Growth inhibition of S. cerevisiae, B. subtilis, and E. coli by lignocellulosic and fermentation products

Abstract

This paper describes the effect of several inhibiting components on three potential hosts for the bio-based production of methyl propionate, namely, wild-type Escherichia coli and Bacillus subtilis, and evolved Saccharomyces cerevisiae IMS0351. The inhibition by the lignocellulose-derived products 5-hydroxymethyl-2-furaldehyde, vanillin, and syringaldehyde and the fermentation products 2-butanol, 2-butanone, methyl propionate, and ethyl acetate has been assessed for these strains in defined medium. Multiple screenings were performed using small-scale cultures in both shake flasks and microtiter plates. Technical drawbacks revealed the limited applicability of the latter in this study. The microbial growth was characterized by means of a lag-time model, and the inhibitory thresholds were determined using product-inhibition models. The lignocellulose-derived products were found to be highly inhibitory, and none of the strains could grow in the presence of 2.0 g L−1 of product. From the fermentation products tested, methyl propionate had the most severe impact resulting in complete inhibition of all the strains when exposed to concentrations in the range of 12–18 g L−1. In general, S. cerevisiae and B. subtilis were comparatively more tolerant than E. coli to all the fermentation products, despite E. coli’s lower sensitivity towards vanillin. The results suggest that, overall, the strains investigated have good potential to be engineered and further established as hosts for the bio-based production of methyl esters.

The Protective Role of Intracellular Glutathione in Saccharomyces Cerevisiae During Lignocellulosic Ethanol Fermentation 

“…Another key observation in our work is that there is a threshold for tolerance as also reported by Pereira et al (Pereira et al 2016). When we conducted the SSF with 5% solids, all the strains yielded near identical response, but at 10% solids, differences clearly manifested.…”

Nectar‐inhabiting microorganisms influence nectar volatile composition and attractiveness to a generalist pollinator

“…Volatiles produced by nectar microbes are likely to be byproducts of microbial metabolism or fermentation, but may have diverse ecological functions. Nectar‐inhabiting microbes often suppress the growth of late‐arriving species in nectar (Peay et al ., ; Vannette & Fukami, ; Mittelbach et al ., ), and the volatiles ethyl acetate, 2‐butanol, isobutanol, ethanol, 2‐ethyl‐1‐hexanol and 2‐phenylethanol have been shown to inhibit microbial growth (Cruz et al ., ; Hua et al ., ; Pereira et al ., ). Alternatively, for microbes that rely on pollinator‐mediated phoresis, volatiles may be attractive or aid in dispersal.…”

Sweet Scents: Nectar Specialist Yeasts Enhance Nectar Attraction of a Generalist Aphid Parasitoid Without Affecting Survival

“…Volatiles produced by NIYs are mainly byproducts or secondary metabolites of the yeast metabolism or fermentation but may have diverse ecological functions (Dzialo et al, 2017 ). For example, volatile compounds such as ethyl acetate, 2-butanol, isobutanol, ethanol, 2-ethyl-1-hexanol and 2-phenylethanol have been shown to inhibit microbial growth (Cruz et al, 2012 ; Hua et al, 2014 ; Pereira et al, 2016 ), and may help explain why earlier nectar-colonizers often suppress the growth of later arriving microbial species (Peay et al, 2012 ; Vannette and Fukami, 2014 ). Furthermore, microbes that rely on insects for dispersal or survival may produce volatiles that are attractive to the insect vectors (Dzialo et al, 2017 ).…”