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Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol.

Gupta R, Kumar S, Gomes J, Kuhad RC - Biotechnol Biofuels (2012)

Bottom Line: Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L.Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.Restricting the process to suitable kinetic regimes could result in higher conversion rates.

View Article: PubMed Central - HTML - PubMed

Affiliation: Lignocellulose Biotechnology Laboratory, Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India. kuhad85@gmail.com.

ABSTRACT

Background: Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach.

Results: The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v) and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.

Conclusion: Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.

No MeSH data available.


Comparative profiling of batch and fed-batch enzymatic saccharification (A) glucose production, (B) cellulose conversion.
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Figure 4: Comparative profiling of batch and fed-batch enzymatic saccharification (A) glucose production, (B) cellulose conversion.

Mentions: A comparison between batch and fed-batch enzymatic hydrolysis was made to determine which had a higher cellulose conversion. The results showed that in fed-batch operation at Sc = 20%, the remaining insoluble solids in the reaction slurry was 65.59 g/L. While in contrast, during the batch enzymatic hydrolysis at S4,0 = 20% (w/v), the concentration of remaining insoluble solid was 107.29 g/L. The time profiles of glucose concentration and cellulose conversion levels for both batch (S4,0 = 20%) and fed-batch (Sc = 20%) were plotted in Figure 4a-b. The final sugar concentration for batch and fed-batch were 80.78 g/L and 127. 0 g/L (Figure 4a), while the cellulose conversion was 40.39% and 63.56%, respectively (Figure 4b). These results showed that intermittent addition of solids in a repeated fed-batch mode, resulted in better conversion compared to the addition of an equal amount once at the beginning of a batch.


Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol.

Gupta R, Kumar S, Gomes J, Kuhad RC - Biotechnol Biofuels (2012)

Comparative profiling of batch and fed-batch enzymatic saccharification (A) glucose production, (B) cellulose conversion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369211&req=5

Figure 4: Comparative profiling of batch and fed-batch enzymatic saccharification (A) glucose production, (B) cellulose conversion.
Mentions: A comparison between batch and fed-batch enzymatic hydrolysis was made to determine which had a higher cellulose conversion. The results showed that in fed-batch operation at Sc = 20%, the remaining insoluble solids in the reaction slurry was 65.59 g/L. While in contrast, during the batch enzymatic hydrolysis at S4,0 = 20% (w/v), the concentration of remaining insoluble solid was 107.29 g/L. The time profiles of glucose concentration and cellulose conversion levels for both batch (S4,0 = 20%) and fed-batch (Sc = 20%) were plotted in Figure 4a-b. The final sugar concentration for batch and fed-batch were 80.78 g/L and 127. 0 g/L (Figure 4a), while the cellulose conversion was 40.39% and 63.56%, respectively (Figure 4b). These results showed that intermittent addition of solids in a repeated fed-batch mode, resulted in better conversion compared to the addition of an equal amount once at the beginning of a batch.

Bottom Line: Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L.Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.Restricting the process to suitable kinetic regimes could result in higher conversion rates.

View Article: PubMed Central - HTML - PubMed

Affiliation: Lignocellulose Biotechnology Laboratory, Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India. kuhad85@gmail.com.

ABSTRACT

Background: Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach.

Results: The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v) and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.

Conclusion: Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.

No MeSH data available.