Conversion of
            <scp>l</scp>
            -Leucine to Isovaleric Acid by
            <i>Propionibacterium freudenreichii</i>
            TL 34 and ITGP23

Thierry, Anne; Maillard, Marie-Bernadette; Yvon, Mireille

doi:10.1128/aem.68.2.608-615.2002

Cited by 93 publications

(76 citation statements)

References 46 publications

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“…This finding was verified with two other strains of each species. L. helveticus mainly produced phenylacetic acid from Phe and isovaleric acid from Leu, as previously observed for propionibacteria (21), while L. delbrueckii subsp. lactis produced large amounts of alcohols (and/or aldehydes).…”

supporting

confidence: 55%

“…lactis, and Streptococcus thermophilus. Recently, Thierry et al have shown that propionibacteria are capable of producing isovaleric acid from leucine in vitro (21) and are mainly responsible for its production in Swiss cheese (22). However, propionibacteria do not seem to be capable of producing aldehydes from amino acids, while these compounds are very important for Swiss cheese aroma.…”

mentioning

confidence: 99%

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Ability of Thermophilic Lactic Acid Bacteria To Produce Aroma Compounds from Amino Acids

Hélinck

Bars

Moreau³

et al. 2004

Appl Environ Microbiol

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105

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Although a large number of key odorants of Swiss-type cheese result from amino acid catabolism, the amino acid catabolic pathways in the bacteria present in these cheeses are not well known. In this study, we compared the in vitro abilities of Lactobacillus delbrueckii subsp. lactis, Lactobacillus helveticus, and Streptococcus thermophilus to produce aroma compounds from three amino acids, leucine, phenylalanine, and methionine, under mid-pH conditions of cheese ripening (pH 5.5), and we investigated the catabolic pathways used by these bacteria. In the three lactic acid bacterial species, amino acid catabolism was initiated by a transamination step, which requires the presence of an ␣-keto acid such as ␣-ketoglutarate (␣-KG) as the amino group acceptor, and produced ␣-keto acids. Only S. thermophilus exhibited glutamate dehydrogenase activity, which produces ␣-KG from glutamate, and consequently only S. thermophilus was capable of catabolizing amino acids in the reaction medium without ␣-KG addition. In the presence of ␣-KG, lactobacilli produced much more varied aroma compounds such as acids, aldehydes, and alcohols than S. thermophilus, which mainly produced ␣-keto acids and a small amount of hydroxy acids and acids. L. helveticus mainly produced acids from phenylalanine and leucine, while L. delbrueckii subsp. lactis produced larger amounts of alcohols and/or aldehydes. Formation of aldehydes, alcohols, and acids from ␣-keto acids by L. delbrueckii subsp. lactis mainly results from the action of an ␣-keto acid decarboxylase, which produces aldehydes that are then oxidized or reduced to acids or alcohols. In contrast, the enzyme involved in the ␣-keto acid conversion to acids in L. helveticus and S. thermophilus is an ␣-keto acid dehydrogenase that produces acyl coenzymes A.Amino acid catabolism by the microflora is a major process for the formation of a large number of key aroma compounds in Swiss-type cheeses such as gruyere and emmental (7,14,17). However, the amino acid catabolic pathways in the different bacteria present in these cheeses are not well known. This knowledge could lead to the development of cultures with optimized aromatic properties.Amino acid catabolism by Lactococcus lactis and mesophilic lactobacilli has been extensively studied recently (2,8,11,19,26; S. Gummalla and J. R. Broadbent, Abstract, J. Dairy Sci. 79(Suppl.

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supporting

confidence: 55%

mentioning

confidence: 99%

Ability of Thermophilic Lactic Acid Bacteria To Produce Aroma Compounds from Amino Acids

Hélinck

Bars

Moreau³

et al. 2004

Appl Environ Microbiol

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105

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“…High amounts of isocaproic acid were also produced by half of the tested strains of P. thoenii, P. jensenii and P. acidipropionici. The kinetics of isovaleric acid production was determined in YEL medium for two P. freudenreichii strains: it was produced throughout growth, concomitantly with lactate fermentation [59]. After lactate exhaustion, growth stopped while isovaleric acid further increased.…”

Section: Production Of Volatile Compounds In Culture Mediummentioning

confidence: 99%

Production of cheese flavour compounds derived from amino acid catabolism by Propionibacterium freudenreichii

Thierry

Maillard

2002

Lait

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-The catabolism of amino acids by cheese micro-organisms results in the production of various volatile flavour compounds. It was recently shown to be a rate-limiting factor in the formation of cheese flavour, leading to an increased interest in elucidating the pathways and the flora involved. This paper reviews the ability of propionibacteria (PAB) to produce flavour compounds deriving from branched-chain, aromatic and sulphur-containing amino acids. In culture media, PAB produced volatile compounds derived from Leu, Ile, Met and Phe. In cheese, the presence of PAB is positively correlated to the amount of acids, alcohols and/or aldehydes derived from Leu or Ile. The metabolic pathways of amino acid conversion to flavour compounds by PAB have been only partly elucidated. Aminotransferase(s) catalyse the first step of conversion of branched-chain, aromatic amino acids and methionine, with a higher activity for branched-chain amino acids. The α-keto acids resulting from transamination are further degraded to various compounds by resting cells of PAB. So α-ketoisocaproic acid, derived from Leu, is essentially converted to isovaleric acid by a ketoacid dehydrogenase complex; phenylpyruvic acid, derived from Phe, is converted to phenyllactic acid, phenylacetic acid, benzoic acid and benzaldehyde. Methionine can also be directly degraded by α, γ -elimination, leading to methanethiol. The amino acid catabolism pathways in PAB share similarities with those of lactic acid bacteria but PAB seem to produce higher amounts of branched-chain acids, which are important flavour compounds in cheese.propionibacteria / flavour compound / amino acid / catabolism / cheese ripening Résumé -Production de composés d'arôme du fromage issus du catabolisme des acides aminés par Propionibacterium freudenreichii. Le catabolisme des acides aminés par les micro-organismes du fromage entraîne la formation de composés volatils variés. C'est une étape limitante de la formation de la flaveur du fromage, et les recherches visant à déterminer les voies métaboliques et les flores impliquées se sont récemment multipliées. Cette revue fait le point sur le catabolisme des acides aminés en composés d'arôme chez les bactéries propioniques (PAB). Les PAB sont impliquées dans la formation des composés volatils dérivant de Leu, Ile, Phe et Met, par des voies métaboliques qui ne sont que partiellement connues. La première étape de conversion des acides aminés ramifiés, aromatiques et de la méthionine est catalysée par une(des) aminotransférase(s). Les cétoacides résul-tant de la transamination sont ensuite dégradés en différents composés. Ainsi, l'acide α-cétoisoca-proïque, issu de Leu, est pour l'essentiel converti en acide isovalérique par un complexe cétoacide déshydrogénase ; l'acide phénylpyruvique, issu de Phe, est converti en acide phényllactique, acide phénylacétique, acide benzoïque et benzaldéhyde. La méthionine peut également être directement dégradée par α, γ -élimination, formant du méthanethiol. Ces voies cataboliques présentent des si...

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“…As both BC alcohols and BC aldehydes can be converted to their corresponding BC acids by cheese bacteria [44,51], they probably constitute only transitory compounds in Swiss cheese. BC aldehydes are characterised by their malty flavour, and 3-methylbutanal is considered as an odorant in Swiss cheese [33,34].…”

mentioning

confidence: 99%

Propionibacterium freudenreichii strains quantitatively affect production of volatile compounds in Swiss cheese

Thierry¹,

Maillard²,

Richoux

et al. 2005

Lait

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-Cheese flavour is the result of a complex mixture of volatile compounds, originating mainly from the enzymatic degradation of curd components by cheese microflora during cheese ripening. Directing cheese flavour development requires knowledge on inter-and intra-species contributions to flavour development, i.e. identification of the volatile (flavour) compounds produced by each strain. The aim of this study was to identify the volatile compounds produced in Swiss cheese by Propionibacterium freudenreichii, one of the species essential for the development of the characteristic flavour of this type of cheese. The volatile profile of compounds obtained from smallscale (1/100) Swiss cheeses, with or without P. freudenreichii, were compared (three strains tested, in association with three thermophilic lactic starters, i.e. twelve cheeses, manufactured in duplicate). Neutral volatile compounds, extracted by dynamic headspace, and free fatty acids were identified using gas chromatography-mass spectrometry. The concentrations of all carboxylic acids and 14 of 58 neutral compounds were significantly higher in the presence of propionibacteria (PAB). The three PAB strains tested produced the same volatile compounds, but observed quantitative differences were strain-dependent. Propionic acid and four propionate esters were detected only in the presence of PAB. Moreover, cheeses with PAB contained two-to three-fold higher levels of free fatty acids derived from lipolysis and five-to fifty-fold higher levels of branched-chain compounds derived from isoleucine catabolism (2-methylbutanal, 2-methylbutanol and 2-methylbutanoic acid) and from leucine catabolism (3-methylbutanoic acid). Lactic starters induced significant variations in the concentrations of some of the compounds produced by PAB, such as methylbutanoic acids and free fatty acids, which varied by 2.0 and 1.4, respectively, as a function of the lactobacilli strains. PAB strains affect the concentration of varied volatile compounds and could therefore have distinct contributions to the formation of Swiss cheese flavour.

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Conversion of l -Leucine to Isovaleric Acid by Propionibacterium freudenreichii TL 34 and ITGP23

Cited by 93 publications

References 46 publications

Ability of Thermophilic Lactic Acid Bacteria To Produce Aroma Compounds from Amino Acids

Ability of Thermophilic Lactic Acid Bacteria To Produce Aroma Compounds from Amino Acids

Production of cheese flavour compounds derived from amino acid catabolism by Propionibacterium freudenreichii

Propionibacterium freudenreichii strains quantitatively affect production of volatile compounds in Swiss cheese

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