Quantitative physiology of non-energy-limited retentostat cultures ofSaccharomyces cerevisiaeat near-zero specific growth rates

Abstract

excess 12 13 14 15 16 17 18 19 20 21 a Current address: Royal Haskoning DHV, George Hintzenweg 85, 3009 AM Rotterdam, The Netherlands.prevent loss of feedstock to biomass production. Establishing S. cerevisiae cultures in which 46 growth is restricted by the limited supply of a non-energy substrate could therefore have a 47 wide range of industrial applications, but remains largely unexplored. In this work we 48 accomplished near-zero growth of S. cerevisiae through limited supply of a non-energy 49 nutrient, namely the nitrogen or phosphorus source and carried out a quantitative 50 physiology study of the cells under these conditions. The possibility to achieve near-zero-51 growth S. cerevisiae cultures through limited supply of a non-energy nutrient may offer 52 interesting prospects to develop novel fermentation processes for high-yield production of 53 bio-based chemicals. 54 Growth and viability in ammonium-and phosphate-limited retentostat cultures130 Retentostat cultures were started by redirecting the effluent of steady-state ammonium-or 131 phosphate-limited chemostat cultures, grown at a dilution rate of 0.025 h -1 , through a 132 membrane filter unit placed inside the reactor (see Materials and Methods). Replicate 133 ammonium-limited retentostats were operated for 220 h with full biomass retention, after 134 which fouling caused the membrane filters to clog. Membrane fouling was not observed in 135 the phosphate-limited retentostats, which were operated with full biomass retention until, 136 after 400 h, the biomass concentration had reached a stable value. 137

Characterising the metabolic rewiring of extremely slow growingKomagataella phaffii

“…Furthermore, non-energy-limited cultivations with nitrogen and phosphorous source limitation have been performed (Y. Liu, el Masoudi, Pronk, & van Gulik 2019). In ammonium-limited retentostat cultivations, production of succinic acid was uncoupled from growth, achieving a succinic acid yield on glucose of 0.61 mol mol −1 for over 500 h, albeit with accumulation of large quantities of inviable biomass (Y.…”