accumulation via strategies like increasing glucan storage and decreasing starch
degradation. The starch forms around a crystallizing nucleus and is present as an
amorphous starch grain. When a chloroplast gathers enough starch, it may become
an amyloplast. However, the detailed changes in enzymatic activity and metabolic
flux of carbohydrate biosynthesis of microalgae are poorly understood. The
manipulation of the carbohydrate metabolisms of microalgae by genetic engineering has also been proposed. With the development of genetic engineering of
microalgae, and a better understanding of the biochemistry of microalgae carbohydrate metabolisms, superior strains for carbohydrate accumulation could be
developed.
Except the starch in plastids, microalgal extracellular coverings (cell wall) are
another carbohydrate-rich part, which could be transformed to biofuel. However,
the compositions of microalgal extracellular coverings are diverse by species.
Among them, cellulose is one of the main fermentable carbohydrates in most of
green algae. Cellulose synthesis is a complicated process that includes many
enzymatic reactions. The starting substrate for cellulose synthesis is UDP-glucose,
which is formed from the reaction of UDP and fructose catalyzed by sucrose
synthase. Despite the understanding of main carbohydrate metabolism in microalgae, in-depth knowledge on its regulation is still lacking. It is important to integrate
updated information of genomic sequences, transcriptomes, proteomes, and metabolomes data at systems level to meet the challenges on economic biofuels production from microalgae.
Fig. 2 Proposal of carbohydrate metabolism in green algae (adapted from Chen et al. 2013)
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degradation. The starch forms around a crystallizing nucleus and is present as an
amorphous starch grain. When a chloroplast gathers enough starch, it may become
an amyloplast. However, the detailed changes in enzymatic activity and metabolic
flux of carbohydrate biosynthesis of microalgae are poorly understood. The
manipulation of the carbohydrate metabolisms of microalgae by genetic engineering has also been proposed. With the development of genetic engineering of
microalgae, and a better understanding of the biochemistry of microalgae carbohydrate metabolisms, superior strains for carbohydrate accumulation could be
developed.
Except the starch in plastids, microalgal extracellular coverings (cell wall) are
another carbohydrate-rich part, which could be transformed to biofuel. However,
the compositions of microalgal extracellular coverings are diverse by species.
Among them, cellulose is one of the main fermentable carbohydrates in most of
green algae. Cellulose synthesis is a complicated process that includes many
enzymatic reactions. The starting substrate for cellulose synthesis is UDP-glucose,
which is formed from the reaction of UDP and fructose catalyzed by sucrose
synthase. Despite the understanding of main carbohydrate metabolism in microalgae, in-depth knowledge on its regulation is still lacking. It is important to integrate
updated information of genomic sequences, transcriptomes, proteomes, and metabolomes data at systems level to meet the challenges on economic biofuels production from microalgae.
Fig. 2 Proposal of carbohydrate metabolism in green algae (adapted from Chen et al. 2013)
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