Characterisation of the Antibiotic Profile of Lysobacter capsici AZ78, an Effective Biological Control Agent of Plant Pathogenic Microorganisms

Francesca Brescia, Anthi Vlassi, Ana Bejarano, Bernard Seidl, Martina Marchetti-Deschmann, Rainer Schuhmacher and Gerardo Puopolo

INFORMATIVE ABSTRACT -  Lysobacter capsici AZ78 is an effective biological control agent of plant pathogenic microorganisms. This abstract lead to analyse its antibiotic profile.

Lysobacter capsiciAZ78 is a biocontrol rhizobacterium able to inhibit a vast array of plant pathogenic oomycetes, cause of many diseases, and Gram-positive bacteria due to the release of a relevant number  of antimicrobial secondary metabolites.

To better understand the benefits of this ability, it’s useful to remind that pathogenic oomycetes could cause: seedling blights, damping-off, root rots, foliar blights and downy mildews. Some notable diseases are the late blight of potato, downy mildew of grape vine, sudden oak death, and root and stem rot of soybean. Gram-positive bacteria are rather defined as those that remain blue or purple after having undergone Gram staining when seen through an optical microscope.

Secondary metabolites are biologically active small molecules that are not required for viability but which provide a competitive advantage to the producing organism. The bacterial secondary metabolites are a source of many of the antibiotics, chemotherapeutic drugs, immune suppressants and other medicines.

The study, through a work of dissection of AZ78 metabolome using a combination of MALDI-qTOFMSI and UHPLC-HRMS/M, determined the main secondary metabolites involved in the ability of AZ78 to control and inhibit the oomycetes and Gram-positive bacteria. The conclusion that this metabolites belongs to the families of 2,5-diketopiperazines and cyclic depsipeptide could help the future development of this bacterial strain as the active ingredient of a microbial biopesticide that might contribute to a reduction in the chemical input in agriculture.