The response of Leuconostoc mesenteroides to low external oxidoreduction potential generated by hydrogen gas

Abstract

Aims:The physiological consequences of low external oxidoreduction potential in Leuconostoc mesenteroides were investigated. Methods and Results: Leuconostoc mesenteroides was grown under two initial oxidoreduction potential conditions (E h7 : +200 mV and )400 mV) using nitrogen and hydrogen as reducing agents. Growth was affected by E h7 ; the lag phase increased from 1 h at an initial E h7 of +200 mV to 6 h at an initial E h7 of )400 mV; the maximum specific growth rate at )400 mV was 68% of the one observed at +200 mV. The NADH/NAD + ratio and (NADH + NAD + ) pool were independent of the external E h7 . Conclusions: This study shows that changing the external oxidoreduction potential from +200 to )400 mV has a strong effect on the Leuc. mesenteroides physiology. The constancy of the maximum carbon and energetic fluxes (q glu , q ATP ) under the two E h7 conditions accompanied by the decrease of Y X/S and Y ATP suggested the existence of an uncoupling phenomenon, namely that some catabolized glucose and hence ATP was not associated with biomass production. Significance and Impact of the Study: This paper demonstrates the usefulness of taking into account, the effect of the oxidoreduction potential on the growth of Leuc. mesenteroides in the fermentation process.

Novel Redox Potential-Based Screening Strategy for Rapid Isolation of Klebsiella pneumoniae Mutants with Enhanced 1,3-Propanediol-Producing Capability

“…The preferred ORP range of the mutant shifted from around Ϫ190 mV to Ϫ280 mV (Fig. 5), suggesting not only different species or strains (7,30,31) but also that the mutants of the same strain had significantly different preferred ORP ranges. In comparison with the parent strain, the highest cell concentration and 1,3-PD production of the mutant strain were enhanced by 68.0% and 63.1%, respectively.…”

“…The parameter that we used to develop this screening approach was redox potential (oxidoreduction potential [ORP]). Recently, ORP has been used as a parameter to investigate mass and energy metabolic fluxes in several microorganisms (7,26,30). It has been reported that each species, or even each strain, has a preferred redox potential range.…”

Metabolic Changes in Klebsiella oxytoca in Response to Low Oxidoreduction Potential, as Revealed by Comparative Proteomic Profiling Integrated with Flux Balance Analysis

“…Decreased ORP levels also improved the xylitol yield of stationary-phase fermentation by Candida tropicalis (19). Therefore, the extracellular ORP is a useful parameter for monitoring and regulating microbial metabolism in anaerobic or microaerobic processes (4,12,13,(19)(20)(21)(22)24).However, the physiological response of microbial cells to ORP alterations remains unclear. ORP changes may affect cellular physiology by altering intracellular redox levels (4), affecting the expression of individual enzymes (16,25) and changing the oxidative states of protein thiol groups.…”

“…The ORP quantifies the redox property of solutions (11) and is a primary affecter of (facultative) anaerobic growth and metabolism (4,(12)(13)(14)(15)(16)(17). Generally, each microbial species optimally grows within a certain ORP range (14-16), and alteration of extracellular ORP usually leads to metabolic flux redistribution.…”

“…Decreased ORP levels also improved the xylitol yield of stationary-phase fermentation by Candida tropicalis (19). Therefore, the extracellular ORP is a useful parameter for monitoring and regulating microbial metabolism in anaerobic or microaerobic processes (4,12,13,(19)(20)(21)(22)24).…”