Microbial Biofertilizers to Bolster Food Security
Everyone eats—animals, plants, even microbes need food. Today, there are more than 8 billion people on Earth, all of whom need food to eat. But producing that much food is difficult. In addition, the United Nations expects the human population to increase by nearly 2 billion in the next 30 years, which makes food security a looming global issue for humanity.
Besides a rapidly growing population, climate and environmental change pose a threat to food security worldwide. Warmer temperatures facilitate the spread of pathogens that lower crop production, increase food spoilage and lead to higher risk of foodborne illness. Extreme weather brings floods, droughts and storms that strip agricultural soil of nutrients, damage plants and spread plant pathogens, which, in turn, reduces food yields.
Fortunately, microbes offer sustainable innovations to meet the nutritional needs of an expanding global population. The addition of specific microbes to natural and agricultural ecosystems can promote increased resiliency and productivity. These microbial solutions will be especially important to counteract stress from changes in temperature, precipitation and disease resulting from climate change. Thus, microbial solutions for ecosystems and food systems can have big results for humanity's food security.
The Role of Microbes in Food Production
The health and function of any environment is closely tied to the collection of microbes living in it, known as its microbiome. "Microbiomes are the invisible engines of life—they drive nutrient cycles, influence health, support biodiversity and stabilize ecosystems," said Raquel Peixoto, Ph.D., professor at King Abdullah University of Science and Technology, Saudi Arabia. Peixoto's research focuses on using microbial therapies to increase host resilience to climate-induced stressors. Agricultural crops are heavily influenced by their microbiome. Microbes found on the leaves, stalks and roots of the plants, as well as the surrounding soil, affect how well a plant reacts to stress, absorbs nutrients and grows.
Farmers have long appreciated the role of microbes for promotion of crop production. In 1904, the scientist Lorenz Hiltner first described the "rhizosphere" as the collection of soil microbes and nutrients that surround plant roots and are important for plant growth and health. A key role for microbes in the rhizosphere, called the rhizobiome, is nutrient cycling. Nitrogen and phosphorus can be limiting nutrients in soils, thereby restricting or "limiting" the growth of a plant. To overcome this limitation, plants and microbes form symbiotic relationships to increase nutrient availability. For example, soil bacteria known as rhizobia colonize plant roots and fix nitrogen for the plant to use, while fungi of the Glomeromycota phylum enhance root uptake of water, phosphate and nitrogen. The rhizobiome also helps to modulate plant defenses and resilience to stress through the production of plant hormones called phytohormones.
Environmental change can alter a plant's rhizobiome. Changes in temperature, precipitation, salt and nutrient levels are associated with shifts in microbial community structure and biodiversity. Peixoto pointed out that climate change causes a decline in biodiversity, which can lead to a higher prevalence of plant pathogens and lower plant productivity. To counteract these effects, she advocates for restoring beneficial microbial communities that promote crop growth and yield. Peixoto emphasized that by doing so, "we can protect and, consequently, enhance ecosystem resilience, which is essential not just for ecology, but also for food security and the global climate system that supports all life on Earth."
Biofertilizers: Microbial Probiotics to Promote Plant Growth
Adding probiotics is a way to restore beneficial microbial communities to the soil. "Biofertilizers" are communities of microorganisms (bacteria and/or fungi) that are applied to soils, seeds and/or plants to promote plant growth. Ultimately, these probiotic mixtures of plant growth-promoting microbes can be used to enhance plant resilience and promote food security. Each plant and soil type has a different microbiome, so biofertilizers are optimized for crop type and region. Scientists like Dilfuza Egamberdieva, Ph.D., professor and head of the Biological Research and Food Safety Lab at the National Research University (TIIAME), Uzbekistan, develop unique combinations of microbes that are most effective for each plant based on its rhizobiome. "Through my research on beneficial microbes—those that enhance plant growth, improve soil health and contribute to long-term carbon sequestration—I aim to develop sustainable agricultural practices," said Egamberdieva. In practice, biofertilizers help promote plant growth in multiple ways. For example, they can enhance nutrient availability, introduce phytohormones and/or boost defenses against pathogens.
