Putative Pseudomonas spp. (102 isolates) from different foods were first characterised by API 20NE and then tested for some enzymatic activities (lipase and lecithinase production, starch hydrolysis and proteolytic activity). However subsequent molecular tests did not always confirm the results obtained, thus highlighting the limits of API 20NE. Instead RFLP ITS1 and the sequencing of 16S rRNA gene grouped the isolates into 6 clusters: Pseudomonas fluorescens (cluster I), Pseudomonas fragi (cluster II and V) Pseudomonas migulae (cluster III), Pseudomonas aeruginosa (cluster IV) and Pseudomonas chicorii (cluster VI). The pectinolytic activity was typical of species isolated from vegetable products, especially Pseudomonas fluorescens. Instead Pseudomonas fragi, predominantly isolated from meat was characterised by proteolytic and lipolytic activities.

The paper provides a simple protocol that uses the polymerase chain reaction to amplify a specific portion of the 16S gene, allowing the recognition of Pseudomonas fluorescens from other group I Pseudomonas. The amplified DNA patterns of 16S rRNA and ITS1, from the restriction fragment length polymorphisms VspI, HaeIII and TaqI digestion, produced band patterns that distinguished the biotypes of Ps. fluorescens. In addition to distinguishing the biotypes C and 3 we used a phenotypical method for levan production.

Heterofermentative lactic acid bacteria belonging to the genus Carnobacterium are currently divided into seven different species, C. piscicola, C. mobile, C. gallinarum, C. inhibens, C. divergens, C. funditum, and C. alterfunditum. 16S rDNA-targeted PCR assay was carried out for the identification of the genus Carnobacterium. In addition, type strains of all Carnobacterium species were analyzed by 16S-23S rDNA intergenic spacer analysis in comparison with type strains of phylogenetically related lactic acid bacteria. These methods enabled the identification and the discrimination among Carnobacterium species and the other phylogenetically related lactic acid bacteria. Likewise, analogous results were obtained by restriction analysis of amplified 16S rDNA performed with HaeIII and HinfI as restriction enzymes.

Reclassification of Lactobacillus maltaromicus (Miller et al. 1974 , 1984;Shaw & Harding, 1985). Collins et al. (1991) inferred the phylogenetic relationships among Lactobacillus species, Carnobacterium species and related lactic acid bacteria on the basis of 16S rDNA sequence data. In that study, Collins and colleagues suggested the revision of the taxonomic position of Lactobacillus maltaromicus due to the high 16S rDNA sequence similarity (100 % sequence similarity for a comparison based on 1340 nt of 16S rDNA sequence) detected between this species and C. piscicola, formerly Lactobacillus piscicola (Hiu et al., 1984). L. maltaromicus was first described by Miller et al. (1974) as a new lactic acid bacteria isolated from milk and producing a malty-like flavour and aroma.In this study, a phenotypic and genotypic comparison among L. maltaromicus strains DSM 20342 T and DSM 20344 (Miller et al., 1974) and C. piscicola strains DSM 20730 T and DSM 20722 was carried out with the aim of clarifying the taxonomic position of these two species. Specifically, the aforementioned Lactobacillus and Carnobacterium species were compared by evaluating their carbohydrate fermentation patterns, by determining whether meso-diaminopimelic acid was present in their cellwall composition, and by determining the nature of the enantiomeric form of the lactic acid produced by their metabolism. Moreover, all the strains were characterized genetically by restriction analysis of their amplified 16S rDNA, by amplification of the internal transcribed spacers between their 16S and 23S rDNA and by evaluation of their DNA-DNA relatedness.

A number of strains of Lactobacillus spp. from foods were screened for their ability to convert meso-2,3-butanediol into 2-butanol. Only three strains of L. brevis transformed the meso-diol into the secondary alcohol. These strains as well as the others unable to metabolize meso-2,3-butanediol exhibited the capacity to hydrogenate 2-butanone to 2-butanol. In both types of lactobacilli, an inverse relationship was observed between the diol or ketone concentration and the abundance of the R form of 2-butanol. This fact has been interpreted in terms of a co-occurrence of two dehydrogenases, both acting on the ketone with different kinetic parameters and opposite enantioselectivities. These results represent a further support to the assumption that 2-butanol present in distillates originates from the enzymatic activity of lactobacilli growing on mashes and give the most likely explanation of the enantiomeric excess of (R)-2-butanol generally found in distillates. Keywords: 2-Butanol; meso-2,3-butanediol; lactobacilli; diacetyl; acetoin; dehydrogenases