The role of two families of bacterial enzymes in putrescine synthesis from agmatine via agmatine deiminase

Putrescine, one of the main biogenic amines associated to microbial food spoilage, can be formed by bacteriafrom arginine via ornithine decarboxylase (ODC), or from agmatine via agmatine deiminase (AgDI). This study aims to correlate putrescine production from agmatine to the pathway involving N-carbamoylputrescine formation via AdDI (the aguAproduct) and N-carbamoylputrescine amidohydrolase (the aguB product), or putrescine carbamoyltransferase (the ptcA product) in bacteria. PCR methods were developed to detect the two genes involved in putrescine production from agmatine.Putrescine production from agmatine could be linked to the  aguA and  ptcA genes in  Lactobacillus hilgardii X1B,Enterococcus faecalis ATCC 11700, and Bacillus cereus ATCC 14579. By contrast Lactobacillus sakei 23K was unable toproduce putrescine, and although a fragment of DNA corresponding to the gene aguA was amplified, no amplification wasobserved for the ptcA gene. Pseudomonasaeruginosa PAO1 produces putrescine and is reported to harbour aguA and aguBgenes, responsible for agmatine deiminase and N-carbamoylputrescine amidohydrolase activities. The enzyme from P. aeruginosa PAO1 that converts N-carbamoylputrescine to putrescine (the aguB product) is different from other microorganismsstudied (the ptcA product). Therefore, the aguB gene from P. aeruginosa PAO1 could not be amplified with ptcA specificprimers. The aguB and ptcA genes have frequently been erroneously annotated in the past, as in fact these two enzymes areneither homologous nor analogous. Furthermore, the aguA, aguB and ptcA sequences available from GenBank were subjected to phylogenetic analysis, revealing that gram-positive bacteria harboured ptcA, whereas gram-negative bacteria harbouraguB. This paper also discusses the role of the agmatine deiminase system (AgDS) in acid stress resistance.&nbsp

Maria C. Manca de Nadra, Mario E. Arena and Fabiana M. Saguir

It is well known that lactic acid bacteria need multiple nutritional requirements for growth. They require numerous amino acids and other growth factors to develop in synthetic media. In this review the amino acid requirements, the effect of L-malic acid and citric acids metabolism on these requirements and the catabolism of amino acids by lactic acid bacteria from wine are discussed, with emphasis on arginine and its amino acid derivates: citrulline and ornithinFil: manca de Nadra, Maria C.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Saguir de Zucal, Fabiana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaFil: Arena, Mario Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin

Utilization of amino acids and dipeptides by Lactobacillus plantarum from orange in nutritionally stressed conditions

To investigate amino acid and dipeptide utilization by Lactobacillus plantarum N4 isolated from orange peel, in a nutritionally depleted medium basedon MRS (Mann, Rogosa, Sharpe).Methods and Results: In MRS with 0 Æ1 g l)1 of meat extract and without peptone and yeast extract, growth increased when essential and stimulatory amino acids and nonessential amino acid were added to the medium. Replacement of the essential amino acid, leucine, and the nonessential amino acid, glycine, byleucyl-leucine (Leu-Leu) and ⁄or glycyl-glycine (Gly-Gly) significantly enhancedgrowth. Essential amino acids were mainly consumed and the dipeptides were almost completely used at the end of growth. Leucine and glycine accumulatedinternally from the peptides were higher than from the free amino acids.Glucose utilization increased in the media containing dipeptides comparedwith the medium containing free amino acids.Conclusions: In a N-depleted medium, Leu-Leu and ⁄or Gly-Gly were more effective than the respective amino acids in supporting growth of the microorganism. The more efficient internal accumulation of glycine and especially leucine from dipeptides confirmed the ability of the strain to assimilate mainly complex nitrogen molecules rather than simple ones.Significance and Impact of the Study: The ability of Lact. plantarum N4 to efficiently use dipeptides could contribute to spoilage development in the natural medium of the organism, orange juiceFil: Saguir de Zucal, Fabiana Maria. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Loto Campos, Iris Eleonora. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; ArgentinaFil: Manca de Nadra, M. C.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

