Biomedical Engineering Reference
In-Depth Information
Table 6 Fermentative production of lactic acid using different hemicellulosic substrates
Raw material
Strain
Lactic acid
yield (g/g)
Lactic acid
concentration
(g/L)
Reference
Wheat bran hemicellulose
hydrolyzate
Lactobacillus
bifermentans
0.47
41.30
[
111
]
Wood hemicellulose
hydrolyzate
Rhizopus oryzae
0.26
19.13
[
113
]
Wheat straw hemicellulose
hydrolyzate
Lactobacillus
pentosus
0.90
6.70
[
116
]
Trimming vine shoots
hemicellulose hydrolyzate
Lactobacillus
pentosus
0.78
46.00
[
117
]
Barley bran hemicellulose
hydrolyzate
Lactobacillus
pentosus
0.57
33.70
[
118
]
Corncob hemicellulose
hydrolyzate
Lactobacillus
brevis
0.69
39.10
[
123
]
Corncob molasses
Bacillus sp.
0.81
74.70
[
124
]
approximately 20% by direct adaptation of Enterococcus faecalis to wood
hydrolyzate-based medium. Garde et al. [
116
] observed that neither L. pentosus
nor L. brevis was able to fully utilize the released sugars of hemicellulose after
acid treatment; however, lactic acid production could be increased to 95% of the
theoretical maximum yield by co-inoculation of the two strains.
In China, pure xylose, glucose-xylose mixture, and hemicellulose-derived sugar
mixtures have been used for lactic acid production [
119
-
124
]. More attention has
been paid to strain improvement for xylose utilization. R. oryzae RLC41-6 mutated
by means of low-energy ion beam implantation was found to be an efficient L-lactic
acid producer from xylose; under optimal conditions, L-lactic acid yield of 0.77 g/g
was achieved [
119
]. Bai et al. [
120
] obtained an adapted R. oryzae strain HZS6,
which had a significantly improved utilization of sugars from corncob hydrolyzate;
the final L-lactic acid concentration, yield, and productivity were twice that of its
parental strain. Guo et al. [
123
] isolated two strains of L. brevis from sour cabbage,
which exhibited the potential to completely utilize various sugars contained in
hemicellulose hydrolyzate, and was strongly resistant to the fermentation inhibitors
such as furfural; 39.1 g/L of lactic acid was finally achieved from dilute acid
hydrolyzate of corncobs which contained 46.4 g/L xylose, 4.0 g/L glucose, and
6.5 g/L arabinose. Wang et al. [
124
] used corncob molasses, containing a high
xylose content, for L-lactic acid production via a newly isolated xylose-utilizing
Bacillus sp. XZL9. A high concentration of L-lactic acid (74.7 g/L) was obtained
from corncob molasses (total sugars 91.4 g/L) under fed-batch fermentation.
Fumaric acid is another organic acid that can be obtained from hemicellulose
sugars. It is widely used in the food industry without limitations and is a valuable
intermediate for preparing edible products such as L-malic acid and L-aspartic acid.
With a double bond and two carboxylic groups, fumaric acid is an important inter-
mediate for polymer production, such as in the manufacture of synthetic resins and
biodegradable polymers. At present, all commercial fumaric acid is produced from
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