title: Enhancement of 1,3-Dihydroxyacetone Production fromGluconobacter oxydansby Combined Mutagenesis.
abstract: Wild strain L-6 was subjected to combined mutagenesis, including UV irradiation, atmospheric and room temperature plasma, and ion beam implantation, to increase the yield of 1,3-dihydroxyacetone (DHA). With application of a high-throughput screening method, mutantGluconobacter oxydansI-2-239 with a DHA productivity of 103.5 g/l in flask-shake fermentation was finally obtained with the starting glycerol concentration of 120 g/l, which was 115.7% higher than the wild strain. The cultivation time also decreased from 54 h to 36 h. Compared with the wild strain, a dramatic increase in enzyme activity was observed for the mutant strain, although the increase in biomass was limited. DNA and amino acid sequence alignment revealed 11 nucleotide substitutions and 10 amino acid substitutions between thesldABof strains L-6 and I-2-239. Simulation of the 3-D structure and prediction of active site residues and PQQ binding site residues suggested that these mutations were mainly related to PQQ binding, which was speculated to be favorable for the catalyzing capacity of glycerol dehydrogenase. RT-qPCR assay indicated that the transcription levels ofsldAandsldBin the mutant strain were respectively 4.8-fold and 5.4-fold higher than that in the wild strain, suggesting another possible reason for the increased DHA productivity of the mutant strain.
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Lin
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Liu
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Guangrong
authors.initials: G
authors.lastname: Xie
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Penghua
authors.initials: P
authors.lastname: Li
authors.affiliation: School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004098:Dihydroxyacetone / Q000096:biosynthesis*; D005285:Fermentation; D020600:Gluconobacter oxydans / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D016296:Mutagenesis; D009154:Mutation; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D013401:Sugar Alcohol Dehydrogenases; C020672:glycerol dehydrogenase; D004098:Dihydroxyacetone
keywords: 1,3-Dihydroxyacetone; bioconversion; combined mutagenesis; enzyme activity; fermentation; glycerol