Identification of dominant lactic acid bacteria isolated from grape juices: Assessment of its biochemical activities relevant to flavor development in wine

We investigated the dominant lactic acid bacteria (LAB) from grape juice and commencement of malolactic fermentation (MLF) samples of a cellar located in Argentina and assessment of its β-glucosidase activity and butter aroma compounds production. LAB number found in grape juice (approximately log10 3.3) was lower than that obtained in the MLF samples. Oenococcus oeni was predominant, accounting for 68% of the 81 LAB isolated. Majority of whole cells derived from O. oeni cultures at the end of the exponential growth showed detectable β-glucosidase activity. Contrarily, the highest proportion of them did not produce diacetyl, acetoin, and 2,3-butylene glycol. A direct relation between both properties among the O. oeni strains could not be established. In the selected MS25 strain, l-malic acid was compatible with good enzyme activity and was partially able to annul the negative influence of the low pH (3.8). In different conditions, the aroma compounds were lower than 4 mg/ml, especially at pH 3.8 and in presence of l-malic acid (2.5 g/l). This strain could have adequate characteristics for potential use in winemaking. Finally, the assessment of both biochemical properties in O. oeni should be considered as a quality criterion for selecting starter cultures for the improvement of the wines aroma.Fil: Saguir de Zucal, Fabiana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Loto Campos, Iris Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Maturano, Ramona del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Manca de Nadra, María C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin

Characterization and amino acid metabolism performances of indigenous Oenococcus oeni isolated from Chinese wines

Oenococcus oeni is a multiple physical stress-tolerant lactic acid bacterium that plays an important role in wine making. It is often added as a starter culture to carry out malolactic fermentation (MLF). In this study, a total of 22 out of 127 lactic acid bacteria, isolated from Chinese wines undergoing MLF, were identified as O. oeni by species-specific PCR and 16S rRNA sequencing. Single-enzyme amplified fragment length polymorphism (SE-AFLP) analysis showed that all strains could be typed under these conditions, and three main groups were determined by cluster analysis, which showed intraspecific homology higher than 69� %. Eight strains, representative of SE-AFLP clusters, were tested for malolactic activity. Significant differences were observed among strains with regard to the amount of malic acid consumed. Seventeen amino acids in different wines that were inoculated by 4 O. oeni strains, respectively, were analyzed before and after MLF. The results indicated that the amino acid metabolism of the 4 strains was significantly different between each strain.Gang Jin, Hua Wang, Chunhui Zhang, Cuixia Li, Liye Du, Paul R. Grbin and Hua L

Genotypic and phenotypic diversity of Pediococcus pentosaceus strains isolated from food matrices and characterisation of the penocin operon

Lactic acid bacteria (LAB) are widely used in the food industry. Pediococcus spp. belong to the LAB group and include several species that are essential for the quality of fermented food. Pediococcus pentosaceus is the species that is most frequently isolated from fermented food and beverages but its uncontrolled growth during food fermentation processes can contribute to undesired flavours. Hence, the characterisation of these bacteria at the strain level is of great importance for the quality of fermented products. Despite their importance, misidentification at the species level is common for members of the genus Pediococcus. To clarify the taxonomic relationships among strains, a multilocus sequencing approach was developed for the characterisation of a collection of 29 field strains, 1 type strain and 1 reference strain of P. pentosaceus isolated from food. These strains were also tested for several phenotypic properties of technological interest and for the production of bacteriocins. The chromosomal operon involved in the synthesis of the bacteriocin penocin was also investigated. The present study enabled a good genomic characterisation, identifying 17 sequence types, with an overview of phenotypic characteristics related to different technological abilities, and also provides a thorough characterisation of the operon involved in penocin production