Navegando por Autor "Carvalho, A.A.T. de"
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Item Bactericidal effect of bovicin HC5 and nisin against Clostridium tyrobutyricum isolated from spoiled mango pulp(Letters in Applied Microbiology, 2007-04-19) Carvalho, A.A.T. de; Mantovani, H.C.; Vanetti, M.C.D.To test the effect of bovicin HC5 – a bacteriocin from Streptococcus bovis HC5 – against the strains of Clostridium tyrobutyricum isolated from canned spoiled mango pulp. Bovicin HC5 [40–160 arbitrary unit (AU) ml−1] reduced the specific growth rate and increased the lag phase duration of the bacterial isolates inoculated in brain heart infusion media at 30°C. The inhibitory activity of bovicin HC5 (100 AU ml−1) in mango pulp was bactericidal and more pronounced at acidic conditions. When C. tyrobutyricum was inoculated into mango pulp with bovicin HC5, gas production was not observed. Cultures that were successively transferred in the presence of sublethal doses of bovicin HC5 did not become resistant. The addition of bovicin HC5 to mango pulp might be effective in preventing deterioration by spoilage bacteria.Item Bovicin HC5 reduces thermal resistance of Alicyclobacillus acidoterrestris in acidic mango pulp(Journal of Applied Microbiology, 2008-01-24) Carvalho, A.A.T. de; Vanetti, M.C.D.; Mantovani, H.C.To test the effect of bovicin HC5 against vegetative cells and endospores of Alicyclobacillus acidoterrestris DSMZ 2498 in synthetic media and in acidic mango pulp. Alicyclobacillus acidoterrestris was grown in synthetic medium at 40°C and pH 4·0. The effect on vegetative cells was assayed by adding bovicin HC5 to synthetic medium (40–160 AU ml−1) or to mango pulp (100 AU ml−1) at various pH values and determining the effect on growth (OD600nm) and viable cell number, respectively. The effect of bovicin HC5 on spore germination and thermal sensitivity of A. acidoterrestris was tested in mango pulp (pH 4·0) containing 80 AU ml−1 of bovicin HC5. Bovicin HC5 was bactericidal against vegetative cells of A. acidoterrestris at different pH values and showed sporicidal activity against endospores of this bacterium. When spores of A. acidoterrestris were heat treated in the presence of bovicin HC5, D-values decreased 77% to 95% compared to untreated controls at temperatures ranging from 80 to 95°C. Bovicin HC5 was bactericidal and sporicidal against A. acidoterrestrsi DSMZ 2498.These results indicated that bovicin HC5 has potential to prevent spoilage of acidic fruit juices by thermocidophilic spore-forming bacteria.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.