Physiological mechanism of improved tolerance of Saccharomyces cerevisiae to lignin-derived phenolic acids in lignocellulosic ethanol fermentation by short-term adaptation

Table 2 Concentrations of combined phenolic acids in synthetic media

	Concentrations of phenolic acids in adaptation media (g/L)
	Vanillic acid	p-hydroxybenzoic acid	Syringic acid
IC25^a	1.16	0.70	0.58
IC50	1.40	0.84	0.70
IC75	1.60	0.97	0.80
IC100	1.90	1.14	0.95

^aIC25, IC50, IC75 and IC100 represented the synthetic media contained phenolic acids at inhibitory concentrations which could cause 25%, 50%, 75% and 100% inhibition on growth rate of the parental strain. The concentration of vanillic acid, p-hydroxybenzoic acid and syringic acid in the original mixture of phenolic acids was 2.5, 1.5 and 1.25 g/L and gradually diluted to different concentration level with the constant ratio shown as Table 1. A fitting curve of growth inhibition rate (GI) and dilution times was established based on the data of Table 1. The concentration of phenolic acids mixture led to 25%, 50% or 75% of growth inhibition was obtained by putting the growth inhibition rate of 25%, 50% and 75% into the equation of the fitting curve, respectively, and calculated the corresponding dilution times

ISSN: 2731-3654