Enhancing Nutrient Availability
Some microbial species improve nutrient availability for plants. Bacillus species, which are commonly found in soils, can solubilize potassium and organic and inorganic phosphorus in soil. For tobacco plants, inoculation with a strain of Bacillus increased available soil potassium and phosphorus levels by more than 30% compared to untreated controls, resulting in significantly longer root systems, taller plants and increased crop yield. The same bacterial strain enriched soil nutrient content and crop production for wheat, corn and peanut crop systems as well. Bacteria can also be used to improve the availability and uptake of nitrogen, as demonstrated by the work of ASM member Mariangela Hungria, M.S., Ph.D.—a scientist at the Brazilian Agricultural Research Corporation (EMBRAPA) and 2025 World Food Prize Laureate—who has developed various microbial inoculants that enhance nitrogen fixation and reduce the need for synthetic fertilizers in major crops like soybeans and common beans.
Other microbes produce siderophores that bind iron found in the soil and deliver that iron to plants in a usable form, promoting growth. Microbial siderophores produced by strains of Pseudomonas aeruginosa increased the iron transport to maize plants for a higher crop yield. Zinc, another necessary metal for plants, can also be limited in soil. Strains of Azospirillum, Rhizobium and Bacillus are all known to solubilize zinc in the soil for easier uptake by wheat plants.
Producing Phytohormones
Another direct effect of microbes on plant growth is the production of phytohormones that mediate plants' response to stress. Phytohormones regulate plant cell division and growth, tissue differentiation, immunity to pathogens and abiotic stress from changes in salinity, precipitation and temperature.
Indole-3-acetic acid (IAA) is one of the most common plant hormones, and microbial production of IAA has been associated with increasing drought and salt stress. For example, production of IAA by Streptomyces strains was associated with increased water stress tolerance in wheat plants. These and other examples serve as proof of concept that microbial-produced phytohormones can promote plant stress tolerance.
Boosting Defenses Against Pathogens
Microbes in biofertilizers can also indirectly promote growth by increasing plants' defenses to pathogens. Some microbes produce antimicrobial molecules to ward off diseases. For example, the fungus Aspergillus cvjetkovicii protected rice against infections with Rhizoctonia solani, the causative agent of root and stem rot, by releasing a signaling metabolite that inhibits pathogenic gene transcription. Other microbes act as biocontrol agents that outcompete pathogens for nutrients or induce plant defenses. Plants inoculated with strains of Streptomyces were protected against infection from multiple fungal plant pathogens. According to Egamberdieva, "many farmers are struggling as they face annual losses in crop production due to plant pathogens, challenges that are being intensified by climate change and cannot be effectively controlled by agrochemicals." Probiotic biofertilizers help increase the resilience of plants to disease.
Limitations of Biofertilizers and How to Overcome Them
Use of biofertilizers is growing worldwide. Several companies currently sell commercial biofertilizers, and the global biofertilizer market is anticipated to grow 12% annually. North America has the largest share of the biofertilizer market, driven by demand for organic produce and more sustainable agricultural practices. However, there are limitations to commercial biofertilizers. They have a shorter shelf life and are more difficult to scale production than synthetic fertilizers. These factors can make biofertilizers more expensive or less effective when applied to crops compared to synthetic fertilizers. Also, farmers are hesitant to change their agricultural procedures if those changes may result in lower crop yield or profitability. Scientists are working to improve biofertilizer efficacy and stability. One approach is adding biochar.
Biochar to Support Biofertilizer Microbes
Biochar is the lightweight residue of burning organic matter. Organic waste, such as crop residue or manure, is burned with limited to no oxygen, resulting in carbon-rich biochar. Burning the waste, instead of letting it decompose and release greenhouse gases, locks the carbon into stable compounds that take much longer to decompose. This helps sequester carbon in soil and mitigate greenhouse gas emissions.
Applying biochar directly to soils is known to improve soil health, soil moisture capacity and can bind heavy metals and chemicals to clean up contaminated soils. The addition of biochar to soil also improves nutrient availability, which is linked to enhanced plant growth and improved crop yield in field experiments. Biochar has been used in agriculture for more than 2,500 years as a nutrient additive, but it has gained recent popularity in the push for sustainable agricultural practices and increased food security.
Egamberdieva is particularly excited about expanding on biochar's positive impacts on soils by combining biochar with microbial technologies to promote sustainable agriculture. Biochar can act as a carrier for plant growth-promoting microbes. Its porous structure and high water and carbon content provide necessary nutrients for biofertilizer microbes. "When combined with beneficial microbes, biochar improves nutrient cycling, boosts soil fertility and enhances plant resilience to environmental stresses like drought and extreme temperatures. This innovative approach not only addresses the challenges posed by climate change, but also offers a practical, eco-friendly solution for sustainable farming practices and ecosystem restoration," Egamberdieva explained. Her research showed that the application of biochar with microbes led to higher soil microbial diversity and increased plant growth.
