Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be aff...Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be affected by its lactate fraction.The efficiency of lactyl-CoA biosynthesis from intracellular lactate significantly affected the microbial synthesis of P(LA-co-3HB).Two CoA transferases from Anaerotignum lactatifermentans and Bacillota bacterium were selected for use in copolymer biosynthesis from 11 candidates.We found that cotAl enhanced the lactate fraction by 31.56%compared to that of the frequently used modified form of propionyl-CoA transferase from Anaerotignum propionicum.In addition,utilizing xylose as a favorable carbon source and blocking the lactate degradation pathway further enhanced the lactate fraction to 30.42 mol%and 52.84 mol%,respectively.Furthermore,when a 5 L bioreactor was used for fermentation utilizing xylose as a carbon source,the engineered strain produced 60.60 wt%P(46.40 mol%LA-co-3HB),which was similar to the results of our flask experiments.Our results indicate that the application of new CoA transferases has great potential for the biosynthesis of other lactate-based copolymers.展开更多
Quantum chemical calculations of the structures and cation-anion interaction of 1-ethyl-3-methylimidazolium lactate ([Emim][LAC]) ion pair at the B3LYP/6-31++G** theoretical level were performed. The relevant geometri...Quantum chemical calculations of the structures and cation-anion interaction of 1-ethyl-3-methylimidazolium lactate ([Emim][LAC]) ion pair at the B3LYP/6-31++G** theoretical level were performed. The relevant geometrical characteristics, energy properties, intermolecular H-bonds (H-bonds), and calculated IR vibrations with respect to isolated ions were systematically discussed. The natural bond orbital (NBO) and atoms in molecule (AIM) analyses were also employed to understand the nature of the interactions between cation and anion. The five most stable geometries were verified by analyzing the relative energies and interaction energies. It was found that the most of the C-H···O intermolecular H-bonds interactions in five stable conformers have some covalent character in nature. The elongation and red shift in IR spectrum of C-H bonds which involve in H-bonds is proved by electron transfers from the lone pairs of the carbonyl O atom of [LAC] to the C-H antibonding orbital of the [Emim]+. The interaction modes are more favorable when the carbonyl O atoms of [LAC] interact with the C2-H of the imidazolium ring and the C-H of the ethyl group through the formation of triple H-bonds.展开更多
基金supported by the National Natural Science Foundation of China(22278137)the National Key R&D Program of China(2021YFC2103500)Partially supported by Open Funding Project of the State Key Laboratory of Bioreactor Engineering.
文摘Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be affected by its lactate fraction.The efficiency of lactyl-CoA biosynthesis from intracellular lactate significantly affected the microbial synthesis of P(LA-co-3HB).Two CoA transferases from Anaerotignum lactatifermentans and Bacillota bacterium were selected for use in copolymer biosynthesis from 11 candidates.We found that cotAl enhanced the lactate fraction by 31.56%compared to that of the frequently used modified form of propionyl-CoA transferase from Anaerotignum propionicum.In addition,utilizing xylose as a favorable carbon source and blocking the lactate degradation pathway further enhanced the lactate fraction to 30.42 mol%and 52.84 mol%,respectively.Furthermore,when a 5 L bioreactor was used for fermentation utilizing xylose as a carbon source,the engineered strain produced 60.60 wt%P(46.40 mol%LA-co-3HB),which was similar to the results of our flask experiments.Our results indicate that the application of new CoA transferases has great potential for the biosynthesis of other lactate-based copolymers.
基金supported by the National Basic Research Program of China (2009CB219901)the National Natural Scientific Fund of China(21073194, 21106146)
文摘Quantum chemical calculations of the structures and cation-anion interaction of 1-ethyl-3-methylimidazolium lactate ([Emim][LAC]) ion pair at the B3LYP/6-31++G** theoretical level were performed. The relevant geometrical characteristics, energy properties, intermolecular H-bonds (H-bonds), and calculated IR vibrations with respect to isolated ions were systematically discussed. The natural bond orbital (NBO) and atoms in molecule (AIM) analyses were also employed to understand the nature of the interactions between cation and anion. The five most stable geometries were verified by analyzing the relative energies and interaction energies. It was found that the most of the C-H···O intermolecular H-bonds interactions in five stable conformers have some covalent character in nature. The elongation and red shift in IR spectrum of C-H bonds which involve in H-bonds is proved by electron transfers from the lone pairs of the carbonyl O atom of [LAC] to the C-H antibonding orbital of the [Emim]+. The interaction modes are more favorable when the carbonyl O atoms of [LAC] interact with the C2-H of the imidazolium ring and the C-H of the ethyl group through the formation of triple H-bonds.
