DUGi

Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant- Associated Bacillus against Phytopathogenic Bacteria

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@268703

The antibacterial activity against bacterial plant pathogens and its relationships with thepresence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin),fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptideproducts have been studied in a collection of 64 strains of Bacillus spp. isolated from plantenvironments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAAandfenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6%iturinsand 79.7% fengycins. The antibacterial activity was very frequent and generally intenseamong the collection of strains because 75% of the isolates were active against at least 6 ofthe 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmedthe presence of two clearly differentiated groups. One group consisted of Bacillus strainsthat showed a strong antibacterial activity, presented several cLPs genes and producedseveral isoforms of cLPs simultaneously, mainly composed of B. subtilisand B. amyloliquefaciens,although the last one was exclusive to this group. Another group was characterizedby strains with very low or none antibacterial activity, that showed one or none of the cLPgenes and produced a few or none of the corresponding cLPs, and was the most heterogenousgroup including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereusandB. thuringiensis, although the last two were exclusive to this group. This work demonstratedthat the antagonistic capacity of plant-associated Bacillusagainst plant pathogenic bacteriais related to the presence of cLP genes and to the production of the corresponding cLPs,and it is mainly associated to the species B. subtilisand B. amyloliquefaciens. Our findingswould help to increase the yield and efficiency of screening methods to obtain candidatestrains to biocontrol agents with a mechanism of action relaying on the production of antimicrobialcLPs

Funding was provided by Programa Nacional de Agricultura y Alimentación (CICYT) (Ref. AGL-2009-13255-C02-01) of the MINECO of Spain, and FP7 KBBE.2013.1.2-04. Ref. 613678. DROPSA project of the European Union. The research group is accredited and supported in part by SGR 2009-0812, 2014 SGR 697 and TECNIO net from Catalonia

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