Intracellular Lipid Production from Lignin Model Monomers by Acinetobacter baylyi ADP1
Luo, Jin Jr (2016)
Luo, Jin Jr
2016
Master's Degree Programme in Science and Bioengineering
Luonnontieteiden tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2016-11-09
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201610214622
https://urn.fi/URN:NBN:fi:tty-201610214622
Tiivistelmä
Lignin is a complex aromatic polymer consisting of phenylpropanoid units (C9 units), which, together with cellulose and hemicellulose, is the major component of lignocellulosic biomass. The cellulose and hemicellulose are usually separated from lignocellulosic biomass and converted into fuels and chemicals, whereas the lignin is usually regarded as unwelcome by-product due to its recalcitrance and inherent heterogeneity. Thus it is necessary to further exploit the value of lignin. The aim of this study is to explore the conversion of lignin model monomers into wax ester, an important industrial raw material, through microbial conversion.
The present work shows that Acinetobacter baylyi ADP1 can accumulate wax ester by using lignin monomers as carbon sources under nitrogen-limited condition. To improve the consumption of lignin monomers, the crc gene, which is involved in catabolite repression under the presence of acetate, was knocked out, and the resulting strain was designated as crc strain. The wax ester production was first conducted with wild type ADP1 using coumaric acid and ferulic acid as sole carbon source respectively. Wax ester productions of 16.9 and 14.4 μmol/100 mg dried biomass (0.169 and 0.144 mmol/g freeze-dried biomass) were obtained respectively. Co-utilization of acetate, coumaric acid and ferulic acid was conducted with both wild type and crc strain. Wild type ADP1 accumulated wax ester up to 29.2 μmol/100 mg dried biomass (0.292 mmol/g freeze-dried biomass), which was much higher than crc strain (0.1125 mmol/g freeze-dried biomass). In crc strain, the catabolite repression caused by acetate seemed to be relieved but the consumption rate of carbon source was very low. The reason still needs to be further explored.
The present work shows that Acinetobacter baylyi ADP1 can accumulate wax ester by using lignin monomers as carbon sources under nitrogen-limited condition. To improve the consumption of lignin monomers, the crc gene, which is involved in catabolite repression under the presence of acetate, was knocked out, and the resulting strain was designated as crc strain. The wax ester production was first conducted with wild type ADP1 using coumaric acid and ferulic acid as sole carbon source respectively. Wax ester productions of 16.9 and 14.4 μmol/100 mg dried biomass (0.169 and 0.144 mmol/g freeze-dried biomass) were obtained respectively. Co-utilization of acetate, coumaric acid and ferulic acid was conducted with both wild type and crc strain. Wild type ADP1 accumulated wax ester up to 29.2 μmol/100 mg dried biomass (0.292 mmol/g freeze-dried biomass), which was much higher than crc strain (0.1125 mmol/g freeze-dried biomass). In crc strain, the catabolite repression caused by acetate seemed to be relieved but the consumption rate of carbon source was very low. The reason still needs to be further explored.