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1.
J Agric Food Chem ; 57(22): 10664-9, 2009 Nov 25.
Article in English | MEDLINE | ID: mdl-19919115

ABSTRACT

The aim of this work was to investigate if contaminating microorganisms, eventually present in bacteria and yeast preparations used as commercial starters in winemaking, have the ability to produce the biogenic amines histamine, putrescine and tyramine. Thirty commercial starters (14 yeasts Saccharomyces cerevisiae and 16 bacteria Oenococcus oeni) were cultured in synthetic broth and analyzed by TLC to detect amine production. Oenococcus oeni commercial preparations did not contain contaminants, but some yeast preparations resulted contaminated with amine-producing bacteria. Bacterial contaminants were isolated and analyzed for their ability to produce biogenic amines using HPLC and TLC. Decarboxylase genes were identified using PCR analysis followed by sequencing. Fermentations were performed in grape juice with two yeast commercial preparations containing bacterial contaminants to check if the potential biogenic amine production could happen also during winemaking. It was found that this production is possible; in particular, in the conditions used in this work, tyramine production was detected. Therefore, the results of this study have significance in relation to the risk of biogenic amines in wine. Moreover a novel species of Lactobacillus was found to be able to produce histamine.


Subject(s)
Bacteria/metabolism , Biogenic Amines/biosynthesis , Wine/microbiology , Carboxy-Lyases/genetics , Chromatography, High Pressure Liquid , Chromatography, Thin Layer , DNA, Bacterial/analysis , Fermentation , Histamine/biosynthesis , Polymerase Chain Reaction , Putrescine/biosynthesis , Tyramine/biosynthesis , Wine/analysis
2.
Int J Food Microbiol ; 129(1): 30-6, 2009 Jan 31.
Article in English | MEDLINE | ID: mdl-19062120

ABSTRACT

During the industrial production of active dry yeast (ADY) and its subsequent use in winemaking, the yeast cell is subjected to drastic environmental changes that force it to undergo extensive metabolic modifications and changes in gene expression. In this study, we describe the use of real-time reverse transcription-polymerase chain reaction (RT-PCR) to monitor gene expression in ADY Saccharomyces cerevisiae during rehydration in different media. We used three statistical approaches to investigate the expression stability of eight potential reference genes during the rehydration process. The reference system thus obtained was used to normalize the expression values of three genes codifying for the ammonium transporters -- MEP1, MEP2, and MEP3 -- and two genes involved in the osmotic response-SIP18 and GPD1. The results suggested that for the target genes tested, the yeast reacted immediately to rehydration only when a fermentable carbon source was present in the medium. Furthermore, MEP2 expression was modulated by the ammonium concentration, indicating that nitrogen catabolite repression (NCR) is active during the rehydration phase.


Subject(s)
Energy Metabolism/genetics , Genes, Fungal/genetics , Genes, Fungal/physiology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Water/pharmacology , Culture Media/chemistry , Gene Expression Profiling , Gene Expression Regulation, Fungal , Industrial Microbiology , Osmotic Pressure , Quaternary Ammonium Compounds/metabolism , Quaternary Ammonium Compounds/pharmacology , Reverse Transcriptase Polymerase Chain Reaction , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolism
3.
J Food Prot ; 70(9): 2155-60, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17900096

ABSTRACT

A study was carried out to determine the in vitro interaction between ochratoxin A (OTA) and wine lactic acid bacteria (LAB). Fifteen strains belonging to five relevant oenological LAB species were grown in liquid synthetic culture medium containing OTA. The portion of OTA removed during the bacterial growth was 8 to 28%. The OTA removed from the supernatants was partially recovered (31 to 57%) from the bacterial pellet. Cell-free extracts of three representative strains were produced by disrupting cells in a French pressure cell. The ability of crude cell-free extracts to degrade OTA was studied. OTA was not degraded by cell-free extracts of wine LAB strains, and no degradation products of OTA were detected in the high-performance liquid chromatograms of the methanol extract of the bacterial pellet. On the basis of these results, we conclude that OTA removal by wine LAB is a cell-binding phenomenon. The chemistry and the molecular basis of OTA binding to wine LAB remains unknown.


Subject(s)
Decontamination/methods , Food Contamination/analysis , Lactobacillus/physiology , Ochratoxins/analysis , Wine , Humans , Industrial Microbiology/methods , Lactobacillus/metabolism , Vitis/chemistry , Wine/analysis , Wine/microbiology
4.
J Food Prot ; 69(2): 391-6, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16496581

ABSTRACT

Biogenic amines are frequently found in wine and other fermented food. We investigated the ability of 133 strains of lactic acid bacteria isolated from musts and wines of different origins to produce histamine, tyramine, and putrescine. We detected the genes responsible for encoding the corresponding amino acid decarboxylases through PCR assays using two primer sets for every gene: histidine decarboxylase (hdc), tyrosine decarboxylase (tdc), and ornithine decarboxylase (odc); these primers were taken from the literature or designed by us. Only one strain of Lactobacillus hilgardii was shown to possess the hdc gene, whereas four strains of Lactobacillus brevis had the tdc gene. None of the Oenococcus oeni strains, the main agents of malolactic fermentation, was a biogenic amine producer. All PCR amplicon band-positive results were confirmed by thin-layer chromatography and high-performance liquid chromatography analyses.


Subject(s)
Biogenic Amines/biosynthesis , Food Microbiology , Lactobacillus , Vitis/microbiology , Wine/microbiology , Base Sequence , Biogenic Amines/analysis , Chromatography, High Pressure Liquid/methods , Chromatography, Thin Layer/methods , Fermentation , Histamine/analysis , Histamine/biosynthesis , Lactobacillus/classification , Lactobacillus/genetics , Lactobacillus/isolation & purification , Lactobacillus/metabolism , Polymerase Chain Reaction/methods , Putrescine/analysis , Putrescine/biosynthesis , Sequence Alignment , Tyramine/analysis , Tyramine/biosynthesis
5.
J Agric Food Chem ; 52(7): 1861-6, 2004 Apr 07.
Article in English | MEDLINE | ID: mdl-15053521

ABSTRACT

In wine making, the bacteriolytic activity of lysozyme has primarily been used to control the malolactic fermentation in wines. The use of lysozyme in musts before settling and the beginning of the alcoholic fermentation to inhibit the growth of lactic acid bacteria could be very beneficial. In a resistance test carried out in MT/b broth, lysozyme had greater antimicrobial activity toward Oenococcus oeni than Lactobacillus species. Several strains of wine bacteria belonging to Oenococcus proved sensitive to the bacteriolytic activity of lysozyme at low concentrations in both synthetic medium (MT/b) (50 mg/L), white must, or red must made with or without the skins (100 mg/L). Lactobacillus and Pediococcus strains survived at lysozyme concentrations of 200-500 and 500 mg/L, respectively, in MT/b and musts. Suspended solids in unclarified musts may strongly bind to lysozyme thereby causing its removal by filtration or centrifugation. One hour after lysozyme was added to musts, it was quantified by HPLC and found after centrifugation to be 40-50% and only 10% in musts made with or without the skins, respectively. Although appreciable amounts of lysozyme were bound to wine components, this did not appear to be a serious hindrance to lysozyme activity.


Subject(s)
Fruit/enzymology , Muramidase/metabolism , Vitis/enzymology , Wine/microbiology , Enzyme Stability , Fermentation , Lactobacillaceae/metabolism , Lactobacillus/metabolism , Pediococcus/metabolism
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