RESUMO
The structure and function of the intestinal epithelium is briefly described, with the principal mechanisms involved in diarrhea. Human enteric viruses and probiotics are presented. We then review how probiotic bacteria could interfere with virus-induced pathology, we present our own view and describe specific interactions that would be valuable targets for future studies.
Assuntos
Diarreia/prevenção & controle , Diarreia/terapia , Lactobacillus/crescimento & desenvolvimento , Probióticos/uso terapêutico , Viroses/prevenção & controle , Viroses/terapia , Pré-Escolar , Diarreia/virologia , Células HT29 , Humanos , Mucosa Intestinal/microbiologia , Mucosa Intestinal/virologia , Lactobacillus/classificação , Probióticos/administração & dosagem , Rotavirus/crescimento & desenvolvimento , Rotavirus/patogenicidade , Infecções por Rotavirus/prevenção & controle , Infecções por Rotavirus/terapia , Infecções por Rotavirus/virologia , Viroses/virologia , Vírus/crescimento & desenvolvimento , Vírus/patogenicidadeRESUMO
A strain that efficiently degraded methyl tert-butyl ether (MTBE) was obtained by initial selection on the recalcitrant compound tert-butyl alcohol (TBA). This strain, a gram-positive methylotrophic bacterium identified as Mycobacterium austroafricanum IFP 2012, was also able to degrade tert-amyl methyl ether and tert-amyl alcohol. Ethyl tert-butyl ether was weakly degraded. tert-Butyl formate and 2-hydroxy isobutyrate (HIBA), two intermediates in the MTBE catabolism pathway, were detected during growth on MTBE. A positive effect of Co2+ during growth of M. austroafricanum IFP 2012 on HIBA was demonstrated. The specific rate of MTBE degradation was 0.6 mmol/h/g (dry weight) of cells, and the biomass yield on MTBE was 0.44 g (dry weight) per g of MTBE. MTBE, TBA, and HIBA degradation activities were induced by MTBE and TBA, and TBA was a good inducer. Involvement of at least one monooxygenase during degradation of MTBE and TBA was shown by (i) the requirement for oxygen, (ii) the production of propylene epoxide from propylene by MTBE- or TBA- grown cells, and (iii) the inhibition of MTBE or TBA degradation and of propylene epoxide production by acetylene. No cytochrome P-450 was detected in MTBE- or TBA-grown cells. Similar protein profiles were obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude extracts from MTBE- and TBA-grown cells. Among the polypeptides induced by these substrates, two polypeptides (66 and 27 kDa) exhibited strong similarities with known oxidoreductases.