INVESTIGADORES
NIETO PEÑALVER Carlos Gabriel
congresos y reuniones científicas
Título:
DEGRADATION OF BACTERIAL QUORUM SENSING MOLECULES BY Rhodotorula sp.
Autor/es:
CARLOS G. NIETO PEÑALVER; ANA CAROLINA LEGUINA ; GIULIANO DEGRASSI; VERÓNICA P. IRAZUSTA; VITTORIO VENTURI; LUCÍA I. CASTELLANO DE FIGUEROA
Lugar:
Rosario
Reunión:
Congreso; IX CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2013
Institución organizadora:
Sociedad Argentina de Microbiología General
Resumen:
Microorganisms can regulate their physiology in a cell concentration-dependent manner through the production of small
regulatory molecules, the concentration of which is directly related to the density of the population. This phenomenon, known as
quorum sensing (QS), has largely been described in both Gram positive and negative bacteria. Since it has been related to the
control of the production of virulence and colonization factors, the QS regulatory system has also been studied as a putative
control mechanism for pathogenic microorganisms. Lactonases and acylases inactivate the QS systems of Gram negative
bacteria through the hydrolysis of N-acyl homoserine lactones (AHLs), the main signal molecules produced by this group of
microorganisms. These enzymes have been isolated from bacteria belonging to the genera of Bacillus, Pseudomonas,
Streptomyces, Comomonas, and Ralstonia, among others. In this work evidence presented shows that Rhodotorula sp.,
pigmented yeast previously isolated from a filter plant of a copper mine in the province of Tucumán, Argentina, has the capacity
of inactivating a wide range of AHLs. Rhodotorula sp. was cultured in YM medium in the presence of 1μM of the following
AHLs: C6-HSL, C8-HSL, C10-HSL, C12-HSL, 3-oxo-C6-HSL, 3-oxo-C8-HSL, 3-oxo-C10-HSL and 3-oxo-C12-HSL. After
incubation, the remaining AHLs in the supernatants were analyzed with bioassays in plates developed with the biosensors
Chromobacterium violaceum CV026, C. violaceum Vir07 and Agrobacterium tumefaciens NTL4 (pCF218) (pCF372). Results
show that Rhodotorula sp. could completely inactivate AHLs with short (C6- and C8-HSLs) and long acyl chains (10- and
C12-HSLs). In addition, this pigmented yeast presented AHL-inactivating activity against substituted (3-oxo-derivative) and
unsubstituted signal molecules. In contrast to acylases, lactonases hydrolyze AHLs through the opening of the lactone ring that
is present in all this type of molecules. The proteinaceous nature of the AHL-inactivating activity could be established after
incubating a Rhodotorula sp. protein extract with pronase. To study the putative mechanism of signal inactivation by
Rhodotorula sp., supernatants were acidified with HCl in order to permit the closure of the lactone ring, and analyzed as
described before. The partial recovery of the regulatory activity in the samples suggests that the yeast hydrolyze AHLs through
the production of one or more lactonases. Taking together, these results show the potential of Rhodotorula sp. to produce
enzymes that interfere with quorum sensing systems of pathogenic bacteria.