RESUMO
This study was conducted to investigate the relationship between pH and the toxicity of sulfur dioxide against homo- and hetero-lactic acid bacteria isolated from American acidic wines. Malolactic fermentation was found to be growth-associated in homo- and hetero-lactic strains. The pH of CBB broth had an insignificant effect on the specific death rate of these strains; the concentration of molecular sulfur dioxide had a great effect on the specific death rate and malate degradation. Laboratory or freshly isolated strains were exposed to various concentrations of free sulfur dioxide at pH 3.8 and 3.4. At pH 3.4, sulfur dioxide was more effective against lactic acid bacteria than at pH 3.8 since more was present as molecular sulfur dioxide and causing an increase in the specific death rate. Pediococcus strain BB was more resistant to sulfur dioxide than those hetero-lactic fermentation strains such as Leuconostoc oenos PSU-1 and ML-34. The effect of sulfur dioxide concentration on the viability of L. oenes ML-34, PSU-1, and Pediococcus strain BB appeared to be biphasic. No or little L-malic acid was degraded when the homo- and hetero-fermentative strains were killed by sulfur dioxide.
Assuntos
Lactatos/metabolismo , Leuconostoc/efeitos dos fármacos , Pediococcus/efeitos dos fármacos , Dióxido de Enxofre/farmacologia , Vinho/microbiologia , Concentração de Íons de Hidrogênio , Ácido Láctico , Leuconostoc/metabolismo , Malatos/metabolismo , Testes de Sensibilidade Microbiana , Pediococcus/metabolismoRESUMO
The effect of IRNA therapy in a polyoma-induced fibrosarcoma of C3H mice has been studied. Although a protocol that transferred in vitro cytotoxicity was used, no reduction in incidence of tumors, tumor size, or survival was demonstrated. In one experiment, enhancement of tumor growth occurred. It is concluded that cytotoxicity does not reflect in vivo changes and that therapeutic trials of IRNA are premature.
