Abstract One hundred fifty fungal strains were isolated from the Pampa biome for production of polyunsaturated fatty acids (PUFA). Microbial oil was produced by submerged cultivation at 120 rpm, 28 ºC for 7 days. Seven strains showed the best results for lipids accumulation, and they were selected in order to evaluate the influence of the temperature (15 and 28 ºC) on the lipid production and profile. The fungus Nigrospora sp. produced the highest lipid level: at 28 ºC were produced 11.28% of lipids and 51.94% of PUFA and at 15 ºC were produced 6.02% of lipids and 42.39% of PUFA. Plackett Burman design was performed to investigate the main effects of the temperature (15-25 ºC), pH (4.0-6.0), agitation (120-200 rpm), corn steep liquor (5-15% (v/v)) and sucrose concentrations (60-180 g L-1). The highest PUFA production (55.75%) was observed at the lowest temperatures (15 ºC), whereas the maximum lipid production was 5.54% at 25 ºC.

Abstract Production of a bioherbicide for biological control of weeds requires a series of steps, from selection of a suitable microbial strain to final formulation. Thus, this study aimed to select fungi for production of secondary metabolites with herbicidal activity using biological resources of the Brazilian Pampa biome. Phytopathogenic fungi were isolated from infected tissues of weeds in the Pampa biome. A liquid synthetic culture medium was used for production of metabolites. The phytotoxicity of fungal metabolites was assessed via biological tests using the plant Cucumis sativus L., and the most promising strain was identified by molecular analysis. Thirty-nine fungi were isolated, and 28 presented some phytotoxic symptoms against the target plant. Fungus VP51 belonging to the genus Diaporthe showed the most pronounced herbicidal activity. The Brazilian Pampa biome is a potential resource for the development of new and sustainable chemical compounds for modern agriculture.