Publicación: QUORUM SENSING ACTIVITY IN OPHIOSTOMA ULMI: EFFECTS OF FUSEL OILS AND BRANCHED CHAIN AMINO ACIDS ON YEAST-MYCELIAL DIMORPHISM
Fecha
2012
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JOURNAL OF APPLIED MICROBIOLOGY
Resumen
FOR OPHIOSTOMA (CERATOCYSTIS) ULMI, THE ABILITY TO UNDERGO MORPHOLOGICAL CHANGE IS A CRUCIAL FACTOR FOR ITS VIRULENCE. TO GAIN AN UNDERSTANDING OF QUORUM-SENSING ACTIVITY IN O. ULMI AS IT RELATES TO YEAST-MYCELIUM DIMORPHISM CONTROL, THIS STUDY EXAMINES THE EFFECTS OF BRANCHED-CHAIN AMINO ACIDS AS WELL AS THEIR FUSEL ALCOHOLS AND FUSEL ACIDS AS QUORUM SENSING MOLECULES.
METHODS AND RESULTS: IN A DEFINED MEDIUM CONTAINING GLUCOSE, PROLINE AND SALTS, O. ULMI GREW AS YEASTS WHEN THE CULTURE WAS INOCULATED WITH A HIGH DENSITY OF SPORES (2 × 10(7) CFU ML(-1) ) AND AS MYCELIA WHEN INOCULATED WITH A LOW SPORE DENSITY (4 × 10(5) CFU ML(-1) ). THE CULTURES DISPLAYING YEAST MORPHOLOGY SECRETED A QUORUM-SENSING FACTOR THAT SHIFTED THE MORPHOLOGY FROM MYCELIA TO YEAST. THIS QUORUM-SENSING MOLECULE WAS LIPOPHILIC AND EXTRACTABLE BY ORGANIC SOLVENTS FROM THE SPENT MEDIUM. USING GC/MS ANALYSIS, IT WAS DETERMINED THAT THE MAJOR COMPOUND IN THE EXTRACT WAS 2-METHYL-1-BUTANOL. A SIMILAR EFFECT WAS OBSERVED WHEN THE BRANCHED-CHAIN AMINO ACIDS (FUSEL ALCOHOL PRECURSORS) WERE USED AS THE NITROGEN SOURCE. E, E-FARNESOL HAD NO EFFECT ON THE MORPHOLOGY OF O. ULMI.
CONCLUSIONS: ADDITION OF THE BRANCHED-CHAIN AMINO ACIDS OR ONE OF THE COMPOUNDS DETECTED IN THE SPENT MEDIUM, 2-METHYL-1-BUTANOL OR 4-HYDROXYPHENYLACETIC ACID, OR METHYLVALERIC ACID, DECREASED GERM TUBE FORMATION BY MORE THAN 50%, THUS DEMONSTRATING A QUORUM SENSING MOLECULE BEHAVIOUR IN O. ULMI CULTURES.
SIGNIFICANCE AND IMPACT OF THE STUDY: THIS STUDY PRESENTS ADVANCES IN THE INVESTIGATION OF DIMORPHISM IN O. ULMI, COMPLEMENTING THE EXISTING SCIENTIFIC BASIS, FOR STUDYING, UNDERSTANDING AND CONTROLLING THIS PHENOMENON.
