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Papers by Francesco Villani
Meat Science, 2004
A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fer... more A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fermented sausages after enrichment in MRS broth at pH 2.5 followed by bile salt stressing (1% bile salts w/v). One hundred and fifty acid- and bile-resistant strains were selected, avoiding preliminary and time-consuming isolation steps. Strains were further characterized for survival at pH 2.5 for 3 h in phosphate-buffered saline and for growth in the presence of 0.3% bile salts with and without pre-exposure at low pH. Twenty-eight strains showed a survival >80% at pH 2.5 for 3 h; moreover, most of the strains were able to grow in the presence of 0.3% bile salts. Low pH and bile resistance was shown to be dependent on both the species, identified by phenotypic and molecular methods, and the strain tested. This is the first report on the direct selection of potentially probiotic lactobacilli from dry fermented sausages. Technologically interesting strains may be used in the future as probiotic starter cultures for novel fermented sausage manufacture.
Journal of Applied Microbiology, 2004
Journal of Applied Microbiology, 1997
International Journal of Food Microbiology, 1995
Streptococcus thermophilus 347 isolated from yogurt produces a bacteriocin referred as thermophil... more Streptococcus thermophilus 347 isolated from yogurt produces a bacteriocin referred as thermophilin 347. The bacteriocin was evidenced in the neutralized, filtered and catalase treated culture supernatant fluid of the producer strain. After partial purification, thermophilin 347 exhibited a bactericidal effect against Listeria monocytogenes and several closely related lactic acid bacteria. The activity of thermophilin 347 was lost after protease treatment but was maintained after heating at 100 degrees C for 1 h; after autoclaving at 121 degrees C for 15 min the activity was reduced by 50%. SDS-PAGE of partially purified thermophilin 347 was used to detect bacteriocin activity corresponding to an apparent molecular mass between 2.5 and 6.2 KDa.
International Journal of Food Microbiology, 2001
In this work we studied using different molecular methods the population dynamics of nisin-produc... more In this work we studied using different molecular methods the population dynamics of nisin-producing organisms and the persistence of such organisms within a complex ecosystem, 'Fior di latte' cheese, a traditional high-moisture pasta filata cheese. Using the primers targeting the eubacterial 16S-23S rRNA spacer region, together with those amplifying the nisA or nisZ gene, we were able to provide a rapid species identification of the isolates. Inhibitors of Lactococcus lactis subsp. lactis DSM 20481T used as indicator occurred during the whole process of cheese manufacture as a significant part of lactic microflora; however, only 12 among 109 isolates of bacteriocin producers were nisin producers. Amplification of the nisA or nisZ gene, using DNA extracted directly from dairy samples as templates, showed that the nisin structural gene was detected during cheese-making from milk samples up to the end of curd ripening but not in the final cheese. In order to monitor nisin-producing strains during cheese manufacturing, the 12 Lactococcus lactis nis+ strains were analysed by low frequency restriction fragment and PFGE. Nine isolates among the 12 nisin-producers exhibited an unique and distinct DNA banding pattern and are considered to be genetically diverse. The other three isolates from curd after ripening showed the same restriction pattern and could be the same strain. In fact, it was also isolated 2 months after the first analysis of cheese-making of 'Fior di latte'.
Journal of Applied Microbiology, 2004
Applied and Environmental Microbiology, 2000
Meat Science, 2004
The aims of this study were to characterize the population of Micrococcaceae in different types o... more The aims of this study were to characterize the population of Micrococcaceae in different types of fermented sausages of Southern Italy and to determine the technological properties of Staphylococcus strains in order to evaluate the suitability of selected strains as starter cultures in the processing of dry fermented pork sausages. Ninety-six strains were studied to evaluate nitrate reductase, proteolytic, lipolytic and antioxidant activities as well as growth ability at different temperatures, pH's and NaCl concentrations. All the strains were classified as Staphylococcus except for one isolate assigned to Kocuria spp. The species most often isolated were S. saprophyticus, S. xylosus and S. equorum, although they were not equally distributed within the different sausages. Other species isolated were, in descending order of abundance, S. succinus, S. warneri, S. lentus, S. vitulus, S. pasteuri, S. epidermidis, and S. haemolyticus. In general, the S. xylosus strains exhibited the best technological properties that would make them eligible as good starter cultures for fermented meat products. However, strains belonging to other species also showed good technological properties. Finally, all strains grew at 10, 15 and 20 °C, in the presence of 10% and 15% of NaCl and at pH 5.0 and 5.5. The results showed that it is possible to formulate a broad variety of staphylococcal starter cultures, adaptable to different technological conditions and sausage manufacture practices.
