Bacillus
- Also known as
- Bacillus spp., Bacillus subtilis, Bacillus amyloliquefaciens
Bacillus is a genus of rod-shaped, spore-forming bacteria common in soil. Selected strains of species such as Bacillus subtilis and Bacillus amyloliquefaciens are widely used in agricultural biologicals to promote plant growth, improve nutrient availability and suppress plant diseases.
What is Bacillus?
Bacillus is a large genus of bacteria found in soil, water and on plants. Its members are rod-shaped, and many can form endospores: dormant, highly resistant cells that survive heat, drying and chemicals and can revive when conditions improve. That survival ability is a big part of why Bacillus is one of the most widely used groups of organisms in agricultural biological products.
How Bacillus strains help crops
Different species and strains do different things. Beneficial effects reported for agricultural Bacillus strains include:
- Plant growth promotion. Many strains act as plant growth-promoting rhizobacteria, producing plant hormones or otherwise stimulating root growth.
- Nutrient availability, including phosphorus solubilization.
- Disease suppression, by competing with pathogens and producing antimicrobial compounds, including lipopeptides such as surfactin, iturin and fengycin.
- Induced systemic resistance, priming the plant’s own defenses.
Some Bacillus products are registered as biopesticides for disease control, and others are sold as biostimulants or inoculants. Bacillus thuringiensis, known as Bt, is a separate, well-known case: its insecticidal proteins are used in biological insecticides and in insect-resistant crops.
Why Bacillus suits biological products
Because they form spores, Bacillus strains tolerate manufacturing, storage and application better than many other beneficial bacteria. They can be formulated as liquids, powders or seed treatments with long shelf lives, and they are compatible with many farming practices.
Bacillus at Locus
Locus lists Bacillus among the genera it uses in its agricultural biologicals, and its Rhizolizer Prime System combines rhizobia with Bacillus and Trichoderma in a multi-strain soybean system.
Frequently asked questions
The agricultural species used in crop products are generally regarded as low risk and are reviewed by regulators. The genus also includes Bacillus anthracis and Bacillus cereus, which can cause illness, which is why products rely on specific, characterized strains.
B. subtilis strains are mainly used for plant growth promotion and disease suppression. B. thuringiensis produces proteins toxic to certain insects and is used as a biological insecticide.
Sources
- Bacillus-based biological control and plant growth promotion, Peer-reviewed reviews (e.g. Frontiers in Microbiology)
- Biopesticides registered active ingredients, U.S. Environmental Protection Agency