Due to the increasing interest for healthy foods, the feasibility of using fresh-cut fruits to vehicle probiotic microorganisms is arising scientific interest. With this aim, the survival of probiotic lactic acid bacteria, belonging to Lactobacillus plantarum and Lactobacillus fermentum species, was monitored on artificially inoculated pineapple pieces throughout storage. The main nutritional, physicochemical, and sensorial parameters of minimally processed pineapples were monitored. Finally, probiotic Lactobacillus were further investigated for their antagonistic effect against Listeria monocytogenes and Escherichia coli O157:H7 on pineapple plugs. Our results show that at eight days of storage, the concentration of L. plantarum and L. fermentum on pineapples pieces ranged between 7.3 and 6.3 log cfu g−1, respectively, without affecting the final quality of the fresh-cut pineapple. The antagonistic assays indicated that L. plantarum was able to inhibit the growth of both pathogens, while L. fermentum was effective only against L. monocytogenes. This study suggests that both L. plantarum and L. fermentum could be successfully applied during processing of fresh-cut pineapples, contributing at the same time to inducing a protective effect against relevant foodborne pathogens.

G . S P A N O , V . C A P O Z Z I , A . V E R N I L E A N D S . M A S S A . 2004.Aim: Understanding the molecular response to stress tolerance of wine Lactobacillus plantarum. Methods and Results: Two genes codifying for heat shock proteins were cloned from wine L. plantarum. The coding regions of the two heat shock genes are 420 and 444 nucleotides long, and started with an ATG codon suggesting that they were translated. The protein sequences deduced from the isolated genes have a molecular mass of 18AE483 and 19AE282 kDa, respectively, and were therefore named hsp18AE5 and hsp19AE3. The expression of small heat shock genes was analysed by RT-PCR analysis. Moreover, the 5¢ and 3¢ noncoding regions were cloned and sequenced. Conclusions: The expression of the heat shock genes was strongly induced by heat, cold and ethanol stress. Analysis of the 5¢ and 3¢ flanking regions of hsp18AE5 and hsp19AE3 genes, revealed the presence of an inverted repeat sequence (TTAGCACTC-N 9 -GAGTGCTAA) homologue to the CIRCE elements found to the upstream regulatory region of heat shock operons, and an inverted sequence that could form a stem and loop structure that it is likely to function as a transcriptional terminator. Based on their structures, the genes were classified as belonging to Class I of heat shock genes according to the B. subtilis nomenclature of heat response genes. Significance and Impact of the Study: Small heat shock genes isolated from wine L. plantarum might have a role in preventing damage by cold stress.

We have investigated the prevalence of spoilage lactic acid bacteria (LAB) in table wines produced in the Apulia region. The occurrence of LAB was evaluated in wines produced with low sulphur dioxide doses and not supplemented with selected malolactic starters such as Oenococcus oeni. About 150 strains were isolated from wine must and a molecular characterization was performed using PCR-based techniques. Most of the strains analysed belonged to Lactobacillus plantarum species. However, some of the strains were identified as Pediococcus damnosus and Leuconostoc sp. The amplified fragments of Pediococcus damnosus were cloned and sequenced. The coding sequence was highly homologous to that of the ropy plasmid confirming that the isolated strain was a ropy(+) Pediococcus damnosus. In all the samples analysed, the final must pH value reached was relatively high (from 3.78 to 3.90). The high pH values had probably negatively influenced (counteracted) the activity of sulphur dioxide added, allowing proliferation of spoilage wine microorganisms.

-A total of 468 lactic acid bacteria (LAB) isolates from the interior of six traditional Pecorino Siciliano cheeses during ripening (1, 30 and 90 days) were characterized genotypically in order to assess the biodiversity within this wild microbial population. Two DNA-based technique, PCR and PFGE were used for genetic typing of isolates. Of the 468 isolates, species-specific PCR analysis showed that 79, 58, 2, 9 and 4 isolates reacted with primers for Lactobacillus paracasei, Lb. plantarum, Lb. pentosus, Lb. rhamnosus and Lb. curvatus, respectively and no isolates reacted with the Lb. casei primers. Genus-specific PCR analysis showed that 59 isolates reacted positively with the lactococcal primers, 221 with the enterococcal primers and 34 with the Leuconostoc primers, 1 with the pediococcal primers and 4 with the streptococcal primers. Enterococci were characterized at species level and twelve of the 221 enterococci isolates showed positive reaction with the E. faecalis species-specific primers, and the remainder 209 isolates positively with the E. faecium species-specific primers. PFGE analysis allowed to identify different strains of the same species of Lb. plantarum and Lb. paracasei. The strains which reacted positively with Lb. curvatus, Lb. pentosus or Lb. rhamnosus primers gave a unique PFGE pattern. PFGE indicated 52 different band patterns for enterococci, 9 for lactococci, 5 for leuconostocs and 1 for streptococci and pediococci. The results suggest that wild bacterial populations should be preserved in order to protect the traditional raw milk cheeses, and to select new specific strains for the dairy industry.

Abtract Aims:  Monitoring the occurrence of the human pathogen Vibrio vulnificus in a mussel farm located in the lagoon of Varano (Italy). Methods and Results:  A total of 72 samples of mussel, water and sediment, collected from two locations of Varano lagoon in the Gargano peninsula, during a 7‐ month survey, were analysed. Isolation and PCR characterization of six V. vulnificus environmental genotype strains revealed that this pathogen was isolated when with T was above 22°C and salinity ranged between 22·7 and 26·4‰. No significant correlation of the occurrence of V. vulnificus with water pH or salinity was observed. Moreover, 8% of mussel samples were found to be contaminated by V. vulnificus. All of that positive mussel samples originated from the same sampling station. Conclusion:  It is suggested that warmer season are risky to eat raw or undercooked bivalve molluscs in the local area. Significance and Impact of the Study:  To increase knowledge about environmental conditions that may affect the occurrence of waterborne pathogen Vibrio vulnificus in seafood.