Effect of Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process

Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was <30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was >53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.

Synthesis and Crystal Structure of 3-(Pyrrole-2′-carboxamido)propanoic Acid·(1/2)H_(2)O

3-(Pyrrole-2?-carboxamido)propanoic acid I has been synthesized from the reaction of β-alanine methyl ester with 2-trichloroacetylpyrrole followed by saponifying and acidating in 85.4% yield, and the crystal structure of 3-(pyrrole-2?-carboxamido)propanoic acid· (1/2)H2O (C8H11N2O3.5, Mr = 191.19) was obtained and determined by X-ray diffraction method. The crystal is of monoclinic, space group C2/c with a = 19.010(4), b = 8.3515(17), c = 13.788(3) ?, β = 125.88(3)o, V = 1773.6(6) ?3, Z = 8, Dc = 1.432 g/cm3, λ = 0.71073 ?, μ(MoKα) = 0.114 mm?1 and F(000) = 768. The structure was refined to R = 0.0354 and wR = 0.0942 for 1642 observed reflections with I > 2σ(I). It is revealed that the title compound has one pyrrole ring and one propionic acid subchain linked by an amido bond at C(4), and there are 8 molecules of com- pound I and 4 crystal water molecules in each unit cell. The supramolecular layers are stabilized by the hydrogen bonds of N(2) H…O(2), N(1) H…O(4), O(4) H(1W)…O(2) and O(3) H…O(1).

Synthesis, Characterization and the Effect of Glucose-lowering of Guanidino Acid Oxovanadium(Ⅳ) Complexes

Two guanidino acid oxovanadium(IV) complexes have been synthesized. Preliminary tests in vivo have shown that the two title complexes all display lowering glucose activity in vivo to STZ-rats. The effect of glucose-lowering of guanidino acetic acid oxovanadium(IV) complex in vivo is higher than that of guanidino propanoic acid oxovanadium(IV) complex.

Metabolic diversification of anaerobic methanotrophic archaea in a deep-sea cold seep

Anaerobic methanotrophic archaea(ANME)can assimilate methane and govern the greenhouse effect of deep-sea cold seeps.In this study,a total of 13 ANME draft genomes representing five ANME types(ANME-la,ANME-lb,ANME-2a,ANME-2b and ANME-2c),in size between 0.8 and 1.8 Mbp,were obtained from the Jiaolong cold seep in the South China Sea.The small metagenome-assembled genomes(MAGs)contained all the essential pathways for methane oxidization and carbon dioxide fixation.All genes related to nitrate and sulfate reduction were absent from the MAGs,indicating their syntrophic dependence on partner organisms.Aside from acetate secretion and sugar storage,propanoate synthesis pathway,as an alternative novel carbon flow,was identified in all the MAGs and transcriptionally active.Regarding type-specific features of the MAGs,the genes encoding archaellum and bacteria-derived chemotaxis were specific to ANME-2,perhaps for fitness under fluctuation of methane and sulfate concentration flux.Our genomic and transcriptomic results strongly suggested that ANME could carry out simple carbon metabolism from Cl assimilation to C3 biosynthesis in the SCS cold seep,which casts light on a novel approach for synthetic biology.