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This study is focused on the concentration of fermented broth from Phoma sp. to increase its herbicidal activity. For this purpose, biomolecules produced by submerged fermentation using Phoma sp. were concentrated by hollow fiber microfiltration membranes. The membrane feed was separated into two streams (retentate and permeate) and the crude broth was concentrated to 10, 30, 50, 70 and 90% (relative to the initial volume). The retentate samples were submitted to bioassays (triplicate) for evaluating their phytotoxic effects on five young leaves of species of Cucumis sativus and also on pre-emergence of weeds as Bidens pilosa and Amaranthus retroflexus. The highest herbicidal activity was 80.7% obtained for a concentration of 30% in the retentate fraction. At this condition, the bioherbicide presented severe damage symptoms on the detached leaves of Cucumis sativus if compared to the crude fermented broth. In the pre-emergence of B. pilosa and A. retroflexus, 100% control was obtained for assays performed in a germination chamber. For greenhouse assays using the substrate, the control rate of A. retroflexus was dependent of concentration of bioherbicide. The promising results achieved in the research with membrane separation process allow us to propose and develop further studies for evaluating this technology in the concentration of other metabolites produced by fermentation which also have bioherbicidal activity.

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Fungi are considered the most damaging microorganisms in agriculture. The indiscriminate use of chemical treatments in agricultural products causes the development of pest resistance and affects human health. An alternative to synthetic fungicides is the use of natural products such as plant extracts for the management of fungal diseases in plants. Extracts from different parts of Lupinus albescens (roots, stalks, leaves, and flowers) were obtained by extraction using supercritical carbon dioxide (CO) or compressed liquefied petroleum gas (LPG). Thereafter, the antioxidant activity of each extract was measured, and the antifungal activity in vitro of extracts was evaluated against Fusarium oxysporum and Fusarium verticillioides. For a concentration of 5000 mg/L, the half maximal inhibitory concentration (IC) ranged from 29.25 μg/mL to 192.96 μg/mL. Antifungal tests showed that all matrices presented inhibitory effect against both fungi tested. The extracts obtained from roots by CO and LPG presented 70.1% and 65.1% inhibition against F. oxysporum, and 67.8% and 61.2% inhibition against F. verticillioides, respectively. These results suggest that the extracts obtained from L. albescens by extractions using supercritical CO and compressed LPG might be a potential source of antioxidants and natural fungicides.

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Antioxidant compounds were produced from submerged fermentation using Botryosphaeria dothidea. Sonication times (1-15 min) and agitations (0-150 rpm) applied to different fermentation phases (2-7 days) were evaluated for their effect on the broth antioxidant activity. In approximately 70% of assays performed with ultrasound, the antioxidant activity of the broth containing exocellular metabolites was higher than the control (without sonication), reaching a maximum value of 96%. The solid fraction (biomass after supernatant removal) corresponding to the best assay of antioxidant activity was submitted to extractions with water, ethanol or ethyl acetate to recover intracellular metabolites. The yields of extracts were 3.7 ± 2.6 wt %, 20.6 ± 3.9 wt % and 32.0 ± 4.2 wt % for ethyl acetate, ethanol and water, respectively. The use of ethanol could provide a larger number of compounds such as pentadecanoic acid, ergosta-5,8,22-trien-3-ol, and 1,4-diaza-2,5-dioxobicyclo [4.3.0] nonane. Both the supernatant and solid fractions revealed some bioactive compounds with promising antioxidant activity with the potential to replace some synthetic antioxidants.