Evaluating a preventive biological control agent applied on grapevines against Botrytis cinerea and its influence on winemaking

Biocontrol strategies against Botrytis cinerea in viticulture: evaluating the efficacy and mode of action of selected winemaking yeast strains

Botrytis cinerea poses a recurring threat to viticulture, causing significant yield losses each year. The study explored the biocontrol capabilities of commercially used winemaking yeasts as a strategy to manage B. cinerea in grape berries. The winemaking yeast strains-Saccharomyces cerevisiae ES181, Saccharomyces pastorianus KBG6, S. cerevisiae BCS103, Lachancea thermotolerans Omega, and Torulaspora delbrueckii TD291-reduced B. cinerea growth and conidiation in vitro. Furthermore, they demonstrated a decreased disease severity and number of conidia in grape berries. Among these strains, S. cerevisiae BCS103 was the most effective, inducing the expression of the defense-related gene PR4 in berries. Its diffusible compounds and volatile organic compounds also reduced the expression of BcLTF2, a positive regulator of B. cinerea conidiogenesis. The examined winemaking yeast strains, especially S. cerevisiae BCS103, demonstrated effective inhibition of B. cinerea in vitro and in grape berries, influencing key defense genes and reducing BcLTF2 expression, offering potential solutions for disease management in viticulture. The study underscores the promise of commercially available winemaking yeast strains as eco-friendly tools against B. cinerea in viticulture. Leveraging their safety and existing use in winemaking offers a potential avenue for sustainable disease management.

Molecular Identification of Juglans Regia Endophyte LTL-G3, Its Antifungal Potential and Bioactive Substances

Background

Endophyte is one of the potential biocontrol agents for inhibiting plant pathogens. However, the mechanisms and characteristics involved in the inhibition of different phytopathogenic fungi by endophytes, especially walnut endophytes, are still largely unknown.

Objectives

The present study aimed to identify the walnut endophytic fungus LTL-G3 from a genetic point of view, assess the strain's antifungal activity, and determine the bioactivities of the substances it produces against plant pathogens.

Materials and Methods

The homologous sequence of strain LTL-G3 was examined, and typical strains of the Trichoderma virens group were used to build NJ phylogenetic trees and analyze the taxonomic position of the strain. The biocontrol agent's antagonistic potential for many plant pathogenic fungi. By using silica gel G chromatography, the active components of the strain were separated and purified. The active components were identified using GC-MS and NMR.

Results

The strain LTL-G3 was identified as Trichoderma virens. Its fermentation and secondary metabolite extracts had a broad spectrum and strong inhibitory effect on the spread of six plant pathogens (Botrytis cinerea, Fusarium graminearum, Gloeosporium fructigenum, Phytophthora capsici, Rhizoctonia solani, and Valsa mali) evaluated, of which, its inhibition rate against Valsa mali reached 76.6% (fermentation extract) and 100% (ethyl acetate and n-butanol extracts). On silica gel G chromatography, bioactive compounds were divided into 6 fractions and 7 sub-fractions. Fr.2-2 was the sub-fraction that showed the greatest inhibitory against V. mali, as an inhibition percentage of 89.36% in 1 mg. mL-1. Fifteen key inhibitory chemicals identified using GC-MS. By examining the NMR data, the chemical make-up of the precipitated white solid was identified. The inhibition rate against V. mali increased by over 95% at a dosage of 1 mg. mL-1, indicating a significant linear association between compound A and that rate.

Conclusions

The strain LTL-G3 can be applied as an efficient biological control agent against V. mali, and its highly inhibitive secondary metabolites provide the mechanism for this action.

In Vitro Evaluation of Some Endophytic Bacillus to Potentially Inhibit Grape and Grapevine Fungal Pathogens

