Inhibition effects of furfural on aerobic batch cultivation of Saccharomyces cerevisiae growing on ethanol and/or acetic acid

Physiological effects of furfural on Saccharomyces cerevisiae growing on ethanol (15 g.l(-1)) or acetate (20 g.l(-1)) as the carbon and energy source were investigated. Furfural (4 g.l(-1)), which was added during the exponential growth phase in batch cultures, was found to strongly inhibit cell growth on both carbon sources. No biomass formation occurred in the presence of furfural. However, furfural was in both cases converted to furfuryl alcohol and furoic acid, and growth resumed after complete conversion of furfural. During growth on ethanol, a rapid initial conversion of furfural to furfuryl alcohol was observed during the first few minutes after the addition of furfural, after which the conversion rate decreased to approximately 0.15 g.g(-1).h(-1) for the remaining conversion time. Acetaldehyde accumulated in the medium during the first few hours of conversion. Interestingly, addition of acetate after furfural addition resulted in an increased conversion rate of furfural and a higher carbon dioxide evolution rate, but no growth was observed until after complete conversion of furfural. Furfural addition to cells growing on acetate as the sole carbon source induced no formation of acetaldehyde, and the furfural conversion rate was lower than that on ethanol. The relationship between inhibition effects of furfural and NADH consumption is discussed.     

Improved Recovery of Stressed <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> from Frozen Foods

The Canadian reference method for the enumeration of Listeria monocytogenes (Health Canada method MFLP-74) was modified by the addition of a layer of non-selective tryptone soy agar (TSA) to the Oxford, Palcam, and (or) Rapid’L.mono selective agars, to improve the recovery of stressed L. monocytogenes from frozen foods. The performance of the standard selective agars versus the selective agars with an additional TSA agar layer (TAL agars) showed that for each of the frozen food items tested (vegetables, shrimp and meatballs), as well as for all data combined, L. monocytogenes counts were significantly higher (up to 20% higher) in TAL agars in relation to the standard agars (p < 0.0001, α = 0.05). A selectivity assessment showed that the 50 inclusivity L. monocytogenes strains tested produced true positive reactions on the TAL agars, and the 30 exclusivity bacterial strains tested produced true negative results on the TAL agars, indicating that the specificity of the selective agars was not altered by the additional non-selective TSA layer. In light of the 2016 Listeria outbreak linked to frozen fruits and vegetables in the USA, the results of this method investigation seem to be timely and particularly important for the regulatory testing of frozen foods.     

Front Cover: Development and Characterization of Selective FAK Inhibitors and PROTACs with In Vivo Activity (ChemBioChem 19/2023)

Focal adhesion kinase (FAK) is an attractive drug target due to its overexpression in cancer. FAK functions as a non-receptor tyrosine kinase and scaffolding protein, coordinating several downstream signaling effectors and cellular processes. While drug discovery efforts have largely focused on targeting FAK kinase activity, FAK inhibitors have failed to show efficacy as single agents in clinical trials. Here, using structure-guided design, we report the development of a selective FAK inhibitor (BSJ-04-175) and degrader (BSJ-04-146) to evaluate the consequences and advantages of abolishing all FAK activity in cancer models. BSJ-04-146 achieves rapid and potent FAK degradation with high proteome-wide specificity in cancer cells and induces durable degradation in mice. Compared to kinase inhibition, targeted degradation of FAK exhibits pronounced improved activity on downstream signaling and cancer cell viability and migration. Together, BSJ-04-175 and BSJ-04-146 are valuable chemical tools to dissect the specific consequences of targeting FAK through small-molecule inhibition or degradation.