Cellulose is a homo polymer composed of glucose subunits, while
hemicellulose is heterogeneous, mainly composed of xylose subunits,
and considered to be the second most abundant sugar in
nature after glucose (6,7). The percentage of cellulose and hemicellulose
in lignocellulosic biomass are dependent on the type of
lignocellulosic biomass, i.e., cottonseed hairs contain 80e95% cellulose
and 5e20% hemicellulose; leaves contain 15e20% cellulose
and 80e85% hemicellulose; and grasses contain 25e40% cellulose
and 25e50% hemicellulose (4,6). Complete hydrolysates derived
from various lignocellulosic biomasses show different ratios of
glucose and xylose. However, effective utilization of lignocellulosic
biomass for lactic acid production is hindered by a number of difficulties,
mainly because most lactic acid bacteria (LAB) cannot
utilize xylose. In addition, carbon catabolite repression (CCR) is
observed in most LAB, where preferred sugars such as glucose
repress the utilization of other non-favourable sugars such as
xylose and arabinose (8,9). Furthermore, the formation of byproducts
limits the yield of lactic acid and increases the purification cost
Cellulose is a homo polymer composed of glucose subunits, whilehemicellulose is heterogeneous, mainly composed of xylose subunits,and considered to be the second most abundant sugar innature after glucose (6,7). The percentage of cellulose and hemicellulosein lignocellulosic biomass are dependent on the type oflignocellulosic biomass, i.e., cottonseed hairs contain 80e95% celluloseand 5e20% hemicellulose; leaves contain 15e20% celluloseand 80e85% hemicellulose; and grasses contain 25e40% celluloseand 25e50% hemicellulose (4,6). Complete hydrolysates derivedfrom various lignocellulosic biomasses show different ratios ofglucose and xylose. However, effective utilization of lignocellulosicbiomass for lactic acid production is hindered by a number of difficulties,mainly because most lactic acid bacteria (LAB) cannotutilize xylose. In addition, carbon catabolite repression (CCR) isobserved in most LAB, where preferred sugars such as glucoserepress the utilization of other non-favourable sugars such asxylose and arabinose (8,9). Furthermore, the formation of byproductslimits the yield of lactic acid and increases the purification cost
การแปล กรุณารอสักครู่..
