H2020 BacBio Project: Mechanistic and functional studies of Bacillus biofilm assembly in plants and its impact on sustainable agriculture and food security
- Type Project
- Status Filled
- Execution 2015 -2021
- Assigned Budget 1.453.562,5 €
- Scope Europeo
- Main source of financing H2020
- Project website BACBIO
To ensure a healthy environment, economic profitability, and socioeconomic equity, it is crucial to promote and implement more sustainable agricultural methods. This involves exploring innovative approaches. Funded by the European Research Council, the BacBio project seeks to investigate the potential of beneficial microbes (biofilms) as a partial substitute for pesticides, while mitigating the risk of contamination by human pathogens.
BacBio will employ various strategies to study the feasibility of using beneficial microbes for plant protection. It will focus on two closely related organisms with contrasting functions: Bacillus subtilis, which protects plants; and Bacillus cereus, which is pathogenic to humans. By analyzing the chemical differences in their extracellular matrices, BacBio seeks to advance our understanding of the interactions between bacteria and plants.
- 1. We have been able to describe at the atomic level the main differences between the amyloid protein of two related bacilli (B. subtilis and B. cereus), which seems to determine their functionality in plant ecology.
- 2. We have also found a diversification of the functions of the extracellular matrix (ECM) in its interaction with the environment. This interaction, whether chemical (signaling) or structural, allows for the establishment of stable bacterial communities in plants or beneficial communication between kingdoms.
- 3. We have discovered that the primary function of B. subtilis amyloid is to provide cell membrane integrity as cells enter the stationary phase of growth, in addition to its role in biofilm assembly. These two functions affect persistence and antagonistic interactions with pathogenic fungi.
- 5. Different plant surfaces possess distinctive morphological and chemical characteristics that modulate the ecology of bacilli and the expression of biofilm-related genes.
- 6. The ability of B. cereus to induce intestinal damage is based, alternatively, on the persistence of vegetative cells in plants.
This contributes to the maintenance of other ecological properties, such as biofilm formation. These findings represent a breakthrough in the true role of bacterial biofilms in plant bacterial ecology and in their management to enhance their beneficial contribution to crop health. Therefore, from an applied perspective, our findings can readily be translated into improved implementation of microbes and derived molecules within sustainable crop protection product production programs.
The study of B. cereus has revealed that, beyond spores and toxins, it is important to pay attention to vegetative cells, which can cause a wide variety of symptoms in humans, from diarrhea or vomiting to death, necessitating a review of the procedure used for their detection. These findings have been disseminated among the scientific community through research articles or presentations at seminars and conferences.
One of the main concerns in agricultural biotechnology is the management of microbial diseases in plants. Treating these diseases involves the use of pesticides (fungicides, bactericides, nematicides); however, overuse of this approach threatens environmental health. Furthermore, the presence and prevalence of microbes in fruits and vegetables, which are causative agents of human disease, constitutes a significant problem that not only negatively impacts public health but also contributes to food industry contamination.
All of these problems contradict the concept of sustainability, which guides policies in agriculture and the food industry, and require prioritizing the development of innovative and successful strategies that reduce environmental damage and public health while maintaining product quality and benefits. In our project, we work with the beneficial bacterium Bacillus subtilis and the phylogenetically related species Bacillus cereus, which includes pathogenic strains. Both microbes are capable of forming biofilms that serve to protect bacterial cells from external aggressions, among other functions.
To propose viable strategies aimed at promoting biofilm formation and, therefore, a positive effect of beneficial bacteria, while simultaneously slowing or preventing the establishment of pathogens, it is important to understand the bacterial factors involved in this development program and to search for specific targets.
In our project, we are interested in the following specific objectives: 1. To understand the process of amyloidogenesis. To address this issue, we propose switching between in vitro and plant conditions, using a variety of techniques, including chemistry, biophysics, and cell biology. 2. To understand how plants modulate biofilm formation, with special emphasis on the effect on amyloids, and reciprocally, how the plant responds to the establishment of such communities. 3. To investigate how the two bacterial species communicate with each other or even with other species that may coexist in the same habitat.
Sustainable agriculture is an ambitious concept conceived to improve productivity while minimizing side effects. Why does the effectiveness of a biocontrol agent vary so much? How can different therapies be efficiently and combined to combat microbial diseases? These are questions that require research to be addressed with sustainability criteria.
What I present is a comprehensive proposal that aims to study microbial ecology and specifically bacterial biofilms as the central axis of two differential but probably interconnected scenarios in plant health: i) the beneficial interaction of the biocontrol agent (BCA) Bacillus subtilis, and ii) the unconventional interaction of the foodborne pathogen Bacillus cereus.
I will start working with B. subtilis, and the reasons are: 1) Different isolates are promising BCAs and are marketed for that purpose, 2) There is extensive information on the genetic circuits that govern important aspects of B. subtilis physiology such as antibiotic production, cell differentiation and biofilm formation.
In parallel, I propose to study how B. cereus, a foodborne pathogenic bacterium, interacts with plants. I plan to establish a multidisciplinary approach that will combine genetics, biochemistry, proteomics, cell biology, and molecular biology to visualize how this bacterial population interacts and communicates with plants and other microorganisms, and how all these factors trigger or inhibit the developmental program that leads to biofilm formation.
I am also interested in whether structural components of the bacterial extracellular matrix (exopolysaccharides or amyloid proteins) are important for bacterial fitness. If this is the case, I will also investigate what external factors affect their expression and assembly into functional biofilms. The insights gained in these studies are committed to advancing our understanding of microbial ecology and its biotechnological applicability to sustainable agriculture and food security.
Our project is based on the principle of merging disciplines, which aims to exponentially expand our knowledge of the questions we seek to answer. One of the most attractive elements involved in biofilm assembly is amyloid proteins, widely distributed in nature and with diverse functions. The combination of organic and analytical chemistry with biophysics and biochemistry has allowed us to discover differences in fiber formation. We believe our research has a significant impact on cell and structural biology, as well as on agricultural biotechnology and biomedicine. We have been able to validate the accumulated knowledge in in vitro studies of plant biofilms, making a decisive contribution to the foundations of microbial ecology.
It's clear that bacteria use a variety of factors to live and communicate with plants, and we've expanded our knowledge in this area. Furthermore, our research also demonstrates the importance of the host plant, not only immunologically, but also metabolically and structurally (topologically). Like humans, plants possess an immune system that responds to external insults or changes, one of which is the bacterial communities they live with.
The final outcome, the development of the disease or the establishment of the pathogen, will be the result of a complex network of interactions and dialogues between all the actors: plant pathogens, beneficial pathogens, and human pathogens. The combination, once again, of disciplines such as plant microbiology and physiology with cutting-edge analytical chemistry techniques and diverse OMICS has decisively contributed to the success of these studies and has provided interesting conclusions and novel hypotheses.
In all of these studies, we are moving from the behavior of bacterial populations to the actual visualization of changes, and then embarking on more detailed and specific studies at the cellular or individual level. In short, our project has provided answers to basic questions about microbial cell biology and physiology, allowing us to truly understand, from a more holistic perspective, how they coordinate to generate a response in the context of their interaction with plants. This knowledge would be used to: 1) develop more robust and feasible biological control strategies aimed at reducing the use of chemicals, either alone or in combination with other management strategies within the context of sustainable practices; and 2) contribute to eradicating or preventing the establishment of human pathogen communities on ready-to-eat fruits or vegetables that are responsible for human diseases.
- UNIVERSIDAD DE MALAGA (UMA)
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