Romania has a long history of grapevine culturing and winemaking. However, like any agricultural sector, viticulture faces devastating biological threats. Fungi responsible for grapevine trunk diseases (GTDs) and grape spoilage lead to considerable yield losses and a decline in grapevine quality. In the actual context, many countries, including Romania, have reoriented their approaches to minimize chemical inputs, which have been proven to be toxic and to have negative impacts on the environment, and to replace them with sustainable biocontrol strategies for the wine-growing sector. Within biocontrol strategies, Bacillus spp. is a well-known plant-protective bacteria with antifungal properties. Within this paper, six endophytic bacteria from various plant sources were studied. The bacterial strains were identified as B. pumilus, B. subtilis, and B. velezensis by sequencing their 16S rDNA region. Regardless of the in vitro test methods (using living bacterial cells, bacterial-cell-free supernatant (CFS), and volatile active compounds (VOCs)), B. velezensis strains revealed strong and broad antifungal activity against grape and grapevine fungal pathogens such as Aspergillus spp., Botrytis cinerea, Penicillium expansum, Diplodia seriata, Eutypa lata, Fusarium spp., Clonostachys rosea, Neofusicoccum parvum, and Stereum hirsutum. The functional antifungal genes encoding for difficidin, fengycin, iturins, macrolactin, and mycosubtilin were molecularly detected, which could support the proven antifungal activity of the endophytic strains. Lytic enzymes involved in fungal growth inhibition, such as chitinase, cellulase, and proteases, were also revealed to be produced by some of these bacterial strains. Various other in vitro tests, such as phosphate and phytate solubilization, phytohormone synthesis, the production of enzymes involved in the polyamine biosynthetic pathway, and pH as well as temperature tolerance tests were carried out to reveal the plant-beneficial potential of these bacterial strains. These results revealed that the B. velezensis strains, especially BAHs1, are the most suitable endophytes for grapevine biologic control, which could lead to the future development of sustainable management strategies.

Improved procedure for square-wave voltammetric sensing of fenhexamid residues on blueberries peel surface at the anodically pretreated boron-doped diamond electrode

BACKGROUND

Fungicide fenhexamid (FH) has a high residual concentration on fruits and vegetables, thus, it is of high importance to monitor the level of FH residues on foodstuff samples. So far, the assay of FH residues in selected foodstuff samples has been conducted by electroanalytical methods on sp² carbon-based electrodes that are well-known to be susceptible to severe fouling of the electrodes surfaces during electrochemical measurements. As an alternative, sp³ carbon-based electrode such as boron-doped diamond (BDD) can be used in the analysis of FH residues retained on the peel surface of foodstuff (blueberries) sample.

RESULTS

In situ anodic pretreatment of the BDDE surface was found to be the most successful strategy to remediate the passivated BDDE surface by FH oxidation (by)products, and the best validation parameters, i.e., the widest linear range (3.0-100.0 μmol L^-1), the highest sensitivity (0.0265 μA L μmol^-1) and the lowest limit of detection (0.821 μmol L^-1), were achieved on the anodically pretreated BDDE (APT-BDDE) in a Britton-Robinson buffer, pH 2.0, using square-wave voltammetry (SWV). The assay of FH residues retained on blueberries peel surface was performed on the APT-BDDE using SWV, and the obtained concentration of FH residues of 6.152 μmol L^-1 (1.859 mg kg^-1) was found to be below the maximum residue value fixed for blueberries by the European Union regulations (20 mg kg^-1).

SIGNIFICANCE AND NOVELTY

In this work, a protocol based on a very easy and fast foodstuff sample preparation procedure combined with the straightforward pretreatment approach of the BDDE surface was elaborated for the first time for the monitoring of the level of FH residues retained on the peel surface of blueberries samples. The presented reliable, cost-effective, and easy-to-use protocol could find its application as a rapid screening method for the control of food safety.

Agroecological Management of the Grey Mould Fungus Botrytis cinerea by Plant Growth-Promoting Bacteria

Botrytis cinerea is the causal agent of grey mould and one of the most important plant pathogens in the world because of the damage it causes to fruits and vegetables. Although the application of botrycides is one of the most common plant protection strategies used in the world, the application of plant-beneficial bacteria might replace botrycides facilitating agroecological production practices. Based on this, we reviewed the different stages of B. cinerea infection in plants and the biocontrol mechanisms exerted by plant-beneficial bacteria, including the well-known plant growth-promoting bacteria (PGPB). Some PGPB mechanisms to control grey mould disease include antibiosis, space occupation, nutrient uptake, ethylene modulation, and the induction of plant defence mechanisms. In addition, recent studies on the action of anti-Botrytis compounds produced by PGPB and how they damage the conidial and mycelial structures of the pathogen are reviewed. Likewise, the advantages of individual inoculations of PGPB versus those that require the joint action of antagonist agents (microbial consortia) are discussed. Finally, it should be emphasised that PGPB are an excellent option to prevent grey mould in different crops and their use should be expanded for environmentally friendly agricultural practices.

