Isolation and characterisation of an enterocin P-producing Enterococcus lactis strain from a fresh shrimp (Penaeus vannamei).

Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity. 16S rRNA, rpoA and pheS gene sequencing, as well as the 16S-23S rRNA intergenic spacer analyses, were combined to identify strain Q1 as a strain of Enterococcus lactis. The bacteriocin produced by E. lactis Q1 is thermostable, active in the pH range from 4.0 to 9.0 and has a bactericidal mode of action. The enterocin P structural gene was detected by specific PCR in strain E. lactis Q1, which is in good agreement with SDS-PAGE data of the purified bacteriocin. A lack of significant antibiotic resistance genes and virulence determinants was confirmed by specific PCRs. This work provides the first description of an enterocin P producer E. lactis strain isolated from a fresh shrimp. Based on its safety properties (absence of haemolytic activity, virulence factors and antibiotic resistance genes), this strain has the potential to be used as a natural additive or adjunct protective culture in food biopreservation and/or probiotic culture.

[Vitamins A, E and leptin in obese and non-insulin-dependent diabetes]. / Statut en vitamines a, e et léptinémie chez un groupe d'obèses diabétiques non insulino-dépendant.

BACKGROUND: At the obese ones, there is an imbalance between the free defenses antioxydants and radicals from where the installation of an oxydative stress, responsible for the development of non-insulin-dependent diabetes. AIM: Our objectives was to evaluate the levels of vitamins A, E and of leptin, to search the link witch could exist between vitamins and leptin. METHODOLOGY: We proportioned the rates in vitamins A, E and in leptine at 30 obese subjects diabetic of type 2 including 12 men and 18 women of average age (50.93 +/- 6.13) years not carrying pathologies other than the diabetes and obesity compared to 30 witnesses who theirs are paired according to the age and the sex.. RESULTS: Our results chows that levels of antioxidants did not differ between the two groups but we find a non significant decrease in vitamin E/(TC +TG) ratio (1.86 +/- 0.38 vs. 2.11 +/- 0.74 ; p = 0.08) and significant increase of vitamin A level in women obese with non-insulin-diabetes mellitus compared with control group of women (0.69 +/- 0.16 vs. 0.55 +/- 0.15 ; p = 0.01). Moreover a negative and significative correlation between vitamin E and leptin (r = 0.452 ; p = 0.01), and a negative and no significative correlation between vitamin A and leptin (2 = - 0.221; p > 0.05) were observed. CONCLUSION: The rate of vitamin A, is different for each sex with share. The vitamin E could have a negative control on the secretion of the leptin.