Towards new biofungicides: exploring Xenorhabdus and Photorhabdus bacteria for Botrytis cinerea management

The fungus Botrytis cinerea (Helotiales: Sclerotiniaceae) is a plant pathogen that primarily attacks mature plant tissues, inducing rotting of plant tissues and causing significant losses in fruit and vegetable production worldwide. Controlling Botrytis is expensive, and global expenses are estimated to exceed €1 billion per year. In the new paradigm of sustainability and resilience, it is crucial to find effective ways to control this pathogen that are environmentally friendly.

A new scientific study conducted by the IN-vid group of the Institute of Vine and Wine Sciences (ICVV) has explored the anti-Botrytis efficacy of different products obtained from the fermentation of entomopathogenic bacteria belonging to the genera Xenorhabdus and Photorhabdus (Morganellaceae). These bacteria are known to produce toxins with antifungal properties, among other actions.

The study focused on evaluating (i) unfiltered bacterial fermentates, (ii) cell-free supernatants of the fermentation, and (iii) the bacteria themselves isolated after fermentation (in the "free" form). The results have shown that the use of fermentate and supernatant produced by the bacteria X. nematophila inhibits nearly 100% of Botrytis growth on plates. Additionally, the application of the bacterium P. laumondii isolated after fermentation is capable of effectively controlling Botrytis growth under in vitro conditions, showing similar results to those obtained by applying the commercial biofungicide Bacillus amyloliquefaciens (Serenade® ASO fungicide).

These findings contribute to a better understanding of the effects of these bacteria against B. cinerea and can help develop an innovative formulation of these bacterial products as efficient biocontrol tools in agricultural production. This research was funded by the Ministry of Science and Innovation, grant PID2019-104112RB-I00 (MCIN/AEI/10.13039/50110001103) and by the Instituto de Estudios Riojanos (IER, Government of La Rioja, Spain, ref. 29/2022.

For more information:
Vicente-Díez, I., Carpentero, E., Pou, A., Campos-Herrera, R., 2023. Exploring bacterial cell-free supernatants, unfiltered ferments and crude bacteria uses of Xenorhabdus and Photorhabdus (Morganellaceae) for controlling Botrytis cinerea (Helotiales: Sclerotiniaceae). Biol. Control 183, 105259.