EFFECTS OF DIFFERENT FACTORS ON BIOFILM FORMATION IN Streptococcus uberis STRAINS

MOLIVA, MELINA VANESA; LASAGNO, M. C.; REINOSO, ELINA B.

CORDOBA

Congreso; XI CONGRESO ARGENTINO DE MICROBIOLOGIA GENERAL; 2015

Streptococcus uberis is one of the main infectious agents responsible for causing mastitis. Previous studies carried out in ourlaboratory showed that S. uberis strains isolated from milk are able to produce biofilm. It is speculate that one of the reasonsbehind the prevalence of S. uberis infections is its ability to form biofilm. This study investigated the influence of different factorsas: lactose (5%), skim milk (0.5%), alpha-casein (3mg/ml), bovine serum albumin (5 mg/ml) and proteases inhibitors as cysteineprotease inhibitor E-64 (1 mM) and metalloprotease inhibitor 1-10 phenantroline (100 M). In addition the stability of S. uberisbiofilm against protease treatment with proteinase K was tested. Thirty two S. uberis strains previously identified andcharacterized for biofilm formation were used. Our study indicated that the substrates skim milk, alpha casein and bovine serumalbumin appear to have a positive effect on its ability to form biofilms. These results suggest that the milk protein composition ofthe host might affect the growth mode of S. uberis and the development of infection, promoting adherence and internalization.On the other way, lactose had no significant effect on the biofilm formation under these conditions. However the effects of thedifferent factors seem to vary between the strains. The treatment of biofilms with proteinase K resulted in complete detachmentof biofilms, suggesting that extracellular proteins play a crucial role in formation of biofilm. E-64 and 1-10 showed to increasebiofilm production in the presence of alpha casein. Our results provide a valuable insight into molecular specificities of thispathogen. Future work will concentrate in associating S. uberis ability to form biofilms in vivo and intramammary infection. Thiswill allow for development of strategies to better manage and prevent mastitis caused by this pathogen.