Stereoselective behavior and residues of the imazalil during strawberry growth and strawberry wine production

Imazalil is a chiral fungicide widely used to protect strawberries against gray mold, which may pose threats to food safety. This study aims to investigate the stereoselective behavior of imazalil during strawberry growth and strawberry wine production. A method was proposed and validated for the extraction and quantitative analysis of imazalil residues in strawberry, strawberry pomace, and strawberry wine by using ultra-high performance liquid chromatography-tandem mass spectrometry. The method exhibited mean recoveries ranging from 86.2% to 119.7% with relative standard deviations of 0.1-11.3%. The dissipation curve of imazalil during strawberry growth followed the first-order kinetic model with a half-life ranging from 6.5 to 7.1 days. Significant enantioselectivity of imazalil was observed in strawberry grown under field conditions and strawberry wine production process, with enantiomeric fraction values ranging from 0.51 (2 h) to 0.42 (27d) and from 0.48 (0d) to 0.52 (10d), respectively. (+)-imazalil was preferentially degraded in strawberry under field conditions, while (-)-imazalil was preferentially degraded during the fermentation process. The processing factor was lower than 1 for each procedure, indicating that the wine-making process can reduce imazalil residue in strawberry. These findings may facilitate a more accurate risk assessment of imazalil and provide important guidance for the safe and efficacious use of imazalil in agriculture.

Monitoring the behavior of imazalil and its metabolite in grapes, apples, and the processing of fruit wine at enantiomeric level

BACKGROUND

Imazalil is widely used in agriculture, which may pose a threat to food safety. This study aimed to investigate the fate of imazalil and its main metabolite, R14821 (imazalil-M), in field grapes and apples, and in the processing of fruit wine at the enantiomeric level.

RESULTS

Analysis method was established to determine imazalil and imazalil-M enantiomers in grape, apple, fruit wine and pomace. The method showed acceptable recoveries of 71.6-99.9% and precision with relative standard deviation of 0.3-11.7%. Processing factors (PFs) were 0.15-0.40 (for imazalil enantiomers) and <0.13-0.83 (for imazalil-M enantiomers) during the wine-making process. The PFs after individual steps including washing, peeling, fermentation, and clarification were all less than 1. No enantioselective dissipation of imazalil was found in grapes under field conditions with half-lives of 23.82-24.49 days. R-(-)-imazalil degraded slightly faster than S-(+)-imazalil in apples under field conditions with half-lives of 9.82-10.09 days. S-(+)-imazalil-M preferentially degraded in field grapes and apple. No significant enantioselectivity of imazalil and imazalil-M was observed during the wine-making process. The enantiomeric fraction (EF) values of imazalil were 0.484-0.511 and 0.509-0.522 in grape wine and cider, respectively. The EFs were 0.484-0.501(in grape wine) and 0.484-0.504 (in cider) for imazalil-M.

CONCLUSION

The results showed that the wine-making process could reduce imazalil and imazalil-M residues in grapes and apples. The finding of non-enantioselectivity of imazalil during the processing of fruit wine was useful for accurate risk assessment for imazalil in raw and processing fruits. © 2021 Society of Chemical Industry.

Occurrence and impact of fungicides residues on fermentation during wine production- A review

Continuous fungicide spraying is required to eliminate fungal pathogens on grapes. However, this practice is associated with several risks, including contamination and environmental imbalance, as well as toxicity to operators and the induction of resistance in pathogens. In addition, a strong correlation has been reported between the presence of fungicides and the occurrence of issues during alcoholic fermentation, resulting in negative impacts on the sensory quality of the final products. Numerous studies have evaluated residue concentrations of phytosanitary products in grapes, juices, and wines, and a significant number of studies have assessed the impact of different agrochemicals on bioprocesses. However, a review compiling the key results of these studies is currently lacking. This review incorporates results obtained in the last decade from research on the presence of fungicide residues, including azoxystrobin, boscalid, captan, copper, fenhexamid, folpet, pyraclostrobin, pyrimethanil and tebuconazole, and their effects on fermentation kinetics. Practical solutions to mitigate these problems, both in vineyards and industry, are also presented and discussed. This review highlights the constant high fungicidal agent concentrations (greater than 1 or 2 mg L^-1) used throughout the winemaking process, with the impact of residues being of particular concern, especially with regard to their effect on yeast activity and the fermentation process. Thus, the adoption of methodologies that allow winemakers to control and trace these residues is an important step in avoiding or reducing fermentation problems throughout the winemaking process.[Figure: see text].

