Application

The control of soil-borne pathogens by biological control is not a new idea and has been studied since the early twentieth-century [4]. For a long time commercial applications were thought to be not feasible but, in the last decades techniques for application progressed tremendously.

For BananaGuard, we believe that distributing the final product via drip irrigation is the best method. In drip irrigation a network of pipes is used that has emission points (drippers) delivering the water in a precisely measured volume into the rhizosphere. Distribution of growth substances such as fertilizers and chemicals, such as herbicides and fungicides, has been shown to be successful before [5, 6]. In 2008, Boari et al. showed that distribution of suspensions containing small particles via drip irrigation shows great potential. When considering shelf live and transport as well as the fact that, in some growing regions, no mechanical irrigation is used, BananaGuard could be applied as dry products such as granules or powders as seen with comparable products [8]. Furthermore, these dry pelets can be stored for a longer time period. Since BananaGuard needs to be applied in a preventive manner rather than curative, usage of more dilute suspensions culture applied over a longer time period or repeated application of the dry product is conceivable. Seed coating can be considered when excluding the kill switch from the system. Colonization of the banana roots by BananaGuard at the very early seedling stage secures continuous protection.

Application of BananaGuard could possibly be combined with the application of products such as fertilizer. Since farmers generally already supplement their plants with fertilizer or pesticides, this would only add a small extra step to their current practices. The farmers can also grow the bacteria themselves with a minimal amount of materials and training, since P. putida is an easily grown bacteria as long as there is the possibility to work in sterile conditions. The bacteria can be harvested over a series of generations. However, new samples would need to be purchased to assure the quality of the product and to remove contamination that arise during harvesting.

Although the application would be simple, regulations concerning an engineered soil bacterium for bio-control are complex and different in most countries. With the current regulations in Europe, for example, application of our product would not be possible in the near future. Luckily, however, our main target area, South America and Asia have far less stringent rules about the use of GMO products. Combining the acceptance of GMO bacteria in most banana producing countries and maintaining availability of a “GMO free” banana makes our product a strong candidate for introduction into the global market.

With the rise of more highly engineered crops, whether created with traditional breeding or genetic modification, the inter-species diversity in crops grown commercially decreases. Even though it will not be as dramatic as is the case with bananas, crops will become less diverse and therefore weaker against threats they were not specifically selected for. Fusarium has been known to also infect other crops such as wheat, cucumbers and tomatoes. If successful, our system could be rapidly changed to work with other crops or even other fungus. Future applications could even include the production of plant growth promoters or increased nitrogen fixation in the soil. By combining the modularity and rapid modification time possible in bacteria but not plants, our system can be an efficient way to safeguard the crops of the future.