scholarly journals Melatonin in yeast and fermented beverages: analytical tools for detection, physiological role and biosynthesis

2020 ◽  
Vol 3 (2) ◽  
pp. 144-160 ◽  
Author(s):  
Sara Muñiz-Calvo ◽  
Ricardo Bisquert ◽  
José M. Guillamón
Keyword(s):  
Biosynthetic Pathway ◽  
Physiological Role ◽  
Aromatic Amino Acids ◽  
Bioactive Molecules ◽  
Research Topics ◽  
Fermented Beverages ◽  
Potential Benefits ◽  
Analytical Tools ◽  
Melatonin Production

The recently established relation between the metabolism of aromatic amino acids of yeast and the production of different bioactive molecules during fermentation opens up new and interesting research topics. Among these molecules, melatonin has drawn researchers’ attention in the last decade given its potential benefits for human health. This review summarizes melatonin production in fermented beverages, and conventional and current methods for detecting melatonin in yeast-derived samples. In addition, the role of melatonin in yeast is discussed and the biosynthetic pathway of melatonin is presented in Saccharomyces cerevisiae.

scholarly journals Disruption of the alsSD operon of Enterococcus faecalis impairs growth on pyruvate at low pH

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2708-2719 ◽  
Author(s):  
Guillermo D. Repizo ◽  
Pablo Mortera ◽  
Christian Magni
Keyword(s):  
Enterococcus Faecalis ◽  
Mutant Strain ◽  
Biosynthetic Pathway ◽  
Growth Parameters ◽  
Physiological Role ◽  
Acetolactate Synthase ◽  
Low Ph ◽  
Transcriptional Analysis ◽  
Initial Ph

Diacetyl and acetoin are pyruvate-derived metabolites excreted by many micro-organisms, and are important in their physiology. Although generation of these four-carbon (C4) compounds in Enterococcus faecalis is a well-documented phenotype, little is known about the gene regulation of their biosynthetic pathway and the physiological role of the pathway in this bacterium. In this work, we identified the genes involved in C4 compound biosynthesis in Ent. faecalis and report their transcriptional analysis. These genes are part of the alsSD bicistronic operon, which encodes α-acetolactate synthase (AlsS) and α-acetolactate decarboxylase (AlsD). Our studies showed that alsSD operon transcription levels are maximal during the exponential phase of growth, decreasing thereafter. Furthermore, we found that this transcription is enhanced upon addition of pyruvate to the growth medium. In order to study the functional role of the alsSD operon, an isogenic alsSD mutant strain was constructed. This strain lost its capacity to generate C4 compounds, confirming the role of alsSD genes in this metabolic pathway. In contrast to the wild-type strain, the alsSD-deficient strain was unable to grow in LB medium supplemented with pyruvate at an initial pH of 4.5. This dramatic reduction in growth parameters for the mutant strain was simultaneously accompanied by the inability to alkalinize the internal and external medium under these conditions. In sum, these results suggest that the decarboxylation reactions related to the C4 biosynthetic pathway give enterococcal cells a competitive advantage during pyruvate metabolism at low pH.

scholarly journals Anthocyanins: Biosynthesis, Distribution, Ecological Role, and Use of Biostimulants to Increase Their Content in Plant Foods—A Review

Agriculture ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 212
Author(s):  
Giuseppe Mannino ◽  
Carla Gentile ◽  
Andrea Ertani ◽  
Graziella Serio ◽  
Cinzia Margherita Bertea
Keyword(s):  
Chemical Structure ◽  
Biosynthetic Pathway ◽  
Physiological Role ◽  
Plant Distribution ◽  
Anthocyanin Synthesis ◽  
Past Century ◽  
Anthocyanin Content ◽  
The Past ◽  
Increasing Demand

In the past century, plant biostimulants have been increasingly used in agriculture as innovative and sustainable practice. Plant biostimulants have been mainly investigated as potential agents able to mitigate abiotic stress. However, few information is available about their ability to influence fruit quality or change fruit phytochemical composition. In particular, very little is known about their effects on anthocyanin synthesis and accumulation. Due to the increasing demand of consumers for healthier foods with high nutraceutical values, this review tries to fill the gap between anthocyanin content and biostimulant application. Here, we elucidate the chemical structure, biosynthetic pathway, plant distribution, and physiological role of anthocyanins in plants. Moreover, we discuss the potential implications for human health derived from the consumption of foods rich in these molecules. Finally, we report on literature data concerning the changes in anthocyanin content and profile after the application of biostimulant products on the most common anthocyanin-containing foods.

