Carbon and nitrogen sources consumption by ale and lager yeast strains: a comparative study during fermentation.

The rapid and efficient consumption of carbon and nitrogen sources by brewer's yeast is critical for the fermentation process in the brewing industry. The comparison of the growth characterizations of typical ale and lager yeast, as well as their consumption preference to carbon and nitrogen sources were investigated in this study. Results showed that the ale strain grew faster and had a more extended stationary phase than the lager strain. However, the lager strain was more tolerant to the stressful environment in the later stage of fermentation. Meanwhile, the ale and lager yeast strains possessed varying preferences for metabolizing the specific fermentable sugar or free amino acid involved in the wort medium. The lager strain had a strong capacity to synthesize the extracellular invertase required for hydrolyzing sucrose as well as a strong capability to metabolize glucose and fructose. Furthermore, the lager strain had an advantage in consuming Lys, Arg, Val, and Phe, whereas the ale strain had a higher assimilation rate in consuming Tyr. These findings provide valuable insights into selecting the appropriate brewer's yeast strain based on the wort components for the industrial fermentation process. KEY POINTS: • The lager strain is more tolerant to the stressful environment. • The lager strain has the great capability to synthesize the extracellular invertase. • The assimilation efficiency of free amino acid varies between ale and lager.

Structural origins of two-dimensional elastic bending in a nonaromatic organic molecular crystal.

Mechanically flexible crystals are generally obtained based on weak interactions in the aromatic systems. Here, we reported the remarkable 2D elastic bending behaviors in a nonaromatic organic molecular crystal. The strong hydrogen bonding interactions are also verified to play a crucial role in the reversible bending.

Controllable fabrication of Pt nanocatalyst supported on N-doped carbon containing nickel nanoparticles for ethanol oxidation.

In this paper, platinum nanoparticles were deposited on a carbon carrier with the partly graphitized carbon and the highly dispersive carbon-coated nickel particles. An efficient electron transfer structure can be fabricated by controlling the contents of the deposited platinum. The high resolution transmission electron microscopy images of Pt2/Ni@CN-doped sample prove the electron transfer channel from Pt (1 1 1) crystal planes to graphite (1 0 0) or Ni (1 1 1) crystal planes due to these linked together crystal planes. The Pt3/Ni@CN-doped with low Pt contents cannot form the electron transfer structure and the Pt1/Ni@CN-doped with high Pt contents show an obvious aggregation of Pt nanoparticles. The electrochemical tests of all the catalysts show that the Pt2/Ni@CN-doped sample presents the highest catalytic activity, the strongest CO tolerance and the best catalytic stability. The high performance is attributed to the efficient electronic transport structure of the Pt2/Ni@CN-doped sample and the synergistic effect between Pt and Ni nanoparticles. This paper provides a promising method for enhancing the conductivity of electrode material.