Applied and Environmental Microbiology, 2006
Applied and Environmental Microbiology, 2001
Journal of Applied Microbiology, 2004
Journal of Applied Microbiology, 1993
F. VILLANI, G. SALZANO, E. SORRENTINO, O. PEPE, P. MARINO AND S. COPPOLA. 1993. Enterococcus faec... more F. VILLANI, G. SALZANO, E. SORRENTINO, O. PEPE, P. MARINO AND S. COPPOLA. 1993. Enterococcus faecalis 226, isolated from natural whey cultures utilized as starters in the manufacture of mozzarella cheese from water-buffalo milk, produces a bacteriocin designated enterocin 226NWC. The bacteriocin was isolated from culture supernatant fluids of the producer strain and was active against strains of the same species and Listeria monocytogenes, but not against useful lactic acid bacteria. Enterocin 226NWC is a protein with an apparent molecular weight of about 5800; it is relatively heat-stable and has a bactericidal mode of action. Listeria monocytogenes, growing in the presence of the enterocin 226NWC producer strain in broth and in reconstituted skim milk, was inhibited.
Systematic and Applied Microbiology, 2003
Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (PCR-D... more Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (PCR-DGGE) and 16S-23S rDNA intergenic spacer region polymorphism (ISR-PCR) analyses were tested as tool for differentiation of staphylococcal strains commonly isolated from fermented sausages. Variable V3 regions of 25 staphylococcal reference strains and 96 wild strains of species belonging to the genera Staphylococcus, Micrococcus and Kocuria were analyzed. PCR-DGGE profiles obtained were species-specific for S. sciuri, S. haemolyticus, S. hominis, S. auricularis, S. condimenti, S. kloosi, S. vitulus, S. succinus, S. pasteuri, S. capitis and S. (Macrococcus) caseolyticus. Moreover, 7 groups could be distinguished gathering the remaining species as result of the separation of the V3 rDNA amplicons in DGGE. Furthermore, the combination of the results obtained by PCR-DGGE and ISR-PCR analyses allowed a clear differentiation of all the staphylococcal species analysed, with exception of the pairs S. equorum-S. cohnii and S. carnosus-S. schleiferi. The suitability of both molecular techniques and of the combination their results for the identification of staphylococci was validated analysing partial nucleotide sequence of the 16S rDNA of a representative number of wild strains.
Journal of Food Engineering, 2006
Letters in Applied Microbiology, 1994
One hundred and twenty-five isolates of Micrococcaceae from Italian salami were tested for antago... more One hundred and twenty-five isolates of Micrococcaceae from Italian salami were tested for antagonistic activities against Listeria monocytogenes. Four isolates, identified as Staphylococcus xylosus, inhibited the growth of all five strains of L. monocytogenes tested. The antagonistic substances produced by strains 39A and 41A were inactivated by some proteases, whereas those from strains 1E and 27E were inactivated only by esterase and lipase. They are neither bacteriophages, nor lytic enzymes like lysostaphin.
Fems Microbiology Letters, 1996
Meat Science, 2004
A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fer... more A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fermented sausages after enrichment in MRS broth at pH 2.5 followed by bile salt stressing (1% bile salts w/v). One hundred and fifty acid- and bile-resistant strains were selected, avoiding preliminary and time-consuming isolation steps. Strains were further characterized for survival at pH 2.5 for 3 h in phosphate-buffered saline and for growth in the presence of 0.3% bile salts with and without pre-exposure at low pH. Twenty-eight strains showed a survival >80% at pH 2.5 for 3 h; moreover, most of the strains were able to grow in the presence of 0.3% bile salts. Low pH and bile resistance was shown to be dependent on both the species, identified by phenotypic and molecular methods, and the strain tested. This is the first report on the direct selection of potentially probiotic lactobacilli from dry fermented sausages. Technologically interesting strains may be used in the future as probiotic starter cultures for novel fermented sausage manufacture.
Journal of Applied Microbiology, 2004
Journal of Applied Microbiology, 1997
International Journal of Food Microbiology, 1995
Streptococcus thermophilus 347 isolated from yogurt produces a bacteriocin referred as thermophil... more Streptococcus thermophilus 347 isolated from yogurt produces a bacteriocin referred as thermophilin 347. The bacteriocin was evidenced in the neutralized, filtered and catalase treated culture supernatant fluid of the producer strain. After partial purification, thermophilin 347 exhibited a bactericidal effect against Listeria monocytogenes and several closely related lactic acid bacteria. The activity of thermophilin 347 was lost after protease treatment but was maintained after heating at 100 degrees C for 1 h; after autoclaving at 121 degrees C for 15 min the activity was reduced by 50%. SDS-PAGE of partially purified thermophilin 347 was used to detect bacteriocin activity corresponding to an apparent molecular mass between 2.5 and 6.2 KDa.
International Journal of Food Microbiology, 2001
In this work we studied using different molecular methods the population dynamics of nisin-produc... more In this work we studied using different molecular methods the population dynamics of nisin-producing organisms and the persistence of such organisms within a complex ecosystem, 'Fior di latte' cheese, a traditional high-moisture pasta filata cheese. Using the primers targeting the eubacterial 16S-23S rRNA spacer region, together with those amplifying the nisA or nisZ gene, we were able to provide a rapid species identification of the isolates. Inhibitors of Lactococcus lactis subsp. lactis DSM 20481T used as indicator occurred during the whole process of cheese manufacture as a significant part of lactic microflora; however, only 12 among 109 isolates of bacteriocin producers were nisin producers. Amplification of the nisA or nisZ gene, using DNA extracted directly from dairy samples as templates, showed that the nisin structural gene was detected during cheese-making from milk samples up to the end of curd ripening but not in the final cheese. In order to monitor nisin-producing strains during cheese manufacturing, the 12 Lactococcus lactis nis+ strains were analysed by low frequency restriction fragment and PFGE. Nine isolates among the 12 nisin-producers exhibited an unique and distinct DNA banding pattern and are considered to be genetically diverse. The other three isolates from curd after ripening showed the same restriction pattern and could be the same strain. In fact, it was also isolated 2 months after the first analysis of cheese-making of 'Fior di latte'.
