Brevibacillus laterosporus primarily serves as a “multifunctional guardian” in agriculture; it not only efficiently breaks down soil phosphorus to supplement crop nutrition but also secretes antimicrobial substances to inhibit various pathogens, thereby promoting crop growth and boosting yields.
Detailed Roles of Brevibacillus laterosporus in Agriculture
1. Promoting Plant Growth and Nutrient Uptake
Brevibacillus laterosporus directly promotes the healthy growth of crops through various mechanisms:
- Secretion of various hydrolytic enzymes: It secretes a variety of hydrolytic enzymes (such as phosphatases and proteases) that help break down macromolecules in the soil—such as organic phosphorus and proteins—converting them into forms that are easily absorbed by crops, thereby enhancing fertilizer utilization efficiency.
- Synthesis of plant growth hormones: Studies have shown that this bacterium can synthesize plant hormones—such as indole-3-acetic acid (IAA)—which directly stimulate root elongation and lateral root proliferation in crops, thereby enhancing the plant’s capacity to absorb water and mineral nutrients.
- Promoting nodulation in leguminous crops: For leguminous crops such as soybeans and peanuts, Brevibacillus laterosporus can significantly increase the number of effective root nodules and boost the activity of nitrogenase within these nodules, thereby enhancing biological nitrogen fixation.
2. Biocontrol and Disease Suppression
This is one of the most widely studied functions of Brevibacillus laterosporus, which suppresses pathogenic bacteria through the production of various antimicrobial substances:
- Broad-spectrum antimicrobial activity: Research indicates that it exerts significant inhibitory effects against a wide range of plant pathogens. For instance, a specific strain designated X10 demonstrated an 81.8% control efficacy against tomato bacterial wilt in greenhouse pot trials, with field efficacy ranging between 58% and 68%.（1）
- Production of various antimicrobial peptides: This bacterium produces a variety of antimicrobial proteins and peptides (such as brevilaterins). Their bactericidal mechanism primarily involves binding to the cell membranes of pathogens—thereby altering membrane permeability—or interfering with critical metabolic pathways, such as ATP synthesis and peptidoglycan synthesis, ultimately leading to the death of the pathogens.
3. Applications in Animal Production
Recent research has expanded the application of Bacillus pumilus from crop cultivation to livestock and poultry farming, demonstrating its immense potential as a feed additive:
- Improved Meat Quality: Supplementing the feed of fattening pigs with Bacillus pumilus strain BL1 upregulates the expression of genes associated with oxidative muscle fibers. This improves the amino acid and fatty acid profiles of the pork, thereby enhancing overall meat quality. Interestingly, studies have found that heat-inactivated bacterial cells are even more effective than live bacteria in improving meat quality.
- Regulation of Gut Health: By modulating the balance of the intestinal microecology, B. pumilus inhibits the growth of pathogenic bacteria and boosts the animal’s systemic immunity, thereby reducing the need for antibiotics.
- Excellent Tolerance: As a feed additive, this bacterium exhibits excellent heat resistance (maintaining an 86.2% survival rate after a 5-minute water bath at 85°C) and can withstand gastric acids and bile salts, ensuring that it remains functionally active throughout processing and its passage through the digestive tract.
4. Environmental Adaptability and Safety
- Environmental Stability: The antimicrobial proteins produced by Bacillus pumilus demonstrate broad pH stability (pH 5.0–11.0) and excellent thermal stability (withstanding temperatures up to 90°C), facilitating the preservation and application of formulations containing the organism.
- Biosafety: Studies have confirmed that certain superior strains (e.g., S62-9) exhibit no resistance to common veterinary antibiotics and possess no transferable resistance genes, thereby ensuring a high level of biosafety.
Microorganisms with Functions Similar to Bacillus pumilus
In agricultural production, numerous microorganisms share functions similar or complementary to those of Bacillus pumilus; these are often used in combination to achieve synergistic effects. The following are several typical examples:
| Microorganism Name | Primary Similar Functions | Unique Advantages and Application Distinctions |
| Bacillus subtilis | Disease prevention, growth promotion | The most widely applied species; considered the “benchmark” strain for microbial inoculants. It focuses on enhancing plant systemic resistance and inducing the plant’s own innate immunity. |
| Bacillus amyloliquefaciens | Disease prevention, growth promotion | Possesses a broad spectrum of disease-preventive activity, demonstrating particularly outstanding efficacy against fungal plant diseases. In patented formulations, it is frequently combined with Brevibacillus laterosporus to jointly promote nodulation and yield increases in leguminous crops. |
| Bacillus mucilaginosus | Phosphorus Solubilization, Potassium Solubilization, Growth Promotion | Its most distinctive feature is its potassium-solubilizing capability; it can release mineral potassium that has become fixed within the soil. This function perfectly complements the phosphorus-solubilizing activity of Brevibacillus laterosporus, and together, they provide comprehensive nutritional support to crops. |
| Paenibacillus polymyxa | Root System Promotion | Similar to Brevibacillus laterosporus, it can significantly promote the elongation of primary roots —as well as increase the number of lateral roots —in crops such as peas and soybeans, thereby playing a prominent role in fostering root system development. |
| Streptomyces spp. | Disease Prevention, Growth Promotion | Its primary mechanism for disease prevention involves the production of various antibiotics to inhibit the growth of pathogenic bacteria; concurrently, it secretes auxins to stimulate root growth. |
In practical applications, formulating a microbial consortium by combining Brevibacillus laterosporus with one or more of the aforementioned microorganisms typically yields results that are more comprehensive and stable than those achieved using a single microbial strain alone. For instance, existing patented technologies have successfully combined Bacillus amyloliquefaciens, Brevibacillus laterosporus, and Bacillus mucilaginosus to significantly increase both the number of root nodules and the nitrogenase activity in leguminous crops such as peanuts and soybeans.