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z*h
发帖数: 773 | 1 【 以下文字转载自 ECUST 讨论区 】
发信人: zyh (CH2O), 信区: ECUST
标 题: From nonfood biomass to starch
发信站: BBS 未名空间站 (Mon Apr 15 18:26:35 2013, 美东)
Abstract
The global demand for food could double in another 40 y owing to growth in
the population and food consumption per capita. To meet the world’s future
food and sustainability needs for biofuels and renewable materials, the
production of starch-rich cereals and cellulose-rich bioenergy plants must
grow substantially while minimizing agriculture’s environmental footprint
and conserving biodiversity. Here we demonstrate one-pot enzymatic
conversion of pretreated biomass to starch through a nonnatural synthetic
enzymatic pathway composed of endoglucanase, cellobiohydrolyase, cellobiose
phosphorylase, and alpha-glucan phosphorylase originating from bacterial,
fungal, and plant sources. A special polypeptide cap in potato alpha-glucan
phosphorylase was essential to push a partially hydrolyzed intermediate of
cellulose forward to the synthesis of amylose. Up to 30% of the
anhydroglucose units in cellulose were converted to starch; the remaining
cellulose was hydrolyzed to glucose suitable for ethanol production by yeast
in the same bioreactor. Next-generation biorefineries based on simultaneous
enzymatic biotransformation and microbial fermentation could address the
food, biofuels, and environment trilemma.
http://www.pnas.org/content/early/2013/04/12/1302420110 | S*****n
发帖数: 6055 | 2 cool!
future
【在 z*h 的大作中提到】
: 【 以下文字转载自 ECUST 讨论区 】
: 发信人: zyh (CH2O), 信区: ECUST
: 标 题: From nonfood biomass to starch
: 发信站: BBS 未名空间站 (Mon Apr 15 18:26:35 2013, 美东)
: Abstract
: The global demand for food could double in another 40 y owing to growth in
: the population and food consumption per capita. To meet the world’s future
: food and sustainability needs for biofuels and renewable materials, the
: production of starch-rich cereals and cellulose-rich bioenergy plants must
: grow substantially while minimizing agriculture’s environmental footprint
| f****w
发帖数: 407 | 3 Niu!
future
【在 z*h 的大作中提到】
: 【 以下文字转载自 ECUST 讨论区 】
: 发信人: zyh (CH2O), 信区: ECUST
: 标 题: From nonfood biomass to starch
: 发信站: BBS 未名空间站 (Mon Apr 15 18:26:35 2013, 美东)
: Abstract
: The global demand for food could double in another 40 y owing to growth in
: the population and food consumption per capita. To meet the world’s future
: food and sustainability needs for biofuels and renewable materials, the
: production of starch-rich cereals and cellulose-rich bioenergy plants must
: grow substantially while minimizing agriculture’s environmental footprint
| w********h
发帖数: 12367 | 4 cong, yh!
future
【在 z*h 的大作中提到】
: 【 以下文字转载自 ECUST 讨论区 】
: 发信人: zyh (CH2O), 信区: ECUST
: 标 题: From nonfood biomass to starch
: 发信站: BBS 未名空间站 (Mon Apr 15 18:26:35 2013, 美东)
: Abstract
: The global demand for food could double in another 40 y owing to growth in
: the population and food consumption per capita. To meet the world’s future
: food and sustainability needs for biofuels and renewable materials, the
: production of starch-rich cereals and cellulose-rich bioenergy plants must
: grow substantially while minimizing agriculture’s environmental footprint
| t*****e
发帖数: 3544 | | s*******y
发帖数: 572 | | z*h
发帖数: 773 | 7 Cutting it from discussion.
This cellulose-to-amylose biotransformation could be scaled up by increasing
the stability of CBP and PGP and decreasing their production costs in terms
of $/kg enzyme (Fig. S6) because this combined cellulose-hydrolyzing and
starch-synthesizing enzyme cocktail did not involve any labile coenzymes [e.
g., CoA and NAD(P)] (Fig. 1A); no glucose released from the cellulose was
wasted (Fig. 1); only two more enzymes were added and they can be re-used
easily by a magnetic force (Fig. 4); and no energy or costly reagents were
added. When both CBP-PGP enzymes have total turnover number (TTN) values of
2.6 × 106 mol of product per mole of enzyme and their cost is 20 US dollars
per kg of enzyme, the extra enzyme cost compared to SSF in biorefineries
would be one cent per kg of amylose synthesized. When enzyme costs are lower
than $20/kg and/or TTN values are higher than 2.6 × 106, the enzyme
expenditure could be decreased drastically (Fig. S6). Wild-type thermophilic
CBP has an estimated TTN value of approximately 2 ×106 at 30oC (34),
while more stable engineered CBP by combining directed evolution and
rational design has an enhanced TTN value of approximately 2 ×107 by a
factor of approximately 10 (42). Wild-type PGP has an estimated TTN value of
approximately 6×104 at 30oC. Via directed evolution, a PGP mutant has a
nearly two orders of magnitude enhancement in TTN values, being
approximately 1.7 ×106 (43). By considering the stability of immobilized
glucose isomerase (29) and other immobilized thermophilic enzymes (44),
further stability improvement of CBP and PGP is expected to be achieved by
more rounds of mutagenesis plus enzyme immobilization soon. Another scale-up
challenge could be low-cost production of CBP and PGP. Considering the
production costs of bulk enzymes: such as cellulase and protease (i.e., $~
10/kg) (45), and relatively fine enzymes used for biocatalysis (i.e., $~100/
kg) (30, 46), the above economic analysis based on enzyme stability and
enzyme production costs could be feasible after more R&D efforts. In
partially support to it, enzyme costs in the enzymatic hydrolysis of starch
are only 0.3-0.6 cents per kg of starch hydrolyzed (29). | T*****9
发帖数: 3015 | 8 感觉就是对过去的人吃树皮的一种高级进化……
【在 s*******y 的大作中提到】
: 专业的人活着作者自己点评一下？
| l*********1
发帖数: 351 | 9 Cong!
future
【在 z*h 的大作中提到】
: Cutting it from discussion.
: This cellulose-to-amylose biotransformation could be scaled up by increasing
: the stability of CBP and PGP and decreasing their production costs in terms
: of $/kg enzyme (Fig. S6) because this combined cellulose-hydrolyzing and
: starch-synthesizing enzyme cocktail did not involve any labile coenzymes [e.
: g., CoA and NAD(P)] (Fig. 1A); no glucose released from the cellulose was
: wasted (Fig. 1); only two more enzymes were added and they can be re-used
: easily by a magnetic force (Fig. 4); and no energy or costly reagents were
: added. When both CBP-PGP enzymes have total turnover number (TTN) values of
: 2.6 × 106 mol of product per mole of enzyme and their cost is 20 US dollars
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