Dry formulations of the biocontrol agent Candida sake CPA-1 using fluidised bed drying to control the main postharvest diseases on fruits

Biotechnological development of Trichoderma-based formulations for biological control

Trichoderma spp. are a genus of well-known fungi that promote healthy growth and modulate different functions in plants, as well as protect against various plant pathogens. The application of Trichoderma and its propagules as a biological control method can therefore help to reduce the use of chemical pesticides and fertilizers in agriculture. This review critically discusses and analyzes groundbreaking innovations over the past few decades of biotechnological approaches to prepare active formulations containing Trichoderma. The use of various carrier substances is covered, emphasizing their effects on enhancing the shelf life, viability, and efficacy of the final product formulation. Furthermore, the use of processing techniques such as freeze drying, fluidized bed drying, and spray drying are highlighted, enabling the development of stable, light-weight formulations. Finally, promising microencapsulation techniques for maximizing the performance of Trichoderma spp. during application processes are discussed, leading to the next-generation of multi-functional biological control formulations. KEY POINTS: • The development of carrier substances to encapsulate Trichoderma propagules is highlighted. • Advances in biotechnological processes to prepare Trichoderma-containing formulations are critically discussed. • Current challenges and future outlook of Trichoderma-based formulations in the context of biological control are presented.

Insight into a Successful Development of Biocontrol Agents: Production, Formulation, Packaging, and Shelf Life as Key Aspects

Biocontrol agents (BCAs) have been proposed and studied over recent decades as a suitable alternative to diminish or substitute synthetic fungicides used to control pre- and postharvest diseases. However, the development of BCAs has many constraints and obstacles that would have to be overcome before they could be successfully implemented in the market. For the BCA commercial development, the microorganism should be mass-produced on a large-scale, and, independently of the method used for the production, a particular plan regarding the formulation of BCAs by multidisciplinary approaches (liquid or solid) is required to optimize the yield, efficacy, and shelf life of the developed product. Unfortunately, not all BCAs can survive the conditions imposed during the formulation process. Improved stability can be achieved by either using special conditions during growing or by adding protective substances to the formulation medium. Finally, BCAs should be formulated in such a way as to guarantee long-term stability and ease of application of the product. Therefore, an accurate range of the packaging conditions should be considered to extend the shelf life of the formulated product, preferably up to two years. Herein, we discussed the main aspects regarding the production, formulation, packaging, and shelf life of BCAs.

Formulation of the biological control yeast Meyerozyma caribbica by electrospraying process: effect on postharvest control of anthracnose in mango (Mangifera indica L.) and papaya (Carica papaya L.)

BACKGROUND

Microorganism for biological control of fruit diseases is an eco-friendly alternative to the use of chemical fungicides.

RESULTS

This is the first study evaluating the electrospraying process to encapsulate the biocontrol yeast Meyerozyma caribbica. The effect of encapsulating material [Wey protein concentrate (WPC), Fibersol® and Trehalose], its concentration and storage temperature on the cell viability of M. caribbica, and in vitro and in vivo control of Colletotrichum gloeosporioides was evaluated. The processing with commercial resistant maltodextrin (Fibersol®) 30% (w/v) as encapsulating material showed the highest initial cell viability (95.97 ± 1.01%). The storage at 4 ± 1 °C showed lower losses of viability compared to 25 ± 1 °C. Finally, the encapsulated yeast with Fibersol 30% w/v showed inhibitory activity against anthracnose in the in vitro and in vivo tests, similar to yeast fresh cells.

CONCLUSION

Electrospraying was a highly efficient process due to the high cell viability, and consequently, a low quantity of capsules is required for the postharvest treatment of fruits. Additionally, the yeast retained its antagonistic power during storage. © 2021 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.

Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables

Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approach. Biological control refers to postharvest control of pathogens using microbial cultures. With respect to application of biological control for increasing the shelf-life of food, the term biopreservation is favored, although the approach is identical. The methods for screening and development of biocontrol agents differ greatly according to their intended application, but the efficacy of all current approaches following scale-up to commercial conditions is recognized as insufficient. The combination of biological and physical methods to maintain quality has the potential to overcome the limitations of current approaches. This review compares biocontrol and biopreservation approaches, alone and in combination with physical methods. The recent increase in the use of meta-omics approaches and other innovative technologies, has led to the emergence of new strategies to increase the shelf-life of fruit and vegetables, which are also discussed herein.

