Field microbial application to foster food quality and safety

For centuries one of the great struggles to mankind’s survival was caused by the lack of sufficient food supplies. In the Western world this was overcome with the help of the Green Revolution in the 1950s and 60s, which led to the introduction of genetically improved high yielding crop varieties, new technologies and a new generation of chemical fertilizers, and synthetic herbicides and pesticides.

Though this increase of production led to the reduction of food insecurity and famine in the West, it was not without a cost. The abundant availability and consumption of highly refined wheat-based foodstuff led to a plethora of diet-related health issues. Plus, land was used more intensively and there was a growing reliance on and excessive use of chemicals, which led to risks such as food safety and environmental degradation.

As a result, we have seen an increased awareness and concern about these issues, and there is general consensus about the need to define and adopt agriculture alternatives that are more sustainable and environmentally friendly. Furthermore, the recent COVID-19 pandemic has led to increasing doubts about possible impacts of intensive, non-sustainable agriculture on the general equilibrium of man, animals, nature. One possible alternative is offered by microorganisms. By understanding and exploiting their role and mechanisms, microorganisms have the potential to reduce chemical input, and increase the quality and safety of harvested yields and processed foodstuff. While at the same time implementing the provision of ecosystem functions beneficial for the environmental and human health.

With COVID-19 now spreading, the global food system will be subjected to a radical rethink and how to produce our food will be extremely relevant. Microbiome solutions provide inputs for thought on redesigning our food value chains in a radical way in order to make them more resilient to crises connected with global markets and societies. The use of beneficial microbes for improving, not only plant growth and yield, but also the nutrient quality of crops, as WP2 of SIMBA project suggests, represents a promising tool that may respond to the challenges for modern agriculture. An improved, modified, post-COVID-19 agriculture will also require a more respectful attitude towards the naturality in our agroecosystems.

How to identify the best microbes for sustainable agriculture?

The use of efficient inoculants is considered an important strategy for sustainable management and for reducing chemical inputs in agriculture. Plant Growth-Promoting Microbes (PGPM) are important determinants of soil fertility and plant health, they have potential to improve crop productivity and nutritional quality. PGPM can also support resistance to plant pathogens and support plant tolerance to abiotic stresses. It is highly promising that a well-designed application of natural microorganisms and organic amendments can substitute at least in part for chemical fertilisers, insecticides and fungicides. However, in farm settings there are numerous biotic and abiotic factors may hinder their plant growth-promoting efficacy and reproducibility, limiting their successful use in agriculture.

When considering inoculation with PGPM, the first objective is to find the best bacteria available and to identify the best delivery method which determines the potential success of the inoculant. Most approaches for plant growth promotion imply the use of a single bacterial species as biofertilizer while to date only few consider a consortium of selected microorganisms. But mixed inoculants (the combination of two or more microbial species) that interact synergistically are currently being devised. Co-inoculation has high potential because it frequently increases growth and yield, provides the plants with more balanced nutrition, and improves absorption of nitrogen, phosphorus, and mineral nutrients.

The role of the SIMBA project

In our current research within SIMBA project, we aim to exploit the full potential of PGPMs for sustainable crop production by optimising the efficacy and reproducibility of field applications.

Figure 1 showing the flow-chart and relative tasks of WP2 and links to other WPs in SIMBA

This research builds on pre-existing knowledge of PGPMs associated with maize, wheat, potato and tomato in order to identify efficient microbial formulations to be applied as inoculants in arable crops in Italy and Germany.

Two types of approaches were taken into-account to obtain microbial consortia for sustainable agriculture: i) identification and synthetic assemblage from scratch by combining several isolated PGPMs with different functions (bottom-up approach) followed by the in vitro analysis of their ability to coexist, or ii) obtainment of complex microbial communities from environmental sample (top-down approach).

Figure 2 definition of microbial consortia: experimental design

Following these two types of approach, three microbial consortia, composed by compatible bacteria and fungi isolates, were identified, and a cluster of four bacteria isolated from maize seedling leaves, displaying synergistic biofilm formation properties, was characterised and adopted.

The outputs of greenhouse and growth-chamber experiments are expected to provide useful indications for work follow-up.

WP2 in the SIMBA project is researching the improvement of PGPMs field applications efficacy and reproducibility

Annamaria is Head of the ENEA Laboratory for AgriFood Sustainability, Quality and Safety and Professor of AgroFood Microbiology, Master’s Degree in Food Science and Human Nutrition, at University Campus Bio-Medico of Rome, Italy. Her research interests include agro-food microbiology, characterization and biodiversity of soil-root-food microbiome, plant growth-promoting microbes and plant-microbe interactions.

Contact her: annamaria.bevivino@enea.it