M.C. Manca de Nadra

Biogenic amine production by Lactobacillus

M.E. ARENA AND M.C. MANCA DE NADRA. 2001.

Arginine, citrulline and ornithine metabolism by lactic acid bacteria from wine.

The catabolism of arginine, an amino acid found in grape juice and wine, citrulline and ornithine was investigated in four lactic acid bacteria. Only Lactobacillus hilgardii X1B catabolized arginine and excreted citrulline into the medium. The recovery of arginine as ornithine was lower than the expected theoretical value. The arginase-urease pathway was not detected indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway. Oenococcus oeni m, a strain not able to utilize arginine, degraded citrulline that was completely recovered as ornithine, ammonia and CO2. Lactobacillus hilgardii X1B catabolized citrulline but it was only 44% recovered as ornithine. The citrulline utilization by Oenococcus oeni m may be important for two reasons: it can gain extra energy for growth from citrulline metabolism, and the amino-acid diminution could avoid the possibility of ethyl carbamate formation from the citrulline naturally present in wine.

Pediocin N5p from Pediococcus pentosaceus: adsorption on bacterial strains

Abstract Pediocin N5p is a bacteriocin produced by Pediococcus pentosaceus isolated from wine. It is adsorbed on both sensitive and resistant Gram-positive and Gram-negative bacteria in non specific (non lethal) sites and higher values, up to 30% are observed in sensitive strains suggesting the presence of particular (lethal) receptors. Cell death without lysis is produced by the action of pediocin on sensitive strains. The cations Mg 2 + and Mn 2 + increase the pediocin binding by 80 and 100%, respectively. Treatment of sensitive cells with proteolytic enzymes and 1% SDS increases the subsequent binding of bacteriocin by 100 and 25%, respectively. As a lipid moiety of pediocin N5p is critical to its activity, probably a hydrophobic interaction with the peptidic receptor, stabilized by Mn 2 + or Mg 2 + might be established. Pediocin N5p adsorption is not affected by ethanol and SO 2 , two factors involved in vinification.

Factors affecting the production of putrescine from agmatine by Lactobacillus hilgardii X1B isolated from wine

Aims:  To elucidate and characterize the metabolic putrescine synthesis pathway from agmatine by Lactobacillus hilgardii X1B.

Arginine dihydrolase pathway in Lactobacillus plantarum from orange.

Lactobacillus plantarum N8 and N4 strains isolated from orange degraded L-arginine to citrulline, ornithine and ammonia. Citrulline and ornithine were consumed. Lactobacillus plantarum N4 utilized arginine and ornithine to a higher extent than Lactobacillus plantarum N8. Urea was not detected during arginine degradation, indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway. Citrulline increased the growth of the two strains, arginine only increased the growth of Lactobacillus plantarum N4. Ornithine did not modify the growth of the strains studied. With different behavior, Lactobacillus plantarum N8 and N4 strains were able to derive energy and ammonia from arginine or citrulline catabolism. This is interesting for microorganisms developing in a stressful environment.

Comparative survey of putrescine production from agmatine deamination in different bacteria.

This article aims to study putrescine production in Lactobacillus hilgardii strain X(1)B, an agmatine degrader isolated from wine, and to compare it with three other different species, previously reported as putrescine producers from agmatine: Pseudomonas aeruginosa PAO1, Enterococcus faecalis ATCC11700 and Bacillus cereus CECT 148(T). The effect of different biogenic amines, organic acids, cofactors, amino acids and sugars on putrescine production was evaluated. In some cases, a similar effect was found in all the strains studied but the magnitude differed. Arginine, glucose and fructose showed an inhibitory effect, whereas the presence of agmatine induced the production of putrescine in all microorganisms. In other cases, the effect differed between P. aeruginosa PAO1 and the other microorganisms. Histamine and tyramine poorly influenced the utilization of agmatine, although a small increase in putrescine production was observed in P. aeruginosa PAO1. Succinate, spermidine and spermine also led to an increase in putrescine production in P. aeruginosa PAO1, whereas the succinate had no effect in the other microorganisms. Spermine and spermidine always produced a diminution in agmatine deamination. In this work, we have also demonstrated that pyridoxal 5-phosphate, Mg(2+) and Mn(2+) had no effect on putrescine production from agmatine. Results presented in this paper indicate differences in regulation mechanisms of agmatine deiminase pathway among P. aeruginosa PAO1 and L. hilgardii X(1)B, E. faecalis ATCC11700 and B. cereus CECT 148(T). These results are significant from two points of view, first food quality, and second the toxicological and microbiological aspects. It should be taken into account that putrescine, whose origin is still controversial, is quantitatively the main biogenic amine found in food.

Effect of l‐malic and citric acids metabolism on the essential amino acid requirements for Oenococcus oeni growth

Aims: The purpose of this work was to study the effect of l‐malic and/or citric acids on Oenococcus oeni m growth in deficient nutritional conditions, and their roles as possible biosynthetic precursors of the essential amino acids. 
Methods and Results: Bacterial cultures were performed in synthetic media. Bacterial growth rate was reduced or annulled when one amino acid was omitted from basal medium, especially for members of aspartate family, except lysine. The organic acids increased or restored the growth rates to the respective reference values. In each medium deficient in one essential amino acid, the l‐malic acid utilization was accompanied by an increase of l‐lactic acid concentration and accounted for approximately 100%l‐malic acid consumed. d‐Lactic acid formation from glucose decreased in the medium without cysteine. Except for tyrosine, the recovery of glucose–citrate as d‐lactic acid was lower than in the complete medium when asparagine, isoleucine or cysteine were excluded. The ethanol and acetate production was not modified. 
Conclusions:l‐Malic and citric acids favoured Oenococcus oeni m growth in nutritional stress conditions. Specifically citric acid was involved in the biosynthesis of the aspartate‐derived essential amino acids and glucose in the cysteine biosynthesis. 
Significance and Impact of the Study: Such beneficial effect of l‐malic and citric acids on amino acids requirements of Oenococcus oeni m have great significance considering the low amino acids concentration in wine.

Exoprotease activity of Leuconostoc oenos in stress conditions

Exoprotease activity during 48 h of total energy and nutrient starvation was examined in Leuconostoc oenos X2L isolated from wine. Starved cells after 2 h of incubation at 30 °C in citrate buffer, 0.05 mmol 1−1 pH 5, showed greater extracellular proteolytic activity than at the onset of starvation. In the presence of 60 mg l−1 SO2 and 8% or 12% ethanol, the proteolytic activity was higher ; 10 mmol l−1 Ca2+ and Mg2+ produced an increase in protease activity during starvation. Glucose and 2‐deoxyglucose (2‐DOG) were found to repress synthesis by 80% and 100%, respectively. Cyclic adenosine 3′‐5′‐phosphate increased the exoprotease activity and reverted the repression by glucose and 2‐DOG. De novo synthesis of proteins was required for the exoprotease activity by cells submitted to stress conditions. The absence of protease activity in the supernatant fluids from chloramphenicol‐treated cells indicated that the activity is a result of deliberate release and not of passive cell lysis.

Flocculation and cell surface characterization of Kloeckera apiculata from wine

Aims: To characterize and analyze the flocculation phenomenon of Kloeckera apiculata mc1 from Agentinian wine to understand the cell–cell interaction pattern.

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

Aims:  To investigate amino acid and dipeptide utilization by Lactobacillus plantarum N4 isolated from orange peel, in a nutritionally depleted medium based on MRS (Mann, Rogosa, Sharpe).