthermophilic conditions (55 C) using several bio-additives aloneor combined. For this purpose, local banana (Musa sp.) in a concen-tration of 6 g of volatile total solids by liter (VTS/L) and differentbio-additives were used. The laboratory analysis and the digestionprocedure were conducted according to standard methods.

    Means univariate and multivariate statistical analysis wasdetermined which of the used bio-additives have signicant inu-ence on the potential for biogas production from banana waste.



    High-throughput sequencing approach provides insight into anovel route to new biofuel bioreactors

    . Tri1, T. Kupai1,, G. Marti2, I. Nagy3, B. Gr1, B. Uzonyi1

    1 DEKUT R&D Non-Prot Organization, Hungary2 Institute for Plant Genomics, Human Biotechnology and Bioenergy,Zoltn Bay Foundation for Applied Research, Hungary3 SeqOmics Biotechnology Ltd., HungaryKeywords: Cellulase enzyme; Metagenomic; Bioalcohol

    The oil prices are constantly rising and with forecasts of theapproaching run out of oil supplies, there is a demanding need toreduce the dependency from petroleum. Hence, a quest for moreefcient methods of generating biofuel has been recently boosted.Accordingly, ourobjective is to improve theenzymatichydrolysis ofcellulosic biomass (e.g. cornorwheat straw) so that it canbeusedasprimary material for bioalcohol production. Thus, a metagenomicapproach has been applied, in order to identify novel cellulases thatcan be utilized for turning plants into combustible fuel sources.

    For this, samples were collected from bovine rumen and silage,anaerobicmilieus where cellulose hydrolysis is intensive and com-plete cellulose degradation occurs due to the microora. DNAisolation was performed directly from the environmental sam-ples and used for metagenomic DNA library preparation. Clonesuniquely representing the DNA of the microora were sequencedwith ABI SOLiD V3 Plus System which resulted in 70 millionreads. The gained data was processed with in-house developedalgorithms seeking for sequences encoding potentially efcientcellulases. Selection of putative cellulases was done by screen-ing the aligned sequences primarily for homology with knowncellulase sequences and enzyme-specic domains. Following thesequence-related structure, function and stability prediction, theclones containing the pinpointed cellulase genes were picked. Thetwo most promising cellulase genes were selected and built in anexpression strain. After purication, the produced enzymes weretested for substrate specicity and enzymeactivity.

    Biochemical analysis of cellulase function proved that ourmetagenomic approach using the sequence-based screening isapplicable for identifying new enzymes. Our ndings show thatthe high-throughput sequencing approach can lead to the identi-cation of novel cellulase enzymes.



    Continuous ethanol fermentation using immobilized yeast

    Q.D. Nguyen , G. Gurin, . Hoschke

    Corvinus University of Budapest, HungaryKeywords: Biofuel; Immobilized cells; Ethanol; Continuous process

    Introduction: Brewing, distilling and biofuel industries are eco-nomically powerful and thus have always been in the forefrontof technological development. The use of an immobilized yeastcell system for alcoholic fermentation is an attractive and rapidlyexpanding research area because of the additional technical andeconomical advantages compared to the use of traditional batchprocess with free cells including rapid processing and high volu-metric productivity as well as low capital and production costs.The aim of this study was to evaluate the continuous ethanol fer-mentation system applying immobilized yeast.

    Methods: Adsorption method was applied for immobilizationof yeast cells on SIKUG glass porous carriers. Carbohydrates andalcohols were analysed using HPLC technique.

    Results: According to scanning microscopic pictures and drop-ping of cell concentration, all tested yeast strains were ableto immobilize onto surface of carriers. Laboratory packed-bedbioreactor with 1L working volume was design and created. Theproduction of ethanolwas steady after 24hours of operation. Biore-actor was able to operate up to 250g/L concentration substrate. Inthe case of glucose substrate (product of starch hydrolysis), opti-mal ow rate and substrate concentrationwere found to be 32ml/hand 180g/L, respectively. The productivity of ethanolwas 78g/L for180g/L glucose substrate. In the case of Jerusalem artichoke sub-strate, maximal ethanol conversion was 99% at ow rate 55ml/h.The productivity of ethanol was 64g/L and 61g/L for 135g/L and125g/L at ow rate 60ml/h, respectively. Bioreactor was stablemore than 3 months under operation at 30 oC.

    Discussion: SIKUG carriers are capable to immobilise yeast cellsonto surface that can be applied to design packed-bed bioreactorfor modelling continuous alcohol fermentation system. Applyingthis system the technological time of primary fermentation processcan be shortened, thus increase the productivity of ethanol. Thismodel can be used to scale up to a larger scale packed-bed columnbioreactor for production of bioethanol.

    Acknowledgements: This work was supported by National Ofcefor Research and Technology through project acronym PALINKAHand Bolyai Research Grant from Hungarian Academy of Sciences.



    Cellulase production by semi-continuous solid state fermenta-tion (SSF)

    Yujie Zhou1,, Jianan Zhang1, Lingmei Dai1, Tiegang Hu2, DehuaLiu1, Yonggang Wang2

    1 Tsinghua University, China2 China University of Mining and Technology, ChinaKeywords: Cellulase; Solid state fermentation; Semi-continuous

    SSFcouldoffer someapparenteconomicandengineeringadvan-tages over the submerged fermentation (SmF), which includehigher concentration of products, lower cost, less waste outputand so on. SSF processes are usually operated in batch mode, andthe disadvantages of this mode are the requirement for regular re-inoculation and the low productivity in repeated batch operation.In this study, two kinds of semi-continuous SSF processes were


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