Dalsgaardhaslund8273

The above is explained by the fact that only gadD2 transcription was upregulated by these compounds while the transcription of gadD1 and gadD3 remained unaffected. Together our results show that the L. monocytogenes GadD2 decarboxylase is activated in the presence of amino acids or peptides other than glutamate, a finding that has important implications for acid tolerance and food safety. This study was aimed to evaluate the effectiveness of two lactic acid bacteria (LAB) cultures (Lactococcus lactis FT27 and Carnobacteroim divergens SCA), lactic acid/sodium lactate (LASL - l-lactic acid 61% (w/w) and L-sodium lactate 21% (w/w)) and their combination against four Listeria monocytogenes biotypes isolated from Gorgonzola cheese. In vitro antilisterial activity showed that the sensitivity to antimicrobials was strain-dependent. Antimicrobial challenge testing was performed on Gorgonzola rinds simulating contamination occurring at the beginning (6 days) and at the end (55 days) of the ripening period, to assess the antilisterial activity of LAB strains and LASL during the subsequent 60 days at 4 °C. LASL showed a higher antilisterial activity than LAB, maintaining the pathogen content below the EC limit ( less then 2.0 log10 CFU/g) for 60 days. A strong listericidal effect was observed combining LAB with LASL (2,8 μL/cm2) Lc. lactis in combination with LASL completely inhibited the two L. monocytogenes strains in the first 50 days, while LASL with C. divergens was more effective in the second part of ripening when the pH raised. Data obtained encourage the use of LASL along with antimicrobial LAB rotation schemes during cheese ripening for the prevention and/or control of the L. monocytogenes on cheese surface. The suitability of forty-one non-Lactobacillus strains to be used as selected starters for sourdough fermentation was evaluated. According to the data collected, Pediococcus pentosaceus OA1 and S3N3 and Leuconostoc citreum PRO17 were selected based on the optimal acidification and growth performances and the intense proteolytic activity (increase of TFFA up to 80%) on whole wheat flour doughs. A relevant degradation of phytic acid (up to 58%) and the increase of phenols content and scavenging activity (4- and 2-folds, respectively) were also observed. The technological performances were compared to two representative Lactobacillus strains (Lactobacillus plantarum and Lactobacillus sanfranciscensis). The investigation of the robustness of the selected strains during the propagation (back-slopping procedure) showed their long-term dominance only when singly-inoculated; while Leuc. citreum PRO17 dominated the fermentation when the strains were co-inoculated. The sourdoughs obtained by the non-Lactobacillus selected strains (singly or pooled) were used for breadmaking. Selected sourdoughs allowed the production of breads characterized by in-vitro protein digestibility (IVPD) higher than that of breads obtained with Lactobacillus strains or baker's yeast. The aroma profile, estimated by GC/MS, was complex and characterized by high concentration of the typical compounds (hexanol, 3-methylbutanol and 2-pentylfuran) of sourdough bread. Hong Qu glutinous rice wine (HQGRW) is typically very bitter after fermentation due to the presence of bitter amino acids (BAA). The amino acids are considered to primarily derive from the hydrolysis of protein from the raw material by microbial populations during fermentation, and temperature also has an important effect on bitter tastes. Here, the dynamics of fungal and bacterial communities during the traditional fermentation of HQGRW were investigated using high-throughput sequencing and RNA-based rRNA gene sequencing. BMS-935177 concentration Both principal component analysis (PCA) and hierarchical clustering analysis (HCA) revealed significant differences between the fungal and bacterial communities during fermentation at 20 °C and those performed at 25 °C and 30 °C. The growth of Saccharomyces and some LAB apparently inhibited the growth of several pernicious bacterial taxa including acetic acid bacteria. The amino acid contents of the samples all increased continuously under the different temperature conditions. Moreover, higher temperatures were associated with higher perceptual intensity of bitterness and contents of amino acids including bitter, sweet, umami, and astringent type amino acids as well as the total amino acid content during fermentation. Furthermore, the total BAA content was strongly and positively correlated with Pediococcus, Saccharomyces, Lactobacillus, Monascus, and Halomonas relative abundances, with correlations identified by |r| > 0.6 with P adjusted P  less then  0.05. In conclusion, these results contribute to a better understanding of the mechanisms underlying BAA production during the traditional fermentation of HQGRW and will help improve the quality and safety of these wines. In this study, we presented the first metabolome time course analysis performed among a set of S. uvarum, S. kudriavzevii and S. cerevisiae strains under winemaking conditions. Extracellular and intracellular metabolites, as well as physiological parameters of yeast cells, were monitored along the process to find evidence of different metabolic strategies among species to perform alcoholic fermentation. A thorough inspection of time trends revealed several differences in utilization or accumulation of fermentation by-products. We confirmed the ability of S. uvarum and S. kudriavzevii strains to produce higher amounts of glycerol, succinate or some fusel alcohols and their corresponding esters. We also reported differences in the yields of less common fermentative by-products involved in redox homeostasis, namely 2,3 butanediol and erythritol. 2,3 butanediol yield was higher in must ferment with cryophilic strains and erythritol, a pentose phosphate pathway derivative, was particularly overproduced by S. uvarum strains. Contrary to S. cerevisiae, a singular production-consumption rate of acetate was also observed in S. uvarum and S. kudriavzevii fermentations. Since acetate is a precursor for acetyl-CoA production which is involved in the biosynthesis of membrane lipids, cryophilc strains might take advantage of extracellular acetate to remodel cell membrane as ethanol content increased during fermentation.