Effects of acetic acid and lactic acid on the growth of Saccharomyces cerevisiae in a minimal medium

Abstract

Specific growth rates (mu) of two strains of Saccharomyces cerevisiae decreased exponentially (R2 > 0.9) as the concentrations of acetic acid or lactic acid were increased in minimal media at 30 degrees C. Moreover, the length of the lag phase of each growth curve (h) increased exponentially as increasing concentrations of acetic or lactic acid were added to the media. The minimum inhibitory concentration (MIC) of acetic acid for yeast growth was 0.6% w/v (100 mM) and that of lactic acid was 2.5% w/v (278 mM) for both strains of yeast. However, acetic acid at concentrations as low as 0.05-0.1% w/v and lactic acid at concentrations of 0.2-0.8% w/v begin to stress the yeasts as seen by reduced growth rates and decreased rates of glucose consumption and ethanol production as the concentration of acetic or lactic acid in the media was raised. In the presence of increasing acetic acid, all the glucose in the medium was eventually consumed even though the rates of consumption differed. However, this was not observed in the presence of increasing lactic acid where glucose consumption was extremely protracted even at a concentration of 0.6% w/v (66 mM). A response surface central composite design was used to evaluate the interaction between acetic and lactic acids on the specific growth rate of both yeast strains at 30 degrees C. The data were analysed using the General Linear Models (GLM) procedure. From the analysis, the interaction between acetic acid and lactic acid was statistically significant (P < or = 0.001), i.e., the inhibitory effect of the two acids present together in a medium is highly synergistic.

Microbial succession in a fermenting of wild forest noni (Morinda coreia Ham) fruit plus molasses and its role in producing a liquid fertilizer

“…It is well recognized that Pichia and Candida species are lactic acid-utilizing yeasts (Kitamoto et al 1999). This removal of lactic acid may have provided a positive stimulus to the proliferation of S. cerevisiae because it is sensitive to acetic acid and lactic acid (Narendranath et al 2001) and agrees with the results in this study where S. cerevisiae was present throughout the fermentation and also correlates with the high amount of ethanol in the FWE. However, some ethanol may be produced by P. anomala as previously mentioned and also the lactobacilli via the phosphoketolase pathway depending on the redox potential but unfortunately this was not measured in this study.…”

Ethanol Production from Hydrothermally-Treated Biomass from West Africa

“…Propionic acid was detected in very low levels, at a maximum of 0.067 g/100 g DM in raw elephant grass, while formic acid was detected only in raw wheat straw at 0.2 g/100 g DM. Lactic acid and acetic acid concentrations reached maximum values of 0.29 and 0.09% w/v for raw elephant grass and pretreated rubber, respectively; the levels were generally too low to inhibit yeast at the reaction conditions (Narendranath et al 2001;Graves et al 2006).…”

Qualidade pós-colheita de colmos de cana armazenados e seus reflexos na produção de cachaça

“…As bactérias láticas podem produzir ácido lático e acético, ocasionando inibição na taxa de crescimento específica das leveduras (NARENDRANATH et al, 2001) enquanto, linhagens de leveduras não Saccharomyces, também podem contribuir com a elevação dos níveis de ácido acético no caldo fermentado (DUARTE et al, 2013 Qualidade pós-colheita de colmos de cana armazenados e seus reflexos na produção de cachaça Oliveira Filho, J. H. et al 5° ciclo, em fermentações conduzidas com caldo de cana armazenada por 72 e 96 horas (Figura 4). A menor qualidade tecnológica do caldo associada ao crescimento de contaminantes no fermento reciclado são fatores que favorecem o comprometimento das leveduras no processo, reduzindo assim a assimilação dos substratos.…”