Production of volatile compounds and lipopeptides as antagonistic mechanisms of two Bacillus strains towards phytopathogenic fungi

Phytopathogenic fungi are one of the main causes of diseases that affect agricultural production. For their control, in recent years, biological alternatives have been developed, such as the use of antagonistic microorganisms that produce inhibitory molecules towards these fungi, exerting a biocontrol effect. In the present study, Bacillus licheniformis Q19 and Bacillus subtilis Q20 strains were characterized for their ability to inhibit in vitro the mycelial growth of Rhizoctonia solani, Fusarium oxysporum, Sclerotium rolfsii, Colletotrichum gloesporoides and Phytophthora spp. The results of dual cultures show that only Q20 inhibited the pathogens in a range from 33.3 to 50.6 %, being A. alternata who presented the greatest inhibition. A positive test for hemolysis, which is related to the lipopeptide production, indicates that these molecules could probably be involved in the fungal inhibition. Later, assays in plates overlapping, where the study microorganisms are not in the same culture médium, showed that Q19 and Q20 produce volatile compunds, capable of inhibiting A. alternata and S. rolfsii by 72.4 and 56.3 %, respectively. In conclusion, Q19 and Q20 produce lipopeptides and/or volatile compounds with activity against phythopathogenic fungi as biocontrol mechanisms.