Journal of Applied Microbiology, 2004
Applied and Environmental Microbiology, 2000
Meat Science, 2004
The aims of this study were to characterize the population of Micrococcaceae in different types o... more The aims of this study were to characterize the population of Micrococcaceae in different types of fermented sausages of Southern Italy and to determine the technological properties of Staphylococcus strains in order to evaluate the suitability of selected strains as starter cultures in the processing of dry fermented pork sausages. Ninety-six strains were studied to evaluate nitrate reductase, proteolytic, lipolytic and antioxidant activities as well as growth ability at different temperatures, pH's and NaCl concentrations. All the strains were classified as Staphylococcus except for one isolate assigned to Kocuria spp. The species most often isolated were S. saprophyticus, S. xylosus and S. equorum, although they were not equally distributed within the different sausages. Other species isolated were, in descending order of abundance, S. succinus, S. warneri, S. lentus, S. vitulus, S. pasteuri, S. epidermidis, and S. haemolyticus. In general, the S. xylosus strains exhibited the best technological properties that would make them eligible as good starter cultures for fermented meat products. However, strains belonging to other species also showed good technological properties. Finally, all strains grew at 10, 15 and 20 °C, in the presence of 10% and 15% of NaCl and at pH 5.0 and 5.5. The results showed that it is possible to formulate a broad variety of staphylococcal starter cultures, adaptable to different technological conditions and sausage manufacture practices.
Applied and Environmental Microbiology, 2006
Applied and Environmental Microbiology, 2001
Journal of Applied Microbiology, 2004
Journal of Applied Microbiology, 1993
F. VILLANI, G. SALZANO, E. SORRENTINO, O. PEPE, P. MARINO AND S. COPPOLA. 1993. Enterococcus faec... more F. VILLANI, G. SALZANO, E. SORRENTINO, O. PEPE, P. MARINO AND S. COPPOLA. 1993. Enterococcus faecalis 226, isolated from natural whey cultures utilized as starters in the manufacture of mozzarella cheese from water-buffalo milk, produces a bacteriocin designated enterocin 226NWC. The bacteriocin was isolated from culture supernatant fluids of the producer strain and was active against strains of the same species and Listeria monocytogenes, but not against useful lactic acid bacteria. Enterocin 226NWC is a protein with an apparent molecular weight of about 5800; it is relatively heat-stable and has a bactericidal mode of action. Listeria monocytogenes, growing in the presence of the enterocin 226NWC producer strain in broth and in reconstituted skim milk, was inhibited.
Systematic and Applied Microbiology, 2003
Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (PCR-D... more Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (PCR-DGGE) and 16S-23S rDNA intergenic spacer region polymorphism (ISR-PCR) analyses were tested as tool for differentiation of staphylococcal strains commonly isolated from fermented sausages. Variable V3 regions of 25 staphylococcal reference strains and 96 wild strains of species belonging to the genera Staphylococcus, Micrococcus and Kocuria were analyzed. PCR-DGGE profiles obtained were species-specific for S. sciuri, S. haemolyticus, S. hominis, S. auricularis, S. condimenti, S. kloosi, S. vitulus, S. succinus, S. pasteuri, S. capitis and S. (Macrococcus) caseolyticus. Moreover, 7 groups could be distinguished gathering the remaining species as result of the separation of the V3 rDNA amplicons in DGGE. Furthermore, the combination of the results obtained by PCR-DGGE and ISR-PCR analyses allowed a clear differentiation of all the staphylococcal species analysed, with exception of the pairs S. equorum-S. cohnii and S. carnosus-S. schleiferi. The suitability of both molecular techniques and of the combination their results for the identification of staphylococci was validated analysing partial nucleotide sequence of the 16S rDNA of a representative number of wild strains.
Journal of Food Engineering, 2006
Letters in Applied Microbiology, 1994
One hundred and twenty-five isolates of Micrococcaceae from Italian salami were tested for antago... more One hundred and twenty-five isolates of Micrococcaceae from Italian salami were tested for antagonistic activities against Listeria monocytogenes. Four isolates, identified as Staphylococcus xylosus, inhibited the growth of all five strains of L. monocytogenes tested. The antagonistic substances produced by strains 39A and 41A were inactivated by some proteases, whereas those from strains 1E and 27E were inactivated only by esterase and lipase. They are neither bacteriophages, nor lytic enzymes like lysostaphin.
Fems Microbiology Letters, 1996