Weed control by metabolites produced from Diaporthe schini.

Weed control is a critical factor to ensure productivity and quality for food production. Chemical control is the main method used worldwide, but the demand for healthier food and the farmers' health and environment concerns have led to an increase in the search for alternative control methods. In this way, the use of biomolecules produced by microorganisms that present phytotoxic activity against weeds, such as exopolysaccharides, is attracting attention. For this purpose, this work compared two techniques (solid-state and submerged fermentation) for bioherbicide production by Diaporthe schini. Physicochemical characterization of both fermented broth and evaluation of bioherbicidal effect in post-emergence of Amaranthus viridis, Bidens pilosa, Echinocloa crusgalli, and Lollium multiflorum were performed. Fungal broth obtained by submerged fermentation presented better physicochemical characteristics in terms of viscosity, density, and surface tension. Overall, it was more effective than the broth obtained by solid-state fermentation for weed control because it presented an average inhibition of 40% of weed growth and 45% lower surface tension if compared to the control test. Also, reductions of 1.4-4.2 times of root dry mass, 2.9-5.8 times of shoot dry mass and 1.2-3.9 times of weeds heights, if compared to the control test, were achieved.

Powder containing biomolecules from Diaporthe schini for weed control.

This study describes the use of spray drying technology to obtain a powder containing biomolecules with herbicidal activity produced by submerged fermentation using Diaporthe schini. The efficiency of the bioherbicide was tested for the post-emergence control of Bidens pilosa L., Amaranthus viridis L., Echinochloa crusgalli (L.) Beauv., and Lolium multiflorum Lam. In the first step, different additives were used and lactose was the most suitable one because it resulted in high herbicidal activity and weed suppression. In the second step, process variables were investigated, including inlet air temperature, drying air flow rate, and feed flow rate. The highest herbicidal activity was obtained with an inlet air temperature of 100°C, and air and feed flow rates of 1.4 m3/min and 0.22 L/h, respectively. Maximum herbicidal activities were 38, 45, 21 and 18%, while weed heights reduction were 69.0, 74.3, 20.4 and 24.8% for B. pilosa, A. viridis, E. crusgalli and L. multiflorum, respectively. The bioherbicide was effective to suppress weed growth and spray drying is a promising technology for the production of solid formulations of bioherbicides.

Extraction of bioactive compounds from Senecio brasiliensis using emergent technologies.

Several plant species synthesize biologically active secondary metabolites. Pyrrolizidine alkaloids are a large group of biotoxins produced by thousands of plant species to protect against the attack of insects and herbivores, but they are highly toxic for humans and animals. In this study, extracts from the aerial part of Senecio brasiliensis were obtained using different technologies: ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and microwave hydrodiffusion and gravity (MHG). The study aimed to evaluate the effectiveness of these technologies for the extraction of chemical compounds found in this plant, focusing on two pyrrolizidine alkaloids: integerrimine and senecionine. Influential parameters on yield and chemical composition were also evaluated: for UAE and MHG, temperature and pressure; for PLE, temperature, and percentage of ethanol. All the extraction techniques were efficient for the extraction of integerrimine and senecionine. The UAE and PLE stood out for the higher yields and number of compounds. The PLE presented a maximum yield of 18.63% for the matrix leaf and the UAE a maximum yield of 11.82% for the same matrix. These two techniques also stood out in terms of the number of compounds, once 36 different compounds were found via PLE and 17 via UAE. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02845-1.

Extraction and characterization of polysaccharide-enriched fractions from Phoma dimorpha mycelial biomass.

