Calorespirometric investigation of Streptococcus zooepidemicus metabolism: Thermodynamics of anabolic payload contribution by growth and hyaluronic acid synthesis

Abstract

Thermodynamic analysis of carbon flux competing for pathways of S. zooepidemicus in the production of catabolic (Lactic acid) and anabolic (Biomass and Hyaluronic Acid) products is investigated to assimilate the thermodynamic advantages of biopolymer production. Calorespirometry was employed to fingerprint the on-going HA production process and to predict reliable estimation of catabolic and anabolic product yields. This study accomplished the HA production at different initial glucose concentrations, S<inf>0</inf> (10–60 g/L) to subject different levels of anabolic burden on S. zooepidemicus. Anabolic payload comprising Biomass and HA yields showed a concomitant decrease with respect to the increased concentration of S<inf>0</inf>. Chemical entropy exported over the cell surface in the form of LA production exhibited an increasing trend at different levels of glucose, thus reducing the total yields of biomass and HA. Thermodynamically anabolic load contributed by biomass and HA production found to have minor influence over the driving force of S. zooepidemicus metabolism due to their lower yields. The entropy contribution to the overall driving force is significant (T?S<inf>X</inf>= [Formula presented] ?<inf>r</inf>G<inf>X</inf>) at the higher biomass yields. This study allows the prediction of optimum biomass yield towards enhanced HA production and addresses the scope of ‘thermodynamic constraints’ application in real-time process monitoring and control using data reconciliation strategy in the near future. © 2019 Elsevier B.V.