Antimicrobial Activity of Bacillus sp. Natural Isolates and Their Potential Use in the Biocontrol of Phytopathogenic Bacteria
Tanja Berić1, Milan Kojić2, Slaviša Stanković1, Ljubiša Topisirović2, Giuliano Degrassi3, Michael Myers3, Vittorio Venturi3 and Djordje Fira1,2*
1Faculty of Biology, University of Belgrade, Studentski trg 16, RS-11010 Belgrade, Serbia
2Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, P.O. Box 23, RS-11010 Belgrade, Serbia
3International Centre for Genetic Engineering and Biotechnology, AREA Science Park, Padriciano 99, IT-34149 Trieste, Italy
Article history:
Received January 25, 2011
Accepted August 31, 2011
Key words:
Bacillus sp., Xanthomonas oryzae pv. oryzae, lipopeptides, iturin, bacteriocin
Summary:
Screening of 203 Bacillus sp. natural isolates for antimicrobial activity against phytopathogenic bacteria showed that 127 tested strains inhibit at least one sensitive strain, which illustrates their potential use as biocontrol agents. Among them, 104 isolates showed significant antagonism against Xanthomonas oryzae pv. oryzae, and only one of these (VPS50.2) synthesizes bacteriocin. An additional screening tested whether 51 isolates contained genes involved in the biosynthesis of lipopeptides of the iturin and surfactin classes. Results show that 33 isolates harbour the operon for iturin biosynthesis, and six of them carry the sfp gene, responsible for the biosynthesis of surfactin. Lipopeptide purification from the supernatant of isolate SS12.9 (identified as B. subtilis or B. amyloliquefaciens) was performed using ethyl acetate extraction, ultrafiltration and reversed phase HPLC. Mass spectrometry analysis confirmed that isolate SS12.9 produces a substance of the iturin class with potential for biocontrol of X. oryzae pv. oryzae.
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