Ultrasound-assisted extraction (UAE) and pressurized hot water extraction (PHWE) were tested as advanced clean methods to obtain polysaccharides from Phoma dimorpha mycelial biomass. These methods were compared to conventional extraction (hot water extraction, HWE) in terms of polysaccharides-enriched fractions (PEF) yield. A central composite rotational design was performed for each extraction method to investigate the influence of independent variables on the yield and to help the selection of the condition with the highest yield using water as an extraction solvent. The best extraction condition of PEF yielded 12.02 wt% and was achieved when using UAE with direct sonication for 30 min under the intensity of 75.11 W/cm2 and pulse factor of 0.57. In the kinetic profiles, the highest yield (15.28 wt%) was obtained at 50 °C under an ultrasound intensity of 75.11 W/cm2 and a pulse factor of 0.93. Structural analysis of extracted polysaccharide was performed using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermal property. The water solubility index, water holding capacity, and emulsification index of PEF were 31.3 ± 1.5%, 138.1 ± 3.2%, and 62.9 ± 2.3%, respectively. The submerged fermentation demonstrates the huge potential of Phoma dimorpha to produce polysaccharides with bioemulsifying properties as a biotechnologically cleaner alternative if compared to commercial petroleum-derived compounds. Furthermore, UAE and PHWE are green technologies, which can be operated at an industrial scale for PEF extraction.

Different techniques for concentration of extracellular biopolymers with herbicidal activity produced by Phoma sp.

The natural ability of microorganisms to secrete high levels of bioactive compounds make them attractive hosts for producing novel compounds. Microbial biopolymers have potential applications in most of the sectors of the world economy. According to the physicochemical properties, they present some advantages, such as biodegradability, reproducibility, and stability. Based on this context, the objective of this work was to evaluate different methods for concentration and characterisation of extracellular biopolymers produced by Phoma sp. Extracellular biopolymers were produced by submerged fermentation and were concentrated by hollow fibre membranes and by adsorption. The structural characterisation of purified biopolymers was determined by Fourier Transform Infrared spectroscopy. Phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each sample. Hollow-fibre microfiltration membrane presented a higher purification factor than hollow-fibre ultrafiltration membrane. Extracellular biopolymers were identified in the permeate and retentate fractions, but in higher concentration in the retentate fractions. The adsorption process was efficient for recovering more than 88% of extracellular biopolymers from cell-free fermented broth. The best performance was obtained by using silica and activated carbon as adsorbent, with a recovery higher than 93%. The herbicidal activity was proportional to the concentration of biopolymers and the results are very promising for future applications because a concentrated solution of biopolymers can increase weed control. Membrane processes can be used to develop a liquid formulation of bioherbicide, whereas adsorption can be used to develop a solid formula.

An overview of fungal biopolymers: bioemulsifiers and biosurfactants compounds production.

Fungal biopolymers have gained considerable attention from the scientific community for various applications due to their biological and physicochemical properties. The wide applications in several areas, especially in the food industry as a bioemulsifier and in the agricultural area as a biosurfactant, have expanded the knowledge on the production of fungal biopolymers to keep up with developments on this subject area. Recent scientific studies have disclosed novel routes, optimized parameters, increased yields, and other related approaches in order to produce and apply fungal bioemulsifiers and biosurfactants. However, there is a need to gather important information in order to provide a way forward. Therefore, this review presents an overview of properties, applications, and perspectives for encouraging further projects and investments in the near future by most categories of investors. The selection of culture media, the definition of cultivation parameters, extraction, recovery, and purification are the initial steps to indicate the conditions for scale-up. Indeed, scale-up is still one of the challenges in this biotechnological field, which could be solved by expanding the tests and operational productions in both pilot and industrial plants.

Concentration of exopolysaccharides produced by Fusarium fujikuroi and application of bioproduct as an effective bioherbicide.

Exopolysaccharides are secondary metabolites produced by microorganisms and are a subject of research in many fields of science and industry due to some of their confirmed properties, especially in the pharmaceutical and agrochemical areas. In this context, the objectives of this work were to evaluate the potential of Fusarium fujikuroi for producing exopolysaccharides and to concentrate such compounds in order to increase the herbicidal activity. Exopolysaccharides were produced by submerged fermentation and different concentration methods (membranes, lyophilization, and evaporation) were evaluated. The phytotoxic effects were assessed through absorption assays in detached leaves of Cucumis sativus and evaluated on the seventh day after application. The surface tension was evaluated for each concentration method. The production of exopolysaccharides in the crude broth without concentration was 5.94 g/L. When using the lyophilization method, a maximum yield of exopolysaccharides of 10.64 g/L was obtained. The membranes also presented satisfactory results of exopolysaccharides: 9.60 g/L. The increase of bioherbicidal activity and the lower surface tension are proportionally related to the increase of the concentration of exopolysaccharides.

