Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Item Effect of bovicin HC5 on growth and spore germination of Bacillus cereus and Bacillus thuringiensis isolated from spoiled mango pulp(Journal of Applied Microbiology, 2006-09-27) Carvalho, A.A.T. de; Costa, E.D.; Mantovani, H.C.; Vanetti, M.C.D.Aims: To use bovicin HC5 to inhibit predominant bacteria isolated from spoiled mango pulp.Methods and Results: Bovicin HC5 and nisin were added to brain heart infusion (BHI) medium (40–160 AU ml )1 ) or mango pulp (100 AU ml )1 ) and the growth of Bacillus cereus and Bacillus thuringiensis was monitored. Cultures treated with bovicin HC5 or nisin showed longer lag phases and grew slower in BHI medium. Bovicin HC5 and nisin were bactericidal and showed higher activity in mango pulp at acidic pH values. To determine the effect on spore germination and D values, mango pulp containing bovicin HC5 was inoculated with 10 6 and 10 9 spores per ml )1 , respectively, from each strain tested. Bovicin HC5 reduced the outgrowth of spores from B. cereus and B. thuringiensis, butthermal sensitivity was not affected.Conclusions: Bovicin HC5 was bactericidal against B. cereus and B. thuringien sis isolated from spoiled mango pulp.Significance and Impact of the Study: Bacillus cereus and B. thuringiensis had not been previously isolated from spoiled mango pulp and bovicin HC5 has the potential to inhibit such bacteria in fruit pulps.Item Inhibition of Listeria monocytogenes by a lactic acid bacterium isolated from Italian salami(Food Microbiology, 2005-07-18) Carvalho, Ana Andréa Teixeira de; Paula, Rosinéa Aparecida de; Mantovani, Hilário C.; Moraes, Célia Alencar deListeria monocytogenes is an opportunistic psychrotroph foodborne pathogen that has been used as a model organism to study the efficacy of many different preservation methods. This work aimed to test the antilisterial activity of lactic acid bacteria isolated from Italian salami and study the development of resistance. Isolates were obtained from naturally fermented Italian salami and cultures that retained activity in the supernatants after pH neutralization and catalase treatment were further characterized. The isolate showing highest inhibitory activity (PD 6.9) was tested for sensibility to proteases, heat and pH. To evaluate if resistance developed, sensitive strains were transferred with sub-lethal doses of the partially purified inhibitory substance and then inoculated into media containing higher doses of the extract. Isolate PD 6.9 inhibited several L. monocytogenes strains obtained from different origins and retained its activity over a wide range of pH and temperature. When increasing concentrations (10–100 AU ml−1) of the partially purified inhibitory substance were added to culture media, growth of L. monocytogenes did not occur even after 12 h of incubation. Cultures of Listeria that were transferred with sub-lethal doses (10 AU ml−1) of the partially purified inhibitory substance could resist higher doses of the extract (50 AU ml−1), but were inhibited when the concentration was further increased (100 AU ml−1). These results indicate that isolate PD 6.9 could potentially be used as a bioprotective culture for salami fermentation.