The Role of Paenibacillus mucilaginosus in Agriculture
Paenibacillus mucilaginosus (also known as Paenibacillus gelatins) is one of the most widely utilized functional microorganisms in microbial fertilizers. Its core functions can be summarized as activating soil nutrients, promoting nutrient uptake by crops, and enhancing stress resistance.
1. Activating Soil Potassium—Its Primary Function
The most prominent function of Paenibacillus mucilaginosus is potassium solubilization. It secretes organic acids (such as oxalic acid, tartaric acid, citric acid, etc.) and extracellular polysaccharides, breaking down insoluble aluminosilicate minerals in the soil (such as mica and feldspar). This process releases potassium ions—which were previously fixed within the minerals—into a form of readily available potassium that can be absorbed by crops.
Research data indicates that following co-inoculation with Paenibacillus mucilaginosus and Pseudomonas fluorescens, the content of soluble potassium in the soil increased by 21.6%–33.6%, while exchangeable potassium content rose by 15.7%–22.6%. （1）Field trials involving soybeans have further confirmed that inoculation with Paenibacillus mucilaginosus results in an 8.5% increase in readily available soil potassium content at the crop’s maturity stage compared to control groups.（2）
2. Possessing Both Phosphorus Solubilization and Nitrogen Fixation Capabilities
In addition to solubilizing potassium, Paenibacillus mucilaginosus also possesses capabilities for phosphorus solubilization and nitrogen fixation. It converts insoluble phosphorus in the soil into available phosphorus for crop uptake, while simultaneously fixing free nitrogen from the atmosphere. This renders it particularly valuable for application in nutrient-poor or barren soils.
3. Promoting Crop Growth and Increasing Yields
By activating nutrients, Paenibacillus mucilaginosus significantly promotes crop growth and development. Field trials have demonstrated the following results:
Soybeans: Following inoculation, the grain weight per plant increased by 12.8%, and the overall yield rose by 9.3%.（2）
Zucchini: Following co-inoculation with Paenibacillus mucilaginosus and Pseudomonas fluorescens, both the plant dry weight and total yield showