Evaluation of the contribution of the tyrosine pathway to the catabolism of phenylalanine in Brevibacterium linens 47

Lee, C

doi:10.1016/0378-1097(86)90193-x

Cited by 4 publications

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“…This suggests that the pathway originally annotated as the phh pathway may not be the only pathway involved in the initial catabolism of this aromatic amino acid in this strain. It should also be mentioned that for some Gram-positive and Gram-negative bacteria the production of phenylpyruvate during degradation of phenylalanine has been reported (Lee and Desmazeaud, 1986;Spaepen et al, 2007). This alternative pathway may involve the transamination of the amino group of phenylalanine into a 2-keto acid leading to the production of phenylpyruvate and the corresponding amino acid (i.e.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of the PhhR regulon in Pseudomonas putida

Herrera

Duque

Rodríguez‐Herva³

et al. 2010

Environmental Microbiology

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SummaryPseudomonas putida is a soil microorganism that utilizes aromatic amino acids present in root exudates as a nitrogen source. We have previously shown that the PhhR transcriptional regulator induces phhAB genes encoding a phenylalanine hydroxylase. In this study we show, using microarray assays and promoter fusions, that PhhR is a global regulator responsible for the activation of genes essential for phenylalanine degradation, phenylalanine homeostasis and other genes of unknown function. Recently, it has been shown that phenylalanine catabolism occurs through more than one pathway. One of these possible pathways involves the metabolism of phenylalanine via tyrosine, p-hydroxyphenylpyruvate, and homogentisate. We identified two genes within this pathway that encode an acyl-CoA transferase involved in the metabolism of acetoacetate. All genes in this pathway were induced in response to phenylalanine in a PhhR-proficient background. The second potential degradative pathway involves the degradation of phenylalanine to produce phenylpyruvate, which seems to be degraded via phenylacetyl-CoA. A number of mutants in the paa genes encoding phenylacetyl-CoA degradation enzymes fail to grow on phenylpyruvate or phenylacetate, further supporting the existence of this second pathway. We found that the PhhR regulon also includes genes involved in the biosynthesis of aromatic amino acids that are repressed in the presence of phenylalanine, suggesting the possibility of feedback at the transcriptional level. In addition, we found that PhhR modulates the level of expression of the broad-substrate-specificity MexEF/OprN efflux pump. Expression from this pump is under the control of mexT gene product because phenylalanine-dependent transcription from the mexE promoter does not occur in a mexT mutant background. These results place PhhR as an important regulator in the control of bacterial responses to aromatic amino acids.

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Section: Introductionmentioning

confidence: 99%

Identification and characterization of the PhhR regulon in Pseudomonas putida

Herrera

Duque

Rodríguez‐Herva³

et al. 2010

Environmental Microbiology

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“…1975), Mycobacterium rhodochrous (Sparnins and Chapman 1976), Flavobacterium sp. (Lee and Desmazeud 1986; van den Tweel et al. 1988), Xanthobacter sp .…”

Section: Introductionmentioning

confidence: 99%

Tyrosol degradation via the homogentisic acid pathway in a newly isolatedHalomonasstrain from olive processing effluents

Liebgott

Labat

Amouric

et al. 2008

Journal of Applied Microbiology

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Aims: To isolate a new Halomonas sp. strain capable of degrading tyrosol, a toxic compound present in olive mill wastewater, through the homogentisic acid (HGA) pathway. Methods and Results: A moderately halophilic Gram‐negative bacterium belonging to the Halomonas genus and designated strain TYRC17 was isolated from olive processing effluents. This strain was able to completely degrade tyrosol (2‐(p‐hydroxyphenyl)‐ethanol), a toxic compound found in such effluent. Tyrosol degradation begins by an oxidation to 4‐hydroxyphenylacetic acid (HPA), which is then converted into HGA by an HPA 1‐monooxygenase, while closest Halomonas species degrade tyrosol through 3,4‐dihydroxyphenylacetic acid (DHPA). In the presence of transition metals, HGA underwent a pH‐dependent abiotic conversion into benzoquinone acetic acid, then into 2,5‐dihydroxybenzaldehyde (gentisaldehyde) and pyomelanin, by oxidative decarboxylation and polymerization, respectively. Conclusions: Tyrosol degradation via HGA by the new Halomonas sp. strain TYRC17 was complete in the absence of trace elements. In their presence, HGA was abiotically converted into gentisaldehyde and pyomelanin. Significance and Impact of the Study: This is the first report on tyrosol degradation via the HGA pathway under hypersaline conditions and on the oxidative decarboxylation of HGA into gentisaldehyde. It underlines the importance of the Halomonas genus in the bioremediation of toxic‐contaminated sites.

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“…These three strains can also produce benzaldehyde from tryptophan catabolism [12]. Tyrosine is degraded by Brevibacterium linens 47 by phenylalanine pathway [21] (Figure 4).…”

Section: Generation Of Aromas and Flavoursmentioning

confidence: 99%

Natural Flavours Obtained by Microbiological Pathway

Petrovici¹,

Ciolacu²

2018

Generation of Aromas and Flavours

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In the last years, the demands for natural flavours have dramatically increased. To fulfil the consumer requests, researchers are looking for new and alternative methods to obtain qualitative aroma compounds by utilising microbiological pathways. Some microorganisms like lactic acid bacteria or yeasts are capable of synthesising specific flavours corresponding to diacetyl and acetaldehyde as secondary metabolites. By supplying the culture media with flavour precursors and optimising the primary culture media, high amount of specific flavours could be obtained. Also, the biosynthesis of each specific flavour is influenced by the type of amino acids and sugars involved in the bioprocess. Thus, by changing the ratio of amino acids and sugars in the culture media, different amounts of flavour can be obtained. In this context, monitoring the compositions of the culture media and fermentation conditions is crucial in obtaining high amounts of a qualitative-specific aroma.

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Evaluation of the contribution of the tyrosine pathway to the catabolism of phenylalanine in Brevibacterium linens 47

Cited by 4 publications

References 0 publications

Identification and characterization of the PhhR regulon in Pseudomonas putida

Identification and characterization of the PhhR regulon in Pseudomonas putida

Tyrosol degradation via the homogentisic acid pathway in a newly isolatedHalomonasstrain from olive processing effluents

Natural Flavours Obtained by Microbiological Pathway

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