Review on the background of yeast?centered postharvest biocontrol

Take away- Synthetic fungicides are the most used postharvest?disease management approach- The literature has demonstrated yeasts' commercial?biocontrol potential- Various mechanisms between yeast antagonists and?mold have been discovered- Understanding antagonist yeast?spoilage yeast/bacteria?interactions is crucial- Due to commercialization issues, antifungal cultures are?rarely marketed Fresh fruits and vegetables constitute a large part of the human?diet; they are rich in essential nutrients such as? vitamins, minerals,?dietary fiber, and antioxidants that are important for maintaining?good health (Hossain et al., 2017). The more consumers learn?about the connection between nutrition and health, the more likely?they are to consume fresh fruits and vegetables. According to the?most recent Food and Agriculture Organization (FAO) (2021) data,?58.03 million hectares produced 1.15 billion tons of fresh?vegetables, and 66.48 million hectares produced 909.64 million?tons of fresh fruit, for a total of more than 2 billion tons of fresh?fruit and vegetables produced globally in 2021 (FAO, 2021). Postharvest lossesHowever, after harvesting, fresh fruits and vegetables are subject?to various spoilage processes that can lead to economic losses. The?majority of food deterioration is caused by fungi. Postharvest?losses can account for up to 25% of total fruit and vegetable?production in developed countries but are even greater than 50% in developing countries (Agirman & Erten, 2020; Spadaro &?Droby, 2016).Fungal infections?Fungal infections cause severe deterioration of fruit and?vegetable quality, and the shelf life is greatly shortened. The ratio?of postharvest losses in fruits and vegetables is increasing due to?inadequate transportation, processing, and storage under suboptimal?conditions (Liu et al., 2013). Fungal species belonging to Alternaria,?Aspergillus, Botrytis, Colletotrichum, Fusarium, Geotrichum, Gloeosporium, Monilinia, Mucor, Penicillium, and Rhizopus genera are responsible?for the majority of postharvest diseases (Leyva Salas et al., 2017;?Oufensou et al., 2023). Besides economic issues, infected foods pose?a potential health risk because several fungi, including Alternaria,?Penicillium, and Fusarium, generate mycotoxins, secondary metabolites harmful to human health. For instance, Penicillium expansum is?responsible for the postharvest blue mold that affects a large variety?of fruits such as pear, apple, and peach, and produces a wide range of?mycotoxins, including citrinin, patulin, and chaetoglobosins, all?showing potential to cause cancer (Liu et al., 2013). Green mold,?caused by Penicillium digitatum, is the most common postharvest?disease in citrus. This agent has been recognized as a cause of deadly?pneumonia (Moraes Bazioli et al., 2019; Oshikata et al., 2013). During?their growth phases, Aspergillus (A.) niger, A. carbonarius, and A.?tubingensis are also capable of producing mycotoxins such ochratoxin?A (OTA) and fumonisin B2. Among these mycotoxins, OTA is?reported as the most common toxin in grape and grape?derived?products (wine, grape juice, raisins, etc.) (Pantelides et al., 2015). Postharvest pathogen managementOne of the most important challenges of the fresh fruit and?vegetable sector is effective postharvest pathogen management. The?use of chemical fungicides to manage and control postharvest diseases?is a widespread and effective practice worldwide. Due to their acute,?cumulative, and synergistic effects, the use of chemical fungicides is?strictly regulated by law (de Paiva et al., 2017). According to the?European Food Safety Authority (EFSA), synthetic component residues?were found in about 45% of the food samples analyzed in 2014, with?1.9% of those samples having residues exceeding legal limits; some of?the tested foods were also positive for the presence of pesticides that?are not approved by the European Union (EFSA, 2014). The need of other toolsThe negative?environmental effects of synthetic chemicals, combined with concerns?over the emergence of fungicide?resistant human pathogen biotypes?and a strong consumer desire for food free of pesticide residues,?harmful microorganisms, and toxins, as well as strict legal restrictions on?the use of synthetic fungicides, have led to a global search for safer,?more efficient, low?residue, nontoxic, environmentally and economically?friendly alternative biocontrol methods (Romanazzi et al., 2017; Spadaro?