Isolation and Characterization of Antagonistic Bacillus Strains Capable to Degrade Ethylenethiourea Csaba Va ´gvo ¨lgyi • Enik} o Sajben-Nagy • Bettina Bo ´ka • Mo ´nika Vo ¨ro ¨s • Adrienn Berki • Andrea Pala ´gyi • Judit Krisch • Biljana S ˇ krbic ´ • N. Ðuris ˇic ´-Mladenovic ´ • La ´szlo ´ Manczinger Received: 19 September 2012 / Accepted: 15 October 2012 Ó Springer Science+Business Media New York 2012 Abstract In this study, more than 150 bacteria showing antagonistic properties against bacterial and fungal patho- gens of the tomato plant were isolated and characterized. The most efficient agents against these phytopathogenic microorganisms belong to the genus Bacillus: the best biocontrol isolates were representatives of Bacillus subtilis, B. mojavensis and B. amyloliquefaciens species. They intensively produced fengycin or/and surfactin depsipep- tide antibiotics and also proved to be excellent protease secretors. It was proved, that the selected strains were able to use ethylenethiourea (ETU) as sole nitrogen source. These antagonistic and ETU-degrading Bacillus strains can be applied as biocontrol and also as bioremediation agents. Introduction Many phytopathogenic bacteria and fungi attack tomato plants both in seedling (e.g. Rhizoctonia solani, Pyth- ium debaryanum) and in developed foliar state (e.g. Phy- tophthora infestans, Botrytis cinerea, Alternaria solani, Xanthomonas vesicatoria, Pseudomonas syringae pv. tomato, Clavibacter michiganensis). It would be desirable to find an efficient biocontrol approach for preventing the destructive effect of these pathogens. Of the biological control alternatives to chemical pesticides, the applica- tion of non-pathogenic soil bacteria in the rhizosphere is promising. Treatments with these beneficial organisms in many cases were associated with reduced plant diseases in greenhouse and field experiments [20]. These bacteria can antagonize first of all fungal pathogens by competing for niche and nutriments, by producing low-molecular-weight fungitoxic compounds and extracellular lytic enzymes and indirectly, by stimulating the defensive capacities of the host plant. Powerful antifungal metabolites can be syn- thesized by most of the Bacillus strains. It was suggested that antibiotic production by these strains plays a major role in plant disease suppression [12]. Antagonistic bacteria are able to reduce the popula- tion density or disease-causing activities of the pathogens through one or more of the following mechanisms: anti- biosis, competition and hyperparasitism [20, 25]. Among them, hyperparasitism and in some cases antibiosis relies on lytic enzymes capable to degrade of cell walls and membranes of pathogenic fungi and bacteria. First of all, chitinolytic, proteolytic and lipolytic enzymes have been considered important in the biological control of soilborne plant-pathogenic microorganisms [2, 19, 21, 22]. Some of these enzymes, first of all b-1,3-glucanase, chitinases, lipases and proteases could directly promote the inhibi- tion processes, while others, such as cellulases and xylan- ases could help the competition of the bacilli against other rhizosphere microorganisms. Mancozeb is a frequently applied fungicide in vegeta- ble cultures. This compound is very instable and in solu- tion spontaneously decomposes within 2 weeks. However, its spontaneous degradation product, the carcinogenic C. Va ´gvo ¨lgyi  E. Sajben-Nagy  B. Bo ´ka  M. Vo ¨ro ¨s  A. Berki  A. Pala ´gyi  L. Manczinger (&) Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Ko ¨ze ´p fasor 52, Szeged 6726, Hungary e-mail: manczing@bio.u-szeged.hu J. Krisch Faculty of Engineering, Institute of Food Engineering, University of Szeged, Mars te ´r 7, Szeged 6724, Hungary B. S ˇ krbic ´  N. Ðuris ˇic ´-Mladenovic ´ Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia 123 Curr Microbiol DOI 10.1007/s00284-012-0263-8