Cytotoxic activity induced by Escherichia coli isolated from drinking water.

¹Ribeiro, D.A; ¹Martins, L.M.; ²Furumura M.T.; ²Lanna, M.C.S. and ¹Yano. T.

1 Depto. Mirobiologia e Imunologia, IB, UNICAMP, Campinas-SP. 2 Lab. Microbiologia UFOP, Ouro Preto-MG

Escherichia coli  is one of the most important animal and human enterophatogen. Twenty one E. coli were isolated from drinking water at Ouro Preto city, MG, with the objetive of verify some virulence factors. E. coli culture supernatants  were obtained by growing in 5 mL BHI medium, at 37º C with shaking (150 rpm), for about 5 h. Then 25 mL of Mitomycin C (0,2 mg/ml) was added to the cultures and the remained for 18 h. Afterwards the centrifugations was done (12,000 x g by 30 min) at 4ºC and supernatant collected and kept at – 20ºC until biological assays. The detection of cytotoxic activities was performed on monolayer Vero and HeLa cells. The culture supernatants were applied on cells culture and biological effects analysed during a periods of 48 on inverted optical microscopy (Nikon Instruments, Japan). PCR analysis showed presence of LT genes to 14% (3) and its was confirmed for cytophaticeffects on Vero cells. Twenty three percent (5) of our isolates caused cellular rounding, death and detachment of Vero cells. The presence or strong cytoplasmic vacuolation was verifyed in 14% (3) and these same isolates caused apoptosis which was proved by  the TUNEL and Feulgen reactions. No cytotoxic effect was observed on HeLa cells. We will be studing and characterizing these different biological effects caused by these cytotoxins to correlate to human enteropathology.

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