Impact of Chemical and Biological Fungicides Applied to Grapevine on Grape Biofilm, Must, and Wine Microbial Diversity

Recent advances in biocontrol and other alternative strategies for the management of postharvest decay in table grapes

During postharvest, table grapes are often spoiled by molds. Aspergillus sp., Alternaria sp., Botrytis sp., Cladosporium sp. and Penicillium sp. are different mold genera frequently related to table grape rot. Fungal spoilage affects nutritional value and organoleptic properties while also producing health hazards, such as mycotoxins. Traditionally, synthetic fungicides have been employed to control fungal diseases. However, possible negative effects on health and the environment are a serious concern for consumers and government entities. This review summarized data on innovative strategies proposed to diminish postharvest losses and extend table grape shelf life. Among physical, chemical, and biological strategies, either alone or in combination, the integrated management of fungal diseases is a sustainable alternative to synthetic fungicides. However, to date, only a few alternative technologies have succeeded on a commercial scale. Recent research aimed at increasing the competitiveness of alternative technologies has led to the development of integrated management strategies to prevent postharvest decay and increase the safety and quality of table grapes.

Yeasts Inoculation Effect on Bacterial Development in Carbonic Maceration Wines Elaboration

Carbonic maceration (CM) vinification is a very traditional method that allows saving energy without great equipment investment, obtaining high-quality wines. However, due to its particularities, CM winemaking implies a higher risk of microbial alteration. This work studies the evolution of bacterial population along carbonic maceration wines elaboration with and without yeast inoculation. In the same way, two strategies of yeast inoculation were studied: "pied de cuve" and Active Dry Yeasts (ADY) seed. For this purpose, three conditions were assayed: spontaneous fermentation (without inoculation), "pied de cuve" technology, and ADY inoculation. For each condition, two winemaking methods were compared: carbonic maceration and the standard method of destemming and crushing (DC). The bacterial evolution (lactic acid and acetic acid bacteria) was followed in different fermentation stages. Finally, the wines obtained were analysed (pH and volatile acidity). In the non-inoculated wines produced by CM, high development of the bacterial population was observed (counts of acetic acid bacteria around 4.3 log cfu/mL), and finished wines presented high values of volatile acidity (>1.5 g/L), which did not occur in the inoculated vinifications (counts of acetic acid bacteria around 1.5 log cfu/mL and 0.5 g/l of volatile acidity). Thus, the control of yeast population, as a "pied de cuve" as ADY seed, seems to be an effective tool to avoid bacterial alterations in CM vinifications.

Mechanism of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) in controlling microbial problems in aircraft fuel systems

This research investigated the potential use of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) as a biocide in aircraft fuel systems, which is rarely studied due to the unique properties of such systems. The study assessed the effectiveness of CMIT against three microbial isolates using minimum inhibitory concentrations and bacteriostatic tests, and showed that CMIT had good activity against them. Electrochemical studies were conducted to determine the impact of CMIT on the 7B04 aluminum alloy, which demonstrated that CMIT acted as a cathodic inhibitor and exhibited certain levels of short-term and long-term corrosion inhibition effects at concentrations of 100 mg L^-1 and 60 mg L^-1, respectively. Additionally, the research provided insights into the mechanisms governing microbial problems by studying the reaction of CMIT with glutathione and sulfate. Overall, the study suggested that CMIT may be a useful biocide in aircraft fuel systems and provided important information on its efficacy and mechanism of action.

Bioprotective Effect of a Torulaspora delbrueckii/Lachancea thermotolerans-Mixed Inoculum in Red Winemaking

One of the alternatives to SO2 as an antimicrobial is the use of bioprotection yeasts, which colonize the medium preventing the proliferation of undesirable microorganisms. In this work, the bioprotective effect of a mixed inoculum formed by Torulaspora delbrueckii/Lachancea thermotolerans during fermentation was evaluated. For this purpose, fermentations were carried out using this mixed inoculum and the populations of yeasts, lactic bacteria and acetic bacteria, and the physical–chemical parameters of the wines obtained were studied. The results were compared with those obtained in spontaneous fermentation with and without SO2. The different fermentation strategies caused a differentiation in the yeast species present during fermentation. Regarding populations of lactic acid bacteria, results showed that the effect of the addition of the mixed inoculum was comparable to that exerted by SO2. On the other hand, due to the high sensitivity of acetic acid bacteria to SO2, the sulfite vinifications showed a lower population of acetic acid bacteria in the early stages of fermentation, followed by the vinifications with the mixed inoculum.

