Use of Isotope Ratio Mass Spectrometry (IRMS) for the study of trophic interaction among pathogen and antagonists

The soil microbial component, involved in biological control mechanisms of phytopathogens, constitutes a class of organisms called bio control agents (BCAs). Considering the difficult to study the active interaction (direct parasitism or active assimilation of metabolites/degradation products), we can overcome this problem using labeled microorganisms by stable isotopes. Labeled microorganisms by 13C isotope can be observed in the environment and, if they are plundered, the labeled residues are detectable into their predator by Isotope Ratio Mass Spectrometry (IRMS) analysis. In this study we set the protocols for the detection of active degradators of Armillaria mellea, the causal agents of root rots of several woody plants. Two different microorganisms (Trichoderma atroviride strain SC1 and Pseudomonas fluorescens strain Pf-5) were tested to identify their ability in the active degradation of pathogen.