Production of cutinase by solid-state fermentation and its use as adjuvant in bioherbicide formulation.

In the present study, it was presented a strategy to maximize the cutinase production by solid-state fermentation from different microorganisms and substrates. The best results were observed using Fusarium verticillioides, rice bran being the main substrate. Maximum yield of cutinase obtained by the strain was 16.22 U/g. For concentration, ethanol precipitation was used, and the purification factor was 2.4. The optimum temperature and pH for enzyme activity were 35 °C and 6.5, respectively. The enzyme was stable at a wide range of temperature and at all pH values tested. The concentrated cutinase was used as an adjuvant in a formulation containing cutinase + bioherbicide. The use of enzyme increased the efficiency of bioherbicide, since cutinase was responsible to remove/degrade the cutin that recovery the weed leaves and difficult the bioherbicide absorption. Cutinase showed to be a promising product to be used in formulation of bioherbicides.

Concentration of metabolites from Phoma sp. using microfiltration membrane for increasing bioherbicidal activity.

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.

Extracts from Lupinus albescens: antioxidant power and antifungal activity in vitro against phytopathogenic fungi.

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 (CO2) 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 (IC50) 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 CO2 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 CO2 and compressed LPG might be a potential source of antioxidants and natural fungicides.

Importance of Lupinus albescens in agricultural and food-related areas: A review.

The purpose of this review is to assist readers in understanding the importance of Lupinus albescens to nature, farmers, and scientists. L. albescens is mostly found in Argentina, Uruguay, Paraguay, and in "Campanha, Litoral and Missões" regions of State of Rio Grande do Sul (Brazil). Therefore, this review presents information and discussion on this plant that can encourage novel studies in a near future for exploring evermore the biological and physicochemical properties of L. albescens. The plant presents adaptive characteristics of soils with low content of nutrients, being an important plant for the recovering of degraded areas. In the last few years, there was an increase in scientific interest for exploring its chemical composition and biological activities. All plant matrices (i.e., roots, leaves, seeds, and stalks) are rich in antioxidant and antifungal compounds, especially stigmasterol. For example, the extracts obtained from the roots are reported with more than 50 wt% stigmasterol and 25 wt% ergosterol. Furthermore, the extracts present remarkable fungicide effects, especially against Fusarium oxysporum and Fusarium verticillioides.

Production of bioherbicide by Phoma sp. in a stirred-tank bioreactor.

The objective of this work was to produce an herbicide by submerged fermentation in a stirred-tank bioreactor and to assess the potential herbicidal in pre-emergence, post-emergence, and in a detached leaves of Cucumis sativus var species. wisconsin (cucumber) and Sorghum bicolor (sorghum) species. Fermentations were carried out in a stirred-tank bioreactor with useful volume of 3L. Stirring rate (40, 50, and 60 rpm) and aeration (1, 2 and 3 vvm) were the variables studied for bioherbicide production. Fermented broth was fractioned with different solvents to identify the molecules produced by the fungus in a multi-dimensional gas chromatograph system. Bioherbicide showed 100% inhibition of germination of both species in the pre-emergence tests. From detached leaves tests were verified yellowish lesions in Cucumis sativus and necrotic lesions on leaves of Sorghum bicolor. Post-emergence test presented variation of the phytotoxicity from 25 to 66% for the species C. sativus and from 32 to 58% by S. bicolor. The metabolites produced by submerged fermentation of Phoma sp. presented activity in pre-emergence, post-emergence, and detached leaves of C. sativus and S. bicolor and it could be an alternative in the future for weed control.