scholarly journals Enhancing the Production of Polyhydroxyalkanoate Biopolymer by Azohydromonas Australica Using a Simple Empty and Fill Bioreactor Cultivation Strategy

2018 ◽  
Vol 31 (4) ◽  
pp. 479-485 ◽  
Author(s):  
G. Gahlawat
2021 ◽  
Vol 9 (6) ◽  
pp. 1110
Author(s):  
Ángel Córcoles García ◽  
Peter Hauptmann ◽  
Peter Neubauer

Insufficient mixing in large-scale bioreactors provokes gradient zones of substrate, dissolved oxygen (DO), pH, and other parameters. E. coli responds to a high glucose, low oxygen feeding zone with the accumulation of mixed acid fermentation products, especially formate, but also with the synthesis of non-canonical amino acids, such as norvaline, norleucine and β-methylnorleucine. These amino acids can be mis-incorporated into recombinant products, which causes a problem for pharmaceutical production whose solution is not trivial. While these effects can also be observed in scale down bioreactor systems, these are challenging to operate. Especially the high-throughput screening of clone libraries is not easy, as fed-batch cultivations would need to be controlled via repeated glucose pulses with simultaneous oxygen limitation, as has been demonstrated in well controlled robotic systems. Here we show that not only glucose pulses in combination with oxygen limitation can provoke the synthesis of these non-canonical branched-chain amino acids (ncBCAA), but also that pyruvate pulses produce the same effect. Therefore, we combined the enzyme-based glucose delivery method Enbase® in a PALL24 mini-bioreactor system and combined repeated pyruvate pulses with simultaneous reduction of the aeration rate. These cultivation conditions produced an increase in the non-canonical branched chain amino acids norvaline and norleucine in both the intracellular soluble protein and inclusion body fractions with mini-proinsulin as an example product, and this effect was verified in a 15 L stirred tank bioreactor (STR). To our opinion this cultivation strategy is easy to apply for the screening of strain libraries under standard laboratory conditions if no complex robotic and well controlled parallel cultivation devices are available.


2021 ◽  
Vol 234 ◽  
pp. 113908
Author(s):  
Xiang Wang ◽  
Man-Man Zhang ◽  
Si-Fen Liu ◽  
Rui-Lan Xu ◽  
Jin-Hua Mou ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document