Enriched cereal bars with wine fermentation biomass

BACKGROUND

Cereal bars are a sweet-tasting, nutritious, and enjoyable source of vitamins, minerals, and fiber. Ingredients can be added to the formulation to improve certain characteristics, such as protein content. Some of these ingredients are derived from yeast from fermentation processes. This study aimed to add value to the residue resulting from the wine fermentation process (wine lees) by applying it in the formulation of cereal bars.

RESULTS

Three formulations of cereal bars with different concentrations of autolyzed yeast biomass were developed. The effect of the addition of biomass was investigated by chemical and sensorial analysis. The cereal bar with the highest concentration of autolyzed biomass (5%) showed the highest protein content (73.4 g kg^-1 ). The findings regarding acceptance obtained by sensory analysis showed that the samples with 2.5% and 5% autolyzed biomass pleased consumers.

CONCLUSIONS

Formulations of autolyzed biomass-based cereal bars have increased protein content as the autolyzed biomass concentration has increased. Moreover, the acceptance of the cereal bars with autolyzed biomass in concentrations of 2.5% and 5% was satisfactory. The use of wine lees in food products is therefore a possible way of adding value to this residue, including, for example, a significant increase in protein. © 2020 Society of Chemical Industry.

Microbial-based Biocontrol Solutions for Fruits and Vegetables: Recent Insight, Patents, and Innovative Trends

BACKGROUND

Fruits and vegetables are susceptible to colonisation by undesired microflora, which, in pre- and post-harvest conditions, negatively impact the quality of these products, leading to a reduction of yield, shelf-life, and marketability. In the few last years, the use of microbial Biological Control Agents (BCAs) has assumed international relevance in order to control harmful microorganisms, as a promising alternative to chemical interventions.

OBJECTIVE

The purpose of this review is to discuss the microbial-based solutions applicable for the biocontrol of the main microbial spoilers, phytopathogens, and human food-borne pathogens affecting fruits and vegetables during their production and storage.

RESULTS

A comprehensive overview of the scientific literature investigating the effectiveness of BCA-based products available on the market is provided, as well as of the most recent patents protecting biotechnological applications in this field. Innovative trends are discussed, with a particular focus on the integration of BCAs to minimise spoilage phenomena and microbiological risks adopting combined approaches.

CONCLUSION

This study underlines the growing interest about biocontrol strategies to counteract the growth of spoilage and/or pathogenic microorganisms indicating that in the next years a considerable increase of commercial products and patents will be developed worldwide to exploit innovative biotechnological solutions in the sector.

Unraveling the environmental impacts of bioactive compounds and organic amendment from grape marc

In a society that produces large amounts of solid waste, the search for new methods of valorisation has led to the development of techniques that make it possible to obtain new products from waste. In the case of bio-waste, biological treatment such as anaerobic digestion or composting appear to be suitable options for producing bio-energy or bio-fertilizers respectively. Vermicomposting is a method of converting solid organic waste into resources through bio-oxidation and stabilization of the organic waste by earthworms. The purpose of this study is to establish the environmental impacts of a complete route for the valorisation of grape pomace in order to identify environmental hotspots. In this valorisation route, different value-added products are produced with potential application in the cosmetic, food and pharmaceutical sectors. Priority was given to the use of primary data in the elaboration of the data inventories needed to perform the life cycle assessment (LCA). The main findings from this study reported that the energy requirement of the distillation process is an important hot spot of the process. Although the valorisation route has some poor results in terms of the two environmental indicators (carbon footprint and normalised impact index), when economic revenues were included in this analysis, its environmental performance was better than that of other alternatives for bio-waste recovery.