A fundamental landscape of fungal biogeographical patterns across the main Chinese wine-producing regions and the dominating shaping factors

The microbial terroir plays an indispensable role in the formation of regional wine characteristics. A fundamental landscape of the fungal biogeographical patterns across Chinese wine-producing regions was obtained by characterizing the fungal communities in spontaneous fermentation. After confirming the established national microbial terroir, the fungal heterogeneity was evaluated at different geographical levels. The result showed that the variation between the wineries was more evident than at a regional level. Moreover, the microbial comparability from various regions with similar climates or wineries within the same regions was revealed. Further discriminant analysis determined the specific fungal biomarkers in different regions, while the associated reverse identification model displayed reliable accuracy (>70%). Correlation analysis illustrated the primary role of the geoclimatic factors (>41%) in shaping the fungal geographical patterns, and the relationship between the microbiome and spontaneous fermentation performance. In addition to expanding the knowledge regarding wine microbes, these findings provided a new benchmark for harnessing the microbial terroir to enhance regional wine expression.

COLMENA: A Culture Collection of Native Microorganisms for Harnessing the Agro-Biotechnological Potential in Soils and Contributing to Food Security

COLMENA is a microbial culture collection dedicated to the characterization, classification, preservation, and transferal of native microorganisms isolated from various agro-systems and other ecosystems in Mexico. This collection aims to protect microbial diversity, reducing soil degradation, but also exploiting its agro-biotechnological potential. So far, COLMENA has isolated and cryopreserved soil microorganisms from different crops in two major agricultural regions in Mexico, the Yaqui Valley, Sonora, and the Fuerte Valley, Sinaloa. COLMENA has specialized in the identification and characterization of microbial strains with metabolic capacities related to the promotion of plant growth and the biocontrol of phytopathogens. Thus, COLMENA has identified several promising plant growth-promoting microbial (PGPM) strains due to their metabolic and genetic potentials and their beneficial effects in vivo and field trials. These findings demonstrate the biotechnological potential of these strains for their future use in profitable agricultural alternatives focused on enhancing global food security. To share the knowledge and results of the COLMENA team’s scientific research, a virtual platform was created, where the database of the studied and preserved microorganisms is available to professionals, researchers, agricultural workers, and anyone who is interested.

Increased Organic Fertilizer and Reduced Chemical Fertilizer Increased Fungal Diversity and the Abundance of Beneficial Fungi on the Grape Berry Surface in Arid Areas

Fertilizer practices can significantly impact the fruit quality and microbial diversity of the orchards. The fungi on the surface of fruits are essential for fruit storability and safety. However, it is not clear whether fertilization affects the fungal diversity and community structure on the surface of grape berries. Here, grape quality and the fungal diversity on the surface of grapes harvested from three fertilizer treatments were analyzed shortly after grape picking (T0) and following 8 days of storage (T1). The study involved three treatments: (1) common chemical fertilizer for 2 years (CH); (2) increased organic fertilizer and reduced chemical fertilizer for 1 year (A.O); and (3) increased organic fertilizer and reduced chemical fertilizer for 2 years (B.O). The application of increased organic fertilizer and reduced chemical fertilizer increased the soluble solids content (SSC) of the grape berries and decreased the pH of the grape juice. A total of 827,947 high-quality fungal sequences were recovered and assigned to 527 operational taxonomic units. Members of the Ascomycota phylum were dominant in all samples and accounted for 94.41% of the total number of detected sequences, followed by the Basidiomycota (5.05%), and unidentified fungi (0.54%). Alpha and beta diversity analyses revealed significantly different fungal populations in the three fertilizer treatments over the two time periods. The fungal diversity and richness on the grape berry surface in the B.O and A.O treatments were higher than those in the CH treatment. Among the detected fungi, the B.O treatments were mainly Pichia, Aureobasidium, and Candida genera, while the CH treatments were Botrytis, Aspergillus, and Penicillium. Moreover, significant differences were revealed between the two assessment times (T0 and T1). The samples from the T0 timepoint had higher fungal richness and diversity than the samples from T1 timepoint. Increasing organic fertilizer usage in grape management could improve grape quality and went on to increase the fungal diversity, as well as the relative abundance (RA) of beneficial fungi on grape berry surfaces. The correlation analysis suggested that the pH of the grape juice was significantly negatively correlated with fungal diversity parameters.

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].

Screening of Marine Bioactive Antimicrobial Compounds for Plant Pathogens

Plant diseases have been threatening food production. Controlling plant pathogens has become an important strategy to ensure food security. Although chemical control is an effective disease control strategy, its application is limited by many problems, such as environmental impact and pathogen resistance. In order to overcome these problems, it is necessary to develop more chemical reagents with new functional mechanisms. Due to their special living environment, marine organisms have produced a variety of bioactive compounds with novel structures, which have the potential to develop new fungicides. In the past two decades, screening marine bioactive compounds to inhibit plant pathogens has been a hot topic. In this review, we summarize the screening methods of marine active substances from plant pathogens, the identification of marine active substances from different sources, and the structure and antibacterial mechanism of marine active natural products. Finally, the application prospect of marine bioactive substances in plant disease control was prospected.