Application of biochar can also limit plant pathogens. Biochar-treated tobacco plants had lower incidence of a fungal pathogen. The biochar both directly exerted an antifungal effect and indirectly influenced the rhizosphere microbial community to produce antimicrobial molecules against the pathogen. Biochar in combination with biofertilizer inoculants can improve plant productivity and help prevent plant diseases.
Microbes for Sustainable Agriculture
Probiotic microbes can reduce agricultural greenhouse gas emissions to make agriculture more sustainable. Synthetic nitrogen fertilizers are energy-intensive to produce, accounting for more than 10% of agricultural greenhouse gas emissions and 2.1% of global greenhouse gas emissions. "Microbial-based biofertilizers reduce the reliance on synthetic fertilizers, thereby lowering nitrogen emissions, while also enhancing soil health," Egamberdieva said. Scientists like Egamberdieva and Hungria are helping to make farming more sustainable by using microbes. For example, Hungria's work in Brazil has contributed to widespread use of biofertilizers, which is estimated to have prevented the release of 230 million metric tons of CO2-equivalent emissions.
Biofertilizers can directly mitigate emissions from agricultural soils. For instance, tomato plants inoculated with a biofertilizer had increased plant growth and emitted 38-76% less nitrous oxide (N2O) compared to control plants lacking the inoculant. Addition of the biofertilizer was correlated with alterations to soil microbial community structure and abundance of key nitrogen-cycle functional genes, which may lead to less substrates for N2O-producing microbes and therefore decreased emissions.
Biochar can directly sequester greenhouse gases, such as CO2 and N2O, because of its porous structure. When added to rice and maize fields, biochar application resulted in a 47-57% reduction in CO2 emissions compared to controls. Biochar addition also modifies soil microbial communities that, in turn, emit less greenhouse gas. Together, biofertilizers and biochar act as sustainable innovations to improve global food production.
The Future of Biofertilizers
The outlook for biofertilizers is promising. They not only improve crop yield and reduce the abundance of plant pathogens, they also make plants more resilient to climate stress. Inoculation formulations can be tailored to local conditions, making biofertilizers adaptable to a wide range of crops and climates around the world. In addition, the use of biofertilizers with biochar reduces the amount of synthetic fertilizer needed, lowering greenhouse gas emissions and cutting costs for farmers. "What excites me most is that these innovations not only work—they are sustainable, ecologically friendly, cost-effective and globally applicable. They allow us to collaborate with nature, rather than fight against it, to build a livable future," Peixoto said. Thus, microbes in biofertilizers provide tremendous opportunities to help humanity improve food security in the face of climate change.
According to Rino Rappuoli, Ph.D., scientific director at the Fondazione Biotecnopolo di Siena, Italy, "Microbes hold the missing ingredient needed for the next climate breakthroughs." Rappuoli, who is also the President of the International Union of Microbiological Societies (IUMS), views microbes as solutions to many of humanity's greatest challenges. To showcase microbial innovations, such as biofertilizers, IUMS partnered with ASM to convene a scientific advisory group of global experts to identify concrete microbial solutions for climate change. The group’s report outlined innovative microbial technologies that can significantly contribute to climate change mitigation and adaptation, highlighting the use of probiotic microbes for food security and ecosystem resilience. A complementary editorial underscores the urgent need for coordinated global action across nations and sectors to address climate change, including incorporating microbes into innovations to tackle the global crisis. "We encourage leaders of climate initiatives across all sectors to incorporate microbial processes into climate research and sustainable solutions," Rappuoli said.
Today's food systems will not meet the demands of tomorrow’s population. Probiotic biofertilizers and biochar can be used to bolster global food security. Microbes are potential solutions to meet the urgent need to feed a growing population in a sustainable manner.
Author: Rachel Burckhardt, Ph.D.
In This Issue
- Microbial Biofertilizers to Bolster Food Security
- How Studying Bat Viruses Can Help Prevent Zoonotic Disease
- Agnostic Diagnostics and the Future of ASM Health With Dev Mittar
- Leveraging Cannabinoids as Antimicrobials
- Fecal Microbiota Transplants: Past, Present and Future
- ASM's Young Ambassadors Use Science to Empower Communities
- How Do Microbes Remove Radioactive Waste?
- How Microbiomes Frame Humanity's Role on Earth