Antifungal activity of indigenous bacillus sp. isolate Q3 against marshmallow mycobiota

Abstract

Marshmallow is a host of a number of saprophytic and parasitic fungi in Serbia. The seeds of marshmallow are contaminated with fungi from different genera, especially Alternaria and Fusarium, which significantly reduced seed germination and caused seedling decay. In this study we investigate antagnonism of indigenous Bacillus sp. isolate Q3 against marshmallow mycopopulation. Bacillus sp. Q3 was isolated from maize rhizosphere, characterized by polyphasic approch and tested for plant growth promoting treats. Bacillus sp. Q3 produced antifungal metabolites with growth inhibition activity against numerous fungi in dual culture: 61.8% of Alternaria alternata, 74.8% of Myrothecium verrucaria and 33.6% of Sclerotinia sclerotiorum. That effect could be caused by different antifungal metabolites including siderophores, hydrolytic enzymes, organic acids and indole acetic acid (IAA). Suppression of natural marshmallow seed infection by Q3 isolate was observed. The seeds were immersed in different concentrations of bacterial suspension during 2h and their infections by phytopathogenic fungi were estimated. The results showed significant reduction of seed infection by Alternaria spp. The presented results indicate possible application of this isolate as promising biological agent for control of marshmallow seed pathogenic fungi.Beli slez gajen u Srbiji je domacin mnogim saprofitnim i parazitskim gljivama. Seme je zarazeno gljivama iz razlicitih rodova, narocito Alternaria i Fusarium, ko je znacajno redukuju klijavost semena i izazivaju susenje. U ovom radu ispitivan je antagonizam autohtone bakterije Bacillus sp. izolata Q3 i mikopopulacije belog sleza. Bacillus sp. Q3 je izolovan iz rizosfere kukuruza, karakterizacija je izvrsena polifaznom metodologijom i testirane su osobine odgovorne za stimulaciju rasta biljaka. Bacillus sp. Q3 produkuje antifungalne metabolite sa izrazenom aktivnoscu protiv fitopatogenih gljiva sa razlicitim procentom inhibicije rasta u dvojnoj kulturi: 61.75% kod Alternaria alternata, 74.80% kod Myrothecium verrucaria i 33.63% kod Sclerotinia sclerotiorum. Ovaj efekat je posledica produkcije razlicitih antifungalnih metabolita, ukljucujuci siderofore, hidroliticke enzime, organske kiseline i indolsircetnu kiselinu (IAA). Ustanovljeno je suzbijanje prirodne infekcije semena belog sleza primenom izolata Bacillus Q3. Semena su potapana u razlicite koncentracije bakterijske suspenzije tokom 2 h i pracen je stepen infekcije fitopatogenim gljivama. Rezultati su pokazali znacajan stepen redukcije infekcije semena belog sleza gljivom Alternaria spp. Ovi rezultati ukazuju na mogucu primenu ovog izolata kao potentnog bioloskog agensa za kontrolu infekcije semena belog sleza fitopatogenim gljivama.