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Rational approach to improve ansamitocin P‐3 production by integrating pathway engineering and substrate feeding in Actinosynnema pretiosum
Author(s) -
Du ZhiQiang,
Zhong JianJiang
Publication year - 2018
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.26775
Subject(s) - titer , bioreactor , substrate (aquarium) , fermentation , isobutanol , chemistry , biochemistry , metabolic engineering , recombinant dna , strain (injury) , biology , stereochemistry , enzyme , gene , organic chemistry , alcohol , virus , ecology , virology , anatomy
Ansamitocin P‐3 (AP‐3) produced by Actinosynnema pretiosum is an important antitumor agent for cancer treatment, but its market supply suffers from a low production titer. The role of AP‐3 unusual glycolate unit supply on its biosynthesis was investigated in this work by overexpressing the responsible gene cluster asm13‐17 in A. pretiosum (WT). As a result, the accumulation of AP‐3 and its intermediate glyceryl‐ S ‐ACP in the asm13‐17 ‐overexpressed strain (O asm13‐17 ) versus WT was enhanced by 1.94 and 1.49‐fold, respectively. To provide a higher supply of another precursor 3‐amino‐5‐hydroxybenzoic acid, asmUdpg was also overexpressed in O asm13‐17 (O asm13‐17:asmUdpg ), and an improved AP‐3 titer of 680.5 mg/L was achieved in shake flasks. To further enhance the AP‐3 titer, a rational fed‐batch strategy was developed in bioreactor fermentation of O asm13‐17:asmUdpg ; and by pulse feeding 15 g/L fructose and 1.64 g/L isobutanol at 60, 96, and 120 hr, the AP‐3 production level reached 757.7 mg/L, which is much higher than ever reported in bioreactors. This work demonstrated that a rational approach combining precursor pathway engineering with substrate feeding was very effective in enhancing the AP‐3 titer, and this enabling methodology would be helpful to industrial production of this eye‐catching drug.