Genetic Characterization of the Major Lactococcal Aromatic Aminotransferase and Its Involvement in Conversion of Amino Acids to Aroma Compounds

1999 ◽  
Vol 65 (11) ◽  
pp. 4873-4880 ◽  
Author(s):  
Liesbeth Rijnen ◽  
Sophie Bonneau ◽  
Mireille Yvon
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Physiological Role ◽  
Aromatic Amino Acids ◽  
Aroma Compounds ◽  
Gene Inactivation ◽  
Sequence Homologies ◽  
Branched Chain ◽  
Aromatic Aminotransferase

ABSTRACT In lactococci, transamination is the first step of the enzymatic conversion of aromatic and branched-chain amino acids to aroma compounds. In previous work we purified and biochemically characterized the major aromatic aminotransferase (AraT) of a Lactococcus lactis subsp. cremoris strain. Here we characterized the corresponding gene and evaluated the role of AraT in the biosynthesis of amino acids and in the conversion of amino acids to aroma compounds. Amino acid sequence homologies with other aminotransferases showed that the enzyme belongs to a new subclass of the aminotransferase I subfamily γ; AraT is the best-characterized representative of this new aromatic-amino-acid-specific subclass. We demonstrated that AraT plays a major role in the conversion of aromatic amino acids to aroma compounds, since gene inactivation almost completely prevented the degradation of these amino acids. It is also highly involved in methionine and leucine conversion. AraT also has a major physiological role in the biosynthesis of phenylalanine and tyrosine, since gene inactivation weakly slowed down growth on medium without phenylalanine and highly affected growth on every medium without tyrosine. However, another biosynthesis aromatic aminotransferase is induced in the absence of phenylalanine in the culture medium.

scholarly journals Ascorbic Acid and Ozone: Novel Perspectives to Explain an Elusive Relationship

Plants ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 122 ◽  
Author(s):  
Erika Bellini ◽  
Mario C. De Tullio
Keyword(s):  
Ascorbic Acid ◽  
Biosynthetic Pathway ◽  
Regulation Of Gene Expression ◽  
Physiological Role ◽  
Total Content ◽  
Huge Amount ◽  
Ozone Sensitivity ◽  
Ozone Tolerance ◽  
The Relationship

A huge amount of studies highlighted the importance of high ascorbic acid (AA) content in ozone tolerance, yet the relationship between them appears more complex than a simple direct correlation. Sometimes the connection is clear, for example, two Arabidopsis mutants defective in the main AA biosynthetic pathway (vtc mutants) were identified by means of their ozone sensitivity. However, some low-AA containing mutants are relatively tolerant, suggesting that AA location/availability could be more relevant than total content. A clear distinction should also be made between ozone tolerance obtained when AA content is increased by experimental supplementation (exogenous AA), and the physiological role of plant-synthesized AA (endogenous AA), whose amount is apparently subjected to tight regulation. Recent findings about the role of AA in signal transduction and epigenetic regulation of gene expression open new routes to further research.

Grape Seeds Extract as Brain Food: A Review

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Souad El Gengaihi ◽  
Doha H. Abou Baker
Keyword(s):  
Antioxidant Activities ◽  
Complex Mixture ◽  
Grape Seed Extract ◽  
Grape Seed ◽  
Seed Extract ◽  
Amyloid Peptide ◽  
Grape Seeds ◽  
Potential Benefits ◽  
Reduced Risk

Interest in the biological role of bioactive compounds present in medicinal herbs has increased over the last years. Of particular interest are plants that have an anti-Alzheimer activities. Several plants can be useful for Alzheimer (AD) management. Such as these which have anti-inflammatory activity, acetylcholinesterase (AChE) inhibitory action, antiapoptotic, slow the aggregation of amyloid peptide and antioxidant activities. Grape seed extract (GSE) is a complex mixture of several compounds, mostly represented by polyphenols and flavonoids. Their consumption is safe and is recognized to exert several health benefits. GS flavonoids have been associated with the reduced risk of chronic diseases, we present some findings on the potential benefits of GSE for the treatment of AD.

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow
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