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Evaluation of ammonia fibre expansion (AFEX) pretreatment for enzymatic hydrolysis of switchgrass harvested in different seasons and locations.

Bals B, Rogers C, Jin M, Balan V, Dale B - Biotechnol Biofuels (2010)

Bottom Line: All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.Each harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars.Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.

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Affiliation: Biomass Conversion Research Laboratory, Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, USA.

ABSTRACT

Background: When producing biofuels from dedicated feedstock, agronomic factors such as harvest time and location can impact the downstream production. Thus, this paper studies the effectiveness of ammonia fibre expansion (AFEX) pretreatment on two harvest times (July and October) and ecotypes/locations (Cave-in-Rock (CIR) harvested in Michigan and Alamo harvested in Alabama) for switchgrass (Panicum virgatum).

Results: Both harvest date and ecotype/location determine the pretreatment conditions that produce maximum sugar yields. There was a high degree of correlation between glucose and xylose released regardless of the harvest, pretreatment conditions, or enzyme formulation. Enzyme formulation that produced maximum sugar yields was the same across all harvests except for the CIR October harvest. The least mature sample, the July harvest of CIR switchgrass, released the most sugars (520 g/kg biomass) during enzymatic hydrolysis while requiring the least severe pretreatment conditions. In contrast, the most mature harvest released the least amount of sugars (410 g/kg biomass). All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.

Conclusions: Each harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars. Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.

No MeSH data available.


Fermentation profiles. Glucose (blue), xylose (red), and ethanol (green) concentrations achieved during fermentation of switchgrass. All fermentations were performed using Saccharomyces cerevisiae at 30°C and shaken at 150 rpm. Switchgrass hydrolysate after 72 h of enzymatic hydrolysis at 20% solid loading was used except for the October harvest of Alamo switchgrass, where the solid loading was 10%. Data points are the average of duplicate fermentations.
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Figure 4: Fermentation profiles. Glucose (blue), xylose (red), and ethanol (green) concentrations achieved during fermentation of switchgrass. All fermentations were performed using Saccharomyces cerevisiae at 30°C and shaken at 150 rpm. Switchgrass hydrolysate after 72 h of enzymatic hydrolysis at 20% solid loading was used except for the October harvest of Alamo switchgrass, where the solid loading was 10%. Data points are the average of duplicate fermentations.

Mentions: Glucose, xylose, and ethanol concentrations for fermentations of the four switchgrass harvests are shown in Figure 4. Metabolic yield (defined as a percentage of the theoretical amount of ethanol produced from the consumption of sugars) was high in all cases, ranging from 87% for the Alamo July harvest to 97% for the CIR July harvest. Glucose fermentation was also complete, with virtually all glucose consumed within 48 h. However, a lengthy lag phase that lasted approximately 10 to 24 h was present in all switchgrass harvests. This may be due to the strain being prepared on YEP media rather than hydrolysate, and may be eliminated if the strain were adapted to AFEX hydrolysate prior to inoculation [26]. The three hydrolysates at 20% solid loading all achieved final ethanol concentrations in excess of 30 g/l. While this value is lower than the 40 g/l threshold generally accepted for ethanol production [27], this indicates the fermentability of AFEX-treated switchgrass, and further optimisation and technology improvements will likely improve these results.


Evaluation of ammonia fibre expansion (AFEX) pretreatment for enzymatic hydrolysis of switchgrass harvested in different seasons and locations.

Bals B, Rogers C, Jin M, Balan V, Dale B - Biotechnol Biofuels (2010)

Fermentation profiles. Glucose (blue), xylose (red), and ethanol (green) concentrations achieved during fermentation of switchgrass. All fermentations were performed using Saccharomyces cerevisiae at 30°C and shaken at 150 rpm. Switchgrass hydrolysate after 72 h of enzymatic hydrolysis at 20% solid loading was used except for the October harvest of Alamo switchgrass, where the solid loading was 10%. Data points are the average of duplicate fermentations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823726&req=5

Figure 4: Fermentation profiles. Glucose (blue), xylose (red), and ethanol (green) concentrations achieved during fermentation of switchgrass. All fermentations were performed using Saccharomyces cerevisiae at 30°C and shaken at 150 rpm. Switchgrass hydrolysate after 72 h of enzymatic hydrolysis at 20% solid loading was used except for the October harvest of Alamo switchgrass, where the solid loading was 10%. Data points are the average of duplicate fermentations.
Mentions: Glucose, xylose, and ethanol concentrations for fermentations of the four switchgrass harvests are shown in Figure 4. Metabolic yield (defined as a percentage of the theoretical amount of ethanol produced from the consumption of sugars) was high in all cases, ranging from 87% for the Alamo July harvest to 97% for the CIR July harvest. Glucose fermentation was also complete, with virtually all glucose consumed within 48 h. However, a lengthy lag phase that lasted approximately 10 to 24 h was present in all switchgrass harvests. This may be due to the strain being prepared on YEP media rather than hydrolysate, and may be eliminated if the strain were adapted to AFEX hydrolysate prior to inoculation [26]. The three hydrolysates at 20% solid loading all achieved final ethanol concentrations in excess of 30 g/l. While this value is lower than the 40 g/l threshold generally accepted for ethanol production [27], this indicates the fermentability of AFEX-treated switchgrass, and further optimisation and technology improvements will likely improve these results.

Bottom Line: All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.Each harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars.Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biomass Conversion Research Laboratory, Department of Chemical Engineering and Material Science, Michigan State University, Lansing, MI, USA.

ABSTRACT

Background: When producing biofuels from dedicated feedstock, agronomic factors such as harvest time and location can impact the downstream production. Thus, this paper studies the effectiveness of ammonia fibre expansion (AFEX) pretreatment on two harvest times (July and October) and ecotypes/locations (Cave-in-Rock (CIR) harvested in Michigan and Alamo harvested in Alabama) for switchgrass (Panicum virgatum).

Results: Both harvest date and ecotype/location determine the pretreatment conditions that produce maximum sugar yields. There was a high degree of correlation between glucose and xylose released regardless of the harvest, pretreatment conditions, or enzyme formulation. Enzyme formulation that produced maximum sugar yields was the same across all harvests except for the CIR October harvest. The least mature sample, the July harvest of CIR switchgrass, released the most sugars (520 g/kg biomass) during enzymatic hydrolysis while requiring the least severe pretreatment conditions. In contrast, the most mature harvest released the least amount of sugars (410 g/kg biomass). All hydrolysates were highly fermentable, although xylose utilisation in the July CIR hydrolysate was poor.

Conclusions: Each harvest type and location responded differently to AFEX pretreatment, although all harvests successfully produced fermentable sugars. Thus, it is necessary to consider an integrated approach between agricultural production and biochemical processing in order to insure optimal productivity.

No MeSH data available.