Nature's defense: Using Bacillus spp. to protect fruits and vegetables

Fresh fruits and vegetables are often plagued by postharvest diseases, resulting in significant food waste and economic losses. The FAO reports that approximately 45% of harvested fruits, vegetables, roots and tubers are lost, with much of this loss occurring during storage due to pest and pathogen infestation, adverse environmental conditions, and other factors. Chemical fungicides and preservatives have been used to control post-harvest spoilage, but these pose significant risks to human and animal health and the environment. In response, there is a growing demand for natural, friendly and biosecure methods to reduce post-harvest food losses. A promising approach is the use of plant growth-promoting bacteria (PGPBs), which can help promote plant growth, disease resistance, and abiotic stress tolerance without adverse effects. Bacillus spp. is a type of PGPB. It has been shown to be particularly effective in producing a wide range of bioactive compounds with an antibiotic activity that can help trigger defense responses in host plants. Bacillus spp. are also resistant to physical and chemical treatments, making them ideal for use in the development of natural crop protection products. Research has shown that this bacteria can protect various plant species against a wide range of biotic and abiotic stresses, including postharvest diseases. Studies have also shown that Bacillus spp. can improve fruit/vegetable quality, disease resistance, and tolerance to various conditions associated with handling, transport, and storage. However, the underlying mechanisms regulating fruit/vegetable storage quality and the role of Bacillus spp. in controlling postharvest diseases remain unknown. In 2019, the journal Plants published a review from the Bashkir Scientific Research Institute of Agriculture of the Russian Academy of Sciences. This review provides information on the many successful applications of Bacillus spp. in the control of various post-harvest pathogens of different fruits/vegetables during handling, transport and storage.? The following is a summary of its main findings. Bacillus spp. Capacity to Reduce Postharvest Losses of Fruits and Vegetables: Bacillus spp. can colonize the rhizosphere and phyllosphere of plants, where they promote plant growth and increase resistance to biotic and abiotic stresses. Bacillus spp. also produces a variety of secondary metabolites, including antibiotics and enzymes, which can inhibit the growth of pathogenic microorganisms and degrade plant cell wall components, respectively. Bacillus spp. has been shown to be effective in controlling postharvest losses of fruits and vegetables caused by various microorganisms, including bacteria, fungi, and yeasts. Mechanisms of Bacillus?spp.? The mechanisms by which Bacillus spp. reduce postharvest losses are diverse and include direct inhibition of pathogenic microorganisms through the production of antimicrobial compounds. Bacillus spp. can also reduce postharvest losses by stimulating plant defense mechanisms that reduce susceptibility to pathogenic microorganisms. Bacillus spp. may also produce enzymes that break down plant cell wall components such as pectin, which can cause fruit softening and rot. Applications of Bacillus?spp.? The use of Bacillus spp. to reduce postharvest losses is a promising alternative to chemical preservatives due to its natural origin and many benefits to plants and fruits. Bacillus spp. can be applied to fruits and vegetables as a biocontrol agent through various methods such as seed treatments, soil drenches or foliar sprays. Bacillus spp. can also be used in combination with other biocontrol agents or integrated with other post-harvest treatments to achieve greater efficacy. Challenges and Limitations of Bacillus?spp.? One of the main challenges in using Bacillus spp. to reduce postharvest losses is the variability in their effectiveness depending on the type of fruit or vegetable, the type of pathogen, and the environmental conditions. Another challenge is the need for further research into the optimal conditions for its use, including dosage, timing and method of application. Regulatory requirements for the use of Bacillus spp. as biocontrol agents are also a limitation, as they vary from country to country and can be time-consuming and costly. Conclusions and Future Prospects Bacillus spp. is a promising alternative for reducing postharvest losses due to its natural origin, many benefits, and potential for integration with other postharvest treatments. However, further research is needed to optimize its use for different fruits and vegetables and to develop standardized application methods and regulatory frameworks. Future studies should also focus on its effects on the microbial ecology of the phyllosphere and rhizosphere and its potential impact on human health and the environment. Author:?Jorge Luis?Alonso G. (with ChatGPT)?Maximizing Agribusiness Profits with Expert Postharvest Storage Strategies | Horticultural Writing Specialist.?This article was written exclusively for the business platform Postharvest. Cover photo:?Bacillus subtilis bacteria (Josef Reischig)