& Droby, 2016). The use of main yeasts, but also molds, lactic acid?bacteria, and Gram?positive and Gram?negative bacteria as microbial?biocontrol agents (BCAs) has emerged as a promising approach among?various methods to prevent postharvest diseases of fruits and?vegetables (Lamont et al., 2017). Biocontrol, antagonists, ...?Biocontrol,? ?biological control,? or ?bio?preservation? refers to?the use of indigenous or added organisms or their metabolites with?antimicrobial effects able to extend the shelf life of foods (Leyva?Salas et al., 2017). Smith (1919) was the first author to use the term ?biological control? to describe the action of natural enemies of alien?insects for the permanent suppression of insect pests (Di Canito?et al., 2021). The goal of a biological control strategy is to limit the?spread or proliferation of an invasive species by using natural?enemies (Kang et al., 2017). In this context, the term ?natural enemy??refers to microorganisms that act as antagonists. The word antagonist?originates from the Greek word ?antagonist?s? (competitor, opponent, enemy, rival) which is derived from anti (against) and?agonizesthai (to contend for a prize). The antagonist microorganism?is the opposite enemy that blocks the main character. Antagonism is?one of the ways microorganisms establish biological balance in?nature. In this relationship, one of the two microorganisms coexisting?directly or indirectly damages the other by impairing its development?and reproduction, and limits or eliminates its survival. StrategiesAccording to?Sharma et al. (2009), there are two main strategies for using microbial?antagonists to reduce postharvest infections of fruits and vegetables.?The first is to use microorganisms that are already present in a?product naturally and that may be encouraged and managed. The?second approach is the artificial introduction of microbial agents?against postharvest pathogens. Aims of the reviewThis review aims to provide information on the background of?yeast?centered postharvest biocontrol procedures by examining the?recent developments in the current literature. The manuscript is?divided into the following sub?sections: (i) the importance of yeasts in?biocontrol applications and the characteristics of an ideal postharvest?antagonist,(ii) microbial interactions within BCAs, (iii) action mechanisms defined in biocontrol systems, (iv) enhancing the bioefficacy of microbial antagonists, (v) commercial applications, and (vi) constraints and future perspectives. More contents2 | IMPORTANCE OF YEASTS IN?BIOCONTROL AND CHARACTERISTICS OF?AN IDEAL POSTHARVEST ANTAGONIST3 | MICROBIAL INTERACTIONS?WITHIN BCAs (biocontrol agents)TABLE 1 Some yeast antagonists are effective in the control of postharvest diseases of fruits and vegetables reported in the literature4 | MECHANISMS OF ACTION OF?MICROBIAL ANTAGONISTS4.1 | Competition for nutrients and space4.2 | Iron depletion4.3 | Parasitism and production of lytic enzymes4.4 | Role of ROS (reactive oxygen species) in the defense response4.5 | Biofilm formation and QS (quorum sensing)4.6 | Secretion of diffusible and volatile?antimicrobial compounds (VOCs, volatile organic compounds)4.7 | Induction of resistance5 | IMPROVING THE BIOEFFICACY OF?MICROBIAL ANTAGONISTS6 | COMMERCIAL APPLICATIONS AND?CHALLENGES7 | FUTURE PROSPECTS AND?SUGGESTIONS TABLE 2 Some commercially available bioprotective products developed to control postharvest diseases in fruits and vegetables?