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Biohydrogen production from arabinose and glucose using extreme thermophilic anaerobic mixed cultures.

Abreu AA, Karakashev D, Angelidaki I, Sousa DZ, Alves MM - Biotechnol Biofuels (2012)

Bottom Line: Denaturing gradient gel electrophoresis (DGGE) results revealed no significant difference on the bacterial community composition between operational periods and between the reactors.Continuous hydrogen production rate from arabinose was significantly higher than from glucose, when higher organic loading rate was used.The effect of hydrogen partial pressure on hydrogen production from glucose in batch mode was related to the extent of sugar utilization and not to the efficiency of substrate conversion to hydrogen.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal. madalena.alves@deb.uminho.pt.

ABSTRACT

Background: Second generation hydrogen fermentation technologies using organic agricultural and forestry wastes are emerging. The efficient microbial fermentation of hexoses and pentoses resulting from the pretreatment of lingocellulosic materials is essential for the success of these processes.

Results: Conversion of arabinose and glucose to hydrogen, by extreme thermophilic, anaerobic, mixed cultures was studied in continuous (70°C, pH 5.5) and batch (70°C, pH 5.5 and pH 7) assays. Two expanded granular sludge bed (EGSB) reactors, Rarab and Rgluc, were continuously fed with arabinose and glucose, respectively. No significant differences in reactor performance were observed for arabinose and glucose organic loading rates (OLR) ranging from 4.3 to 7.1 kgCOD m-3 d-1. However, for an OLR of 14.2 kgCOD m-3 d-1, hydrogen production rate and hydrogen yield were higher in Rarab than in Rgluc (average hydrogen production rate of 3.2 and 2.0 LH2 L-1 d-1 and hydrogen yield of 1.10 and 0.75 molH2 mol-1substrate for Rarab and Rgluc, respectively). Lower hydrogen production in Rgluc was associated with higher lactate production. Denaturing gradient gel electrophoresis (DGGE) results revealed no significant difference on the bacterial community composition between operational periods and between the reactors. Increased hydrogen production was observed in batch experiments when hydrogen partial pressure was kept low, both with arabinose and glucose as substrate. Sugars were completely consumed and hydrogen production stimulated (62% higher) when pH 7 was used instead of pH 5.5.

Conclusions: Continuous hydrogen production rate from arabinose was significantly higher than from glucose, when higher organic loading rate was used. The effect of hydrogen partial pressure on hydrogen production from glucose in batch mode was related to the extent of sugar utilization and not to the efficiency of substrate conversion to hydrogen. Furthermore, at pH 7.0, sugars uptake, hydrogen production and yield were higher than at pH 5.5, with both arabinose and glucose as substrates.

No MeSH data available.


DGGE profile of granular sludge samples from a reactor fed with arabinose and glucose [6]and at Day 27 and Day 41 from arabinose (and glucose reactors.
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Figure 4: DGGE profile of granular sludge samples from a reactor fed with arabinose and glucose [6]and at Day 27 and Day 41 from arabinose (and glucose reactors.

Mentions: DGGE profiles generated for sludge samples withdrawn from Rarab and Rgluc (Figure 4) show that bacterial composition in both reactors' sludge at the end of periods II (Day 27) and III (Day 41) are identical. Differences in substrate composition did not affect the bacterial community in reactors Rarab and Rgluc and similarity index between Arab/Gluc samples at the end of the operation was as high as 94%. Predominant DGGE bands in Rgluc and Rarab were identical to the ones present in the inoculum used in this study and for which the phylogeny had been previously assessed [6]. Two of the predominant DGGE bands showed high similarity (> 99%) with the hydrogen-producing Thermoanaerobacterium thermosaccharolyticum. Members of the Klebsiella, Bacillus and Sporolactobacillus genera, detected in the inoculum sludge, were also predominant in Rgluc and Rarab.


Biohydrogen production from arabinose and glucose using extreme thermophilic anaerobic mixed cultures.

Abreu AA, Karakashev D, Angelidaki I, Sousa DZ, Alves MM - Biotechnol Biofuels (2012)

DGGE profile of granular sludge samples from a reactor fed with arabinose and glucose [6]and at Day 27 and Day 41 from arabinose (and glucose reactors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298801&req=5

Figure 4: DGGE profile of granular sludge samples from a reactor fed with arabinose and glucose [6]and at Day 27 and Day 41 from arabinose (and glucose reactors.
Mentions: DGGE profiles generated for sludge samples withdrawn from Rarab and Rgluc (Figure 4) show that bacterial composition in both reactors' sludge at the end of periods II (Day 27) and III (Day 41) are identical. Differences in substrate composition did not affect the bacterial community in reactors Rarab and Rgluc and similarity index between Arab/Gluc samples at the end of the operation was as high as 94%. Predominant DGGE bands in Rgluc and Rarab were identical to the ones present in the inoculum used in this study and for which the phylogeny had been previously assessed [6]. Two of the predominant DGGE bands showed high similarity (> 99%) with the hydrogen-producing Thermoanaerobacterium thermosaccharolyticum. Members of the Klebsiella, Bacillus and Sporolactobacillus genera, detected in the inoculum sludge, were also predominant in Rgluc and Rarab.

Bottom Line: Denaturing gradient gel electrophoresis (DGGE) results revealed no significant difference on the bacterial community composition between operational periods and between the reactors.Continuous hydrogen production rate from arabinose was significantly higher than from glucose, when higher organic loading rate was used.The effect of hydrogen partial pressure on hydrogen production from glucose in batch mode was related to the extent of sugar utilization and not to the efficiency of substrate conversion to hydrogen.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal. madalena.alves@deb.uminho.pt.

ABSTRACT

Background: Second generation hydrogen fermentation technologies using organic agricultural and forestry wastes are emerging. The efficient microbial fermentation of hexoses and pentoses resulting from the pretreatment of lingocellulosic materials is essential for the success of these processes.

Results: Conversion of arabinose and glucose to hydrogen, by extreme thermophilic, anaerobic, mixed cultures was studied in continuous (70°C, pH 5.5) and batch (70°C, pH 5.5 and pH 7) assays. Two expanded granular sludge bed (EGSB) reactors, Rarab and Rgluc, were continuously fed with arabinose and glucose, respectively. No significant differences in reactor performance were observed for arabinose and glucose organic loading rates (OLR) ranging from 4.3 to 7.1 kgCOD m-3 d-1. However, for an OLR of 14.2 kgCOD m-3 d-1, hydrogen production rate and hydrogen yield were higher in Rarab than in Rgluc (average hydrogen production rate of 3.2 and 2.0 LH2 L-1 d-1 and hydrogen yield of 1.10 and 0.75 molH2 mol-1substrate for Rarab and Rgluc, respectively). Lower hydrogen production in Rgluc was associated with higher lactate production. Denaturing gradient gel electrophoresis (DGGE) results revealed no significant difference on the bacterial community composition between operational periods and between the reactors. Increased hydrogen production was observed in batch experiments when hydrogen partial pressure was kept low, both with arabinose and glucose as substrate. Sugars were completely consumed and hydrogen production stimulated (62% higher) when pH 7 was used instead of pH 5.5.

Conclusions: Continuous hydrogen production rate from arabinose was significantly higher than from glucose, when higher organic loading rate was used. The effect of hydrogen partial pressure on hydrogen production from glucose in batch mode was related to the extent of sugar utilization and not to the efficiency of substrate conversion to hydrogen. Furthermore, at pH 7.0, sugars uptake, hydrogen production and yield were higher than at pH 5.5, with both arabinose and glucose as substrates.

No MeSH data available.