Endophytic Fungi from Sorghum bicolor (L.) Moench: Influence of Genotypes and Crop Systems and Evaluation of Antimicrobial Activity

Abstract

Endophytic fungi (EF) colonize plant tissues without causing damage; this relationship brings benefits to both, including a greater resistance to environmental stresses, but the influence of genotypes and culture system in endophytic community is still unraveled. Thus, this work aimed to study EF from Sorghum bicolor and correlate to its genotypes submitted to different culture systems; their potential to produce antimicrobial compounds was also evaluated. To optimize the production of metabolites, four isolates were submitted to liquid medium and the crude extracts of different culture times were analyzed. EF of leaves of Qualimax and SF15 genotypes were isolated after superficial disinfection. Fungal identification was made using classical taxonomy. As results, the traditional system presented the lowest number EF isolates, while the minimum system showed the highest. The genera Aspergillus, Fusarium, Penicillium, Cladosporium, Curvularia and Syncephalastrum were found; Aspergillus spp. was pointed out as a predominant endophyte of genotype Qualimax. Among the 25 endophytes submitted antimicrobial activity assay in solid medium, 21 presented antibacterial activity against at least one bacterium with the highest inhibition zone of 29.3 mm of diameter against Staphylococcus aureus. All EF submitted to liquid medium kept the capacity to produce antibacterial metabolites. In conclusion, regardless of genotype and culture system, sorghum is colonized by different EF, mainly Aspergillus spp. EF from leaves of S. bicolor produce antibacterial compounds and their biotechnological applications can be explored in future.