(Agirman et al., 2019; Kowalska et al., 2022; Leyva Salas et al., 2017; Spadaro & Droby, 2016).Ordered by?Manufacturer country, Product trade name & Microorganism, Target pathogens, and Application field? AustriaBlossom ProtectTM.?Aureobasidium pullulansErwinia amylovora, Botrytis cinerea, Colletotrichum gloeosporioidesPome fruits (apples, pears quince) BotectorTM, Aureobasidium?pullulansBotrytis cinerea Apples, pears, strawberries,?grapevines, other fruits CanadaYieldPlusTM, Cryptococcus albidus Botrytis spp.,?Penicillium spp.,?Mucor spp.Pome fruits,?Citrus, pear,?Apple FranceNexyTM. Candida oleophila Botrytis cinerea,?Penicillium expansumPome fruits,?Citrus, banana RomeoTM. Saccharomyces?cerevisiae (cell?walls)Botrytis cinerea,?ErysiphalesLettuce, tomato,?Strawberry, Cucumber and grapevines GermanyBoniProtectTM, Aureobasidium?pullulansBotrytis cinerea,?Penicillium expansum,?Monilinia fructigenaPome fruits South AfricaAvogreenTM, Bacillus subtilus Cercospora spp.,?Colletotrichum spp.Avocado SpainCandifruitTM, Candida sake Penicillium expansum,?Botrytis cinerea,?Rhizopus stoloniferPome fruits PantovitalTM, Pantoea aglomerans Botrytis cinerea,?Penicillium digitatum,?Penicillium expansum,?Rhizopus stolonifer,?Monilinia spp.Citrus,?Pome fruits The NetherlandsShemerTM, Metschnikowia?fructicolaAspergillus niger,?Botrytis cinerea,?Penicillium digitatum,?Penicillium italicum,?Rhizopus stoloniferGrape, carrot,?Strawberry,?Sweet potatoes,?Apricot, peach,?Pepper, citrus NoliTM, Metschnikowia?fructicolaBotrytis cinerea,?Monilinia spp.Soft fruits,?Strawberry,?Stone fruits,?Table/wine grapes? USAAspireTM, Candida oleophila Penicillium expansum,?Botrytis cinerea,?Rhizopus stoloniferCitrus fruits,?Pome fruits,?Apple, peach BioSaveTM, Pseudomonas syringae Penicillium expansum,?Botrytis cinerea,?Mucor piriformis,?Fusarium sambucinum,?Geotrichum candidumPome fruits,?Citrus, pear,?Potatoes,?Cherries,?Apple SerenadeTM, Bacillus subtilusMonilinia fructicola, Erwinia amylovora, Phytophthora infestansGrape, apple, pear, legumes, peanuts AbstractFresh fruits and vegetables are susceptible to a large variety of spoilage agents?before and after harvest. Among these, fungi are mostly responsible for the?microbiological deteriorations that lead to economically significant losses of freshproduce. Today, synthetic fungicides represent the first approach for controlling?postharvest spoilage in fruits and vegetables worldwide. However, the emergence of?fungicide?resistant pathogen biotypes and the increasing awareness of consumers?toward the health implications of hazardous chemicals imposed an urgent need to?reduce the use of synthetic fungicides in the food supply; this phenomenon?strengthened the search for alternative biocontrol strategies that are more effective,?safer, nontoxic, low?residue, environment friendly, and cost?effective. In the last?decade, biocontrol with antagonistic yeasts became a promising strategy to reduce?chemical compounds during fruit and vegetable postharvest, and several yeast?based biocontrol products have been commercialized. Biocontrol is a multipartite?system that includes different microbial groups (spoilage mold, yeast, bacteria, andnonspoilage resident microorganisms), host fruit, vegetables, or plants, and the?environment. The majority of biocontrol studies focused on yeast?mold mechanisms,?with little consideration for yeast?bacteria and yeast?yeast interactions. The current?review focused mainly on the unexplored yeast?based interactions and the?mechanisms of actions in biocontrol systems as well as on the importance and?advantages of using yeasts as biocontrol agents, improving antagonist efficiency, the?commercialization process and associated challenges, and future perspectives. SourcesExploring yeast?based microbial interactions: The next?frontier in postharvest biocontrolBilal Agirman, Erdem Carsanba, Luca Settanni & Huseyin ErtenYeast, Wiley, 2023DOI: 10.1002/yea.3895https://onlinelibrary.wiley.com/doi/pdf/10.1002/yea.3895 Picture, IRTA, New biological control strategy for rot control in grapes, https://www.irta.cat/es/nueva-estrategia-de-control-biologico-de-la-podredumbre-de-la-uva/