Verifying the biocontrol activity of novel film-forming formulations of Candida sake CPA-1: resilience in relation to environmental factors, rainfall episodes, and control of Botrytis cinerea on different hosts

BACKGROUND

The efficacy of Candida sake CPA-1 as a biocontrol agent against several diseases has been studied since it was isolated 20 years ago. However, it was only recently that two suitable and effective film-forming formulations based on potato starch and maltodextrins were developed using the fluidized-bed spray-drying system. The present work aimed to confirm the capability of both novel formulations by testing their resilience on grapes at different temperatures (0, 22, and 30 °C), relative humidities (40% and 85%), and simulated rainfall levels. Another objective was to examine the control of Botrytis cinerea in different hosts.

RESULTS

The CPA-1 cells from both dried formulations survived better than the liquid formulation on grapes stored at 0 and 22 °C regardless of the relative humidity. After simulated rainfall, potato starch formulation achieved significantly higher populations than maltodextrin formulation, although the highest reduction was -1.6 log N N₀ ^-1 . A positive effect of cell establishment prior to the simulated rainfall was shown, and recovered cells from the potato starch formulation were significantly higher after 72 h of cell establishment. Finally, both formulations reduced the incidence and severity of B. cinerea on pears, apples, and tomatoes.

CONCLUSION

The potential of these novel film-forming formulations of C. sake CPA-1 was verified. The resilience of formulated C. sake was better than the commercialized liquid formulation, the adherence of the formulations to the grapes improved after an establishment period prior to rain exposure, and the control of B. cinerea was verified in a wider range of hosts. © 2019 Society of Chemical Industry.

Novel film-forming formulations of the biocontrol agent Candida sake CPA-1: biocontrol efficacy and performance at field conditions in organic wine grapes

BACKGROUND

The biocontrol agent (BCA) Candida sake CPA-1 has previously effectively reduced Botrytis bunch rot (BBR) and it was also suggested as a promising strategy to control sour rot in grapes under field conditions. However, biocontrol efficacy of solid formulations of CPA-1 has never been tested in field trials. The present study aims to confirm the efficacy against BBR and sour rot in grapes under field conditions of two novel formulations recently developed by the addition of biodegradable coatings using a fluidized-bed spray-drying system.

RESULTS

Novel film-forming formulations of the BCA C. sake CPA-1 controlled B. cinerea as well as liquid formulation. Sour rot control resulted better in the second season and severity reductions were more satisfactory than incidence control. Visual and cryoSEM observations revealed that film-forming treatments were uniformly distributed on plant surfaces. CPA-1 coating could be observed on grapes at harvest time.

CONCLUSION

The results of this work suggest that solid formulations would be a competitive alternative to conventional fungicides because they were easy to package and transport, and cell viability could be maintained for a long period of time. © 2018 Society of Chemical Industry.

Surfactant effects on wettability of Penicillium frequentans formulations to improve brown rot biocontrol

BACKGROUND

Penicillium frequentans can be used in the management of brown rot caused by Monilinia spp. Competition is the primary mode of biocontrol activity of P. frequentans, which must therefore cover most of fruit surface to avoid pathogen infection. Our objective was to optimize the efficacy of P. frequentans by maximizing fruit surface coverage and retention with the antagonist formulation by surfactant incorporation.

RESULTS

Sixteen surfactants were assessed for the management of brown rot at 3-5 different concentrations. Nine surfactants increased the droplet surface up to 2.5 times compared with water on an inert surface, with or without the presence of P. frequentans in each drop. Eight surfactants increased P. frequentans on the fruit surface, enhancing colony forming units after run off or lateral spray application uptake by 50% compared to the control without surfactants. But only some doses of sodium carboxymethyl cellulose, gelatin, Tween 20, sorbitan alkyl esters, synthetic latex, polyethylene glycol isotridecyl ether, and hydroxypropyl methylcellulose could show the same covered fruit surface after run off or lateral spray application. There were also no phytotoxic side-effects on five different species of stone fruit.

CONCLUSIONS

The efficacy of P. frequentans dry conidia can be enhanced by optimizing the composition of the formulation with surfactants. © 2018 Society of Chemical Industry.