Exploitation of microbial antagonists for the control of postharvest diseases of fruits: a review

Abstract

Fungal diseases result in significant losses of fruits and vegetables during handling, transportation and storage. At present, post-production fungal spoilage is predominantly controlled by using synthetic fungicides. Under the global climate change scenario and with the need for sustainable agriculture, biological control methods of fungal diseases, using antagonistic microorganisms, are emerging as ecofriendly alternatives to the use of fungicides. The potential of microbial antagonists, isolated from a diversity of natural habitats, for postharvest disease suppression has been investigated. Postharvest biocontrol systems involve tripartite interaction between microbial antagonists, the pathogen and the host, affected by environmental conditions. Several modes for fungistatic activities of microbial antagonists have been suggested, including competition for nutrients and space, mycoparasitism, secretion of antifungal antibiotics and volatile metabolites and induction of host resistance. Postharvest application of microbial antagonists is more successful for efficient disease control in comparison to pre-harvest application. Attempts have also been made to improve the overall efficacy of antagonists by combining them with different physical and chemical substances and methods. Globally, many microbe-based biocontrol products have been developed and registered for commercial use. The present review provides a brief overview on the use of microbial antagonists as postharvest biocontrol agents and summarises information on their isolation, mechanisms of action, application methods, efficacy enhancement, product formulation and commercialisation.

Potential modes of action of Pseudomonas fluorescens ZX during biocontrol of blue mold decay on postharvest citrus

“…5 Therefore, more emphasis should be placed on the use of non-antibiotic-producing antagonists to control postharvest decay caused by fungal pathogens. 11 Conversely, our isolate of P. fluorescens ZX may not have the ability to produce antibiotics since antibiotics can extremely inhibit the growth of pathogens even at very low concentrations. Meanwhile, no molecular evidence for genes coding for the antibiotics DAPG, PCA, Prn, Plt or HCN was obtained by PCR.…”

“…What is worse, an antagonist depending on secretion of antibiotics may gradually lose its efficiency in late storage period of fruits . Therefore, more emphasis should be placed on the use of non‐antibiotic‐producing antagonists to control postharvest decay caused by fungal pathogens . Conversely, our isolate of P. fluorescens ZX may not have the ability to produce antibiotics since antibiotics can extremely inhibit the growth of pathogens even at very low concentrations.…”

“…Recently, interest in microbial biocontrol agent development has grown. In comparison to chemical fungicides, biological control is an approach to inhibiting pathogen growth and spread that is considered both safe and environmentally friendly . In addition, biocontrol agents can combat fungal pathogens using multiple modes of action, making the development of resistance by pathogens unlikely …”

“…In comparison to chemical fungicides, biological control is an approach to inhibiting pathogen growth and spread that is considered both safe and environmentally friendly. 10,11 In addition, biocontrol agents can combat fungal pathogens using multiple modes of action, making the development of resistance by pathogens unlikely. 12 Over the past two decades, a large number of candidate biocontrol agents, including Bacillus subtilis, 13 Pseudomonas spp., 14 Kloeckera apiculate, 15,16 Pichia membranefaciens, 1 Hanseniaspora uvarum 17 and Rhodosporidium paludigenum, 18 have been isolated from plant rhizosphere soil, fruits and leaf surfaces and reported to be effective at managing fungal diseases of postharvest citrus fruits.…”

Effect of Ulvan on the Biocontrol Activity of Debaryomyces hansenii and Stenotrophomonas rhizophila against Fruit Rot of Cucumis melo L.

“…The efficacy of biological control alternatives should be comparable to the level of control provided by conventional fungicides in order to obtain general acceptance [30]. Obtaining such high levels of control with biological control alternatives is difficult [15]. Thus, there is a tendency to promote an integrated system rather than a single one [31].…”