Environmental assessment of viticulture waste valorisation through composting as a biofertilisation strategy for cereal and fruit crops

Composting is a solid waste management alternative that avoids the emission of methane associated with its disposal in landfill and reduces or eliminates the need for chemical fertilisers if compost is applied. The main objective of this study was to analyse the environmental burdens of composting as a way to achieve a more circular valorisation of wine waste. To do so, with the purpose of identifying optimal operational conditions and determining the "hotspots" of the process, the life cycle assessment (LCA) methodology was used. The consumption of diesel fuel in machinery was determined to be the main critical point in the environmental effects of the system, followed by the transport and distribution of the compost. After the application of compost instead of mineral fertilisers, corn, tomato and strawberry crops would have a better environmental performance in most impact categories. In this sense, a maximum improvement of 65% in terrestrial ecotoxicity is achieved in strawberry cultivation. In light of the results obtained, it is demonstrated that composting is a suitable way of organic waste valorisation according to Circular Economy principles.

Biocontrol of Botrytis cinerea on Grape Berries as Influenced by Temperature and Humidity

Six commercial biocontrol agents (BCAs, containing Aureobasidium pullulans, Bacillus amyloliquefaciens, Bacillus amyloliquefaciens plantarum, Bacillus subtilis, Pythium oligandrum, or Trichoderma atroviride) were applied to ripening berries that were then incubated at one of four temperatures (T, 15, 20, 25, and 30°C) and one of four relative humidity levels (RH, 60, 80, 90, and 100%). After 1 to 13 days of incubation (BCA colonization period), the berries were inoculated with conidia of Botrytis cinerea and kept at 25°C and 100% RH for 7 days, at which time Botrytis bunch rot (BBR) was assessed. The response of BBR control to T/RH conditions and BCA colonization period differed among BCAs; the coefficients of variation among the BCAs ranged from 44.7 to 72.4%. An equation was developed that accounted for the combined effects of T, RH, and BCA colonization period on BBR control. The equation, which had an R²>0.94, could help farmers select the BCA to be used for a specific application based on weather conditions at the time of treatment and in the following days.

Integrated evaluation of wine lees valorization to produce value-added products

The integrated evaluation of the valorization of wine lees to produce value-added products was carried out in this study from a life-cycle perspective. The consumption of steam has been demonstrated as the main hot spot, reaching 85.7% of the impact on Fossil Depletion and 85.3% on Climate Change. Bearing in mind that four different value-added products are produced, a sensitivity analysis was carried out in order to ascertain the influence of the functional unit and the allocation method on the environmental outcomes. The performance of this system was compared to other processes that produce antioxidants from different raw materials. These processes were phycocyanin recovery from Spirulina platensis cyanobacterium, the production of the red antioxidant astaxanthin by microalgae and the valorization of the macroalgae Sargassum muticum. Wine lees valorization showed a better environmental profile throughout the entire life cycle, due to the fact that most of the operations performed are physical (solid/liquid separations, distillations, evaporations, etc.) and do not involve a large consumption of electricity or chemicals. However, there is still room for improvement, and future research should focus on optimizing the extraction of antioxidants from wine lees using two-stages aqueous systems, ultrasonic or microwave assisted extraction, in the pursuit of better performance and lower environmental impact.

Biocontrol activity of Starmerella bacillaris yeast against blue mold disease on apple fruit and its effect on cider fermentation

The reduction of chemical fungicides in agriculture has led to the use of microorganisms as biocontrol agents. Starmerella bacillaris is a non-Saccharomyces yeast associated with overripe and botrytized grape berries microbiota. Its use has been proposed for wine fermentation because of yeast fructophilic character and high glycerol production. Recently, S. bacillaris has been demonstrated to possess antifungal activity against Botrytis cinerea on the grape. Penicillium expansum is the pathogen responsible for the blue mold rot, the most important postharvest disease of apples. These fruits are the raw material of the cider, an alcoholic beverage commonly produced using S. cerevisiae starter cultures. In this study 14 S. bacillaris strains have been studied to evaluate their postharvest antifungal activity against P. expansum on apples. Moreover, the fermentation performances in apple juice of these non-Saccharomyces strains were tested, both in single-strain fermentation and in sequential fermentation, together with S. cerevisiae. Four S. bacillaris strains, able to significantly decrease blue mold rot symptoms and to increase glycerol content during fermentation have been selected to improve apple and cider quality.