Genome Assembly and Transcriptome Analysis of the Fungus Coniella diplodiella During Infection on Grapevine (Vitis vinifera L.)

Grape white rot caused by Coniella diplodiella (Speg.) affects the production and quality of grapevine in China and other grapevine-growing countries. Despite the importance of C. diplodiella as a serious disease-causing agent in grape, the genome information and molecular mechanisms underlying its pathogenicity are poorly understood. To bridge this gap, 40.93 Mbp of C. diplodiella strain WR01 was de novo assembled. A total of 9,403 putative protein-coding genes were predicted. Among these, 608 and 248 genes are potentially secreted proteins and candidate effector proteins (CEPs), respectively. Additionally, the transcriptome of C. diplodiella was analyzed after feeding with crude grapevine leaf homogenates, which reveals the transcriptional expression of 9,115 genes. Gene ontology enrichment analysis indicated that the highly enriched genes are related with carbohydrate metabolism and secondary metabolite synthesis. Forty-three putative effectors were cloned from C. diplodiella, and applied for further functional analysis. Among them, one protein exhibited strong effect in the suppression of BCL2-associated X (BAX)-induced hypersensitive response after transiently expressed in Nicotiana benthamiana leaves. This work facilitates valuable genetic basis for understanding the molecular mechanism underlying C. diplodiella-grapevine interaction.

Unusual Non-Saccharomyces Yeasts Isolated from Unripened Grapes without Antifungal Treatments

There a lot of studies including the use of non-Saccharomyces yeasts in the process of wine fermentation. The attention is focused on the first steps of fermentation. However, the processes and changes that the non-Saccharomyces yeast populations may have suffered during the different stages of grape berry ripening, caused by several environmental factors, including antifungal treatments, have not been considered in depth. In our study, we have monitored the population dynamics of non-Saccharomyces yeasts during the ripening process, both with biochemical identification systems (API 20C AUX and API ID 32C), molecular techniques (RFLP-PCR) and enzymatic analyses. Some unusual non-Saccharomyces yeasts have been identified (Metschnikowia pulcherrima, Aureobasidium pullulans, Cryptococcus sp. and Rhodotorula mucilaginosa). These yeasts could be affected by antifungal treatments used in wineries, and this fact could explain the novelty involved in their isolation and identification. These yeasts can be a novel source for novel biotechnological uses to be explored in future work.

From the Vineyard to the Winery: How Microbial Ecology Drives Regional Distinctiveness of Wine

Wine production is a complex process from the vineyard to the winery. On this journey, microbes play a decisive role. From the environment where the vines grow, encompassing soil, topography, weather and climate through to management practices in vineyards, the microbes present can potentially change the composition of wine. Introduction of grapes into the winery and the start of winemaking processes modify microbial communities further. Recent advances in next-generation sequencing (NGS) technology have progressed our understanding of microbial communities associated with grapes and fermentations. We now have a finer appreciation of microbial diversity across wine producing regions to begin to understand how diversity can contribute to wine quality and style characteristics. In this review, we highlight literature surrounding wine-related microorganisms and how these affect factors interact with and shape microbial communities and contribute to wine quality. By discussing the geography, climate and soil of environments and viticulture and winemaking practices, we claim microbial biogeography as a new perspective to impact wine quality and regionality. Depending on geospatial scales, habitats, and taxa, the microbial community respond to local conditions. We discuss the effect of a changing climate on local conditions and how this may alter microbial diversity and thus wine style. With increasing understanding of microbial diversity and their effects on wine fermentation, wine production can be optimised with enhancing the expression of regional characteristics by understanding and managing the microbes present.

The Influence of Fungicide Treatments on Mycobiota of Grapes and Its Evolution during Fermentation Evaluated by Metagenomic and Culture-Dependent Methods

The present study evaluated the impact of organic and conventional fungicide treatments compared with untreated samples (no fungicides were used) on the grape berry yeast community of the Montepulciano variety. The yeast dynamics during the spontaneous fermentation using culture-dependent and -independent methods was also evaluated. Results showed a reduction of yeast biodiversity by conventional treatments determining a negative influence on fermenting yeasts in favor of oxidative yeasts such as Aerobasidium pullulans. Starmerella bacillaris was significantly more present in organic samples (detected by next generation sequencing (NGS)), while Hanseniaspopa uvarum was significantly less present in untreated samples (detected by the culture-dependent method). The fermenting yeasts, developed during the spontaneous fermentation, were differently present depending on the fungicide treatments used. Culture-dependent and -independent methods exhibited the same most abundant yeast species during the spontaneous fermentation but a different relative abundance. Differently, the NGS method was able to detect a greater biodiversity (lower abundant species) in comparison with the culture-dependent method. In this regard, the methodologies used gave a different picture of yeast dynamics during the fermentation process. The results indicated that the fungal treatments can influence the yeast community of grapes leading must fermentation and the final composition of wine.