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The metabolic characteristicsof high‐production vitamin B 12 by Pseudomonas denitrificans under dissolved oxygen step‐wise reduction
Author(s) -
Peng Weifu,
Cheng Xin,
Zhang Hongyan,
Li KunTai
Publication year - 2014
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.4219
Subject(s) - fermentation , biochemistry , paracoccus denitrificans , metabolic pathway , citric acid cycle , chemistry , biosynthesis , porphobilinogen synthase , metabolism , metabolic flux analysis , enzyme , dehydratase
BACKGROUND Previous research proved that fermentation via dissolved oxygen (DO) step‐wise reduction was favorable for vitamin B 12 productivity by Pseudomonas denitrificans , but the high‐production mechanism is still unclear. Based on this fact, P. denitrificans metabolic characteristics under different DO supply models were investigated in a 5 L fermenter by assaying the activities of the key enzymes involved in central carbon metabolism and the vitamin B 12 biosynthetic pathway . RESULTS Compared with fermentation processes under the DO‐stat strategy and DO step‐wise increase, it was found that DO step‐wise reduction for P. denitrificans fermentation could significantly strengthen the Embden–Meyerhof–Parnas flux and weaken the tricarboxylic acid cycle and hexose monophosphate pathway, but also facilitate the activities of δ‐aminolevulinic acid synthase and porphobilinogen synthase . CONCLUSIONS When P. denitrificans fermentation was implemented using DO step‐wise reduction, the metabolic characteristics indicated that more precursors for vitamin B 12 biosynthesis could be generated. As a result, a significant improvement in vitamin B 12 productivity was achieved (69.09 ± 4.48 mg L −1 ). © 2013 Society of Chemical Industry