Natural immobilisation of microorganisms for continuous ethanol production

Baptista, Cristina M. S. G.; Cóias, João; Oliveira, Ana Cristina Mendes de; Oliveira, Nuno M.C.; Rocha, J. M. S.; Dempsey, Michael J.; Lannigan, Kevin C.; Benson, Paul S.

doi:10.1016/j.enzmictec.2005.12.025

Cited by 42 publications

(18 citation statements)

References 16 publications

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“…However, high volumetric productivity of the bioreactor (the biocatalyst, respectively) is not always sufficient enough for an effective process. These and former investigations on similar processes show that high productivity is in reverse correlation with the conversion rate (Baptista et al 2006). At shorter HRT, more products are converted per hour, but the product concentration is lower and it drops with the decrease of HRT (the increase of flow rate).…”

Section: Repeated Batch Production Of Ethanol By Modified Corn Stalk-mentioning

confidence: 86%

Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

Yan

Chen

et al. 2012

Appl Microbiol Biotechnol

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The aim of the present study was to examine ethanol production from concentrated food waste hydrolysates using whole cells of S. cerevisiae immobilized on corn stalks. In order to improve cell immobilization efficiency, biological modification of the carrier was carried out by cellulase hydrolysis. The results show that proper modification of the carrier with cellulase hydrolysis was suitable for cell immobilization. The mechanism proposed, cellulase hydrolysis, not only increased the immobilized cell concentration, but also disrupted the sleek surface to become rough and porous, which enhanced ethanol production. In batch fermentation with an initial reducing sugar concentration of 202.64 ± 1.86 g/l, an optimal ethanol concentration of 87.91 ± 1.98 g/l was obtained using a modified corn stalk-immobilized cell system. The ethanol concentration produced by the immobilized cells was 6.9% higher than that produced by the free cells. Ethanol production in the 14th cycle repeated batch fermentation demonstrated the enhanced stability of the immobilized yeast cells. Under continuous fermentation in an immobilized cell reactor, the maximum ethanol concentration of 84.85 g/l, and the highest ethanol yield of 0.43 g/g (of reducing sugar) were achieved at hydraulic retention time (HRT) of 3.10 h, whereas the maximum volumetric ethanol productivity of 43.54 g/l/h was observed at a HRT of 1.55 h.

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Section: Repeated Batch Production Of Ethanol By Modified Corn Stalk-mentioning

confidence: 86%

Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

Yan

Chen

et al. 2012

Appl Microbiol Biotechnol

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“…Bioethanol is mostly obtained by fermentation of sugars, which are converted into ethanol and carbon dioxide by some microorganisms; Saccharomyces cerevisiae yeasts are the most frequently used in this type of bioprocess (Dien et al 2003;Baptista et al 2006;Lin and Tanaka 2006). Another promising microorganism for the production of Electronic supplementary material The online version of this article (doi:10.1007/s11274-011-0721-7) contains supplementary material, which is available to authorized users.…”

Section: Introductionmentioning

confidence: 99%

Bioethanol production in batch mode by a native strain of Zymomonas mobilis

Pinilla

Torres

Ortiz

2011

World J Microbiol Biotechnol

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Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially, selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts, at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native strain ML1, reaching a maximum ethanol concentration of 79.78 g l -1 . ML1 and ML2 strains were identified as Z. mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l -1 , with kinetic parameters of yield of ethanol on biomass (Y P/X) = 69.01(g g -1 ), maximum volumetric productivity of ethanol (Qp max ) = 2.28 (g l -1 h -1 ), specific productivity of ethanol (q P ) = 3.54 (h -1 ) and specific growth rate (l) = 0.12 h -1 . Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman 0 s experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration of 93.55 g l -1 .

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“…The adhesion of microorganisms is inherent in immobilised cell technology with immobilised yeast systems offering considerable advantages to the fermentation industry (Kourkoutas et al 2004;Verbelen et al 2006). Immobilised yeast systems have been used in ethanolic fermentations with successful adhesion of S. cerevisiae to diverse solid carriers such as polyurethane foam (Baptista et al 2006), spent grains (Dragone et al 2008), ceramics (Demuyakor and Ohta 1992), and porous glass (Tata et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Influence of cell surface characteristics on adhesion of Saccharomyces cerevisiae to the biomaterial hydroxylapatite

White

Walker

2010

Antonie van Leeuwenhoek

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The influence of the physicochemical properties of biomaterials on microbial cell adhesion is well known, with the extent of adhesion depending on hydrophobicity, surface charge, specific functional groups and acid-base properties. Regarding yeasts, the effect of cell surfaces is often overlooked, despite the fact that generalisations may not be made between closely related strains. The current investigation compared adhesion of three industrially relevant strains of Saccharomyces cerevisiae (M-type, NCYC 1681 and ALY, strains used in production of Scotch whisky, ale and lager, respectively) to the biomaterial hydroxylapatite (HAP). Adhesion of the whisky yeast was greatest, followed by the ale strain, while adhesion of the lager strain was approximately 10-times less. According to microbial adhesion to solvents (MATS) analysis, the ale strain was hydrophobic while the whisky and lager strains were moderately hydrophilic. This contrasted with analyses of water contact angles where all strains were characterised as hydrophilic. All yeast strains were electron donating, with low electron accepting potential, as indicated by both surface energy and MATS analysis. Overall, there was a linear correlation between adhesion to HAP and the overall surface free energy of the yeasts. This is the first time that the relationship between yeast cell surface energy and adherence to a biomaterial has been described.

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Natural immobilisation of microorganisms for continuous ethanol production

Cited by 42 publications

References 16 publications

Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

Ethanol production from concentrated food waste hydrolysates with yeast cells immobilized on corn stalk

Bioethanol production in batch mode by a native strain of Zymomonas mobilis

Influence of cell surface characteristics on adhesion of Saccharomyces cerevisiae to the biomaterial hydroxylapatite

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