In this work, Saccharomyces cerevisiae strains PE-2 and CAT-1, commonly used in the Brazilian fuel ethanol industry, were engineered for xylose fermentation, where the first fermented xylose faster than the latter, but also produced considerable amounts of xylitol. An engineered PE-2 strain (MEC1121) efficiently consumed xylose in presence of inhibitors both in synthetic and corn-cob hydrolysates. Interestingly, the S. cerevisiae MEC1121 consumed xylose and glucose simultaneously, while a CEN.PK based strain consumed glucose and xylose sequentially. Deletion of the aldose reductase GRE3 lowered xylitol production to undetectable levels and increased xylose consumption rate which led to higher final ethanol concentrations. Fermentation of corn-cob hydrolysate using this strain, MEC1133, resulted in an ethanol yield of 0.47 g/g of total sugars which is 92% of the theoretical yield.

During the co-translational assembly of protein complexes, a fully synthesized subunit engages with the nascent chain of a newly synthesized interaction partner. Such events are thought to contribute to productive assembly, but their exact physiological relevance remains underexplored. Here, we examine structural motifs contained in nucleoporins for their potential to facilitate co-translational assembly. We experimentally test candidate structural motifs and identify several previously unknown co-translational interactions. We demonstrate by selective ribosome profiling that domain invasion motifs of beta-propellers, coiled-coils, and short linear motifs may act as co-translational assembly domains. Such motifs are often contained in proteins that are members of multiple complexes (moonlighters) and engage with closely related paralogs. Surprisingly, moonlighters and paralogs assemble co-translationally in only some but not all of the relevant biogenesis pathways. Our results highlight the regulatory complexity of assembly pathways.

Dissolution of CO 2 in water was studied for a batch vertical multiorifice baffled column (MOBC) with varying orifice diameters (d 0 ) of 6.4−30 mm and baffle open area (α) of 15−42%. Bubble size distributions (BSDs) and the overall volumetric CO 2 mass transfer coefficient (K L a) were experimentally evaluated for very low superficial gas velocities, U G of 0.12− 0.81 mm s −1 , using 5% v/v CO 2 in the inlet gas stream at a range of fluid oscillations (f = 0−10 Hz and x 0 = 0−10 mm). Remarkably, baffles presenting large d o = 30 mm and α = 36%, therefore in the range typically found for single-orifice oscillatory baffled columns, were outperformed with respect to BSD control and CO 2 dissolution by the other baffle designs or the same aerated column operating without baffles or fluid oscillations. Flow visualization and bubble tracking experiments also presented in this study established that a small d o of 10.5 mm combined with a small value of α = 15% generates sufficient, strong eddy mixing capable of generating and trapping an extremely large fraction of microbubbles in the MOBC. This resulted in increased interfacial area yielding K L a values up to 65 ± 12 h −1 in the range of the U G tested, representing up to 3-fold increase in the rate of CO 2 dissolution when compared to the unbaffled, steady column. In addition, a modified oscillatory Reynolds number, Re o ′ and Strouhal number, St′ were presented to assist on the design and scale-up of gas−liquid systems based on multiorifice oscillatory baffled columns. This work is relevant to gas−liquid or multiphase chemical and biological systems relying on efficient dissolution of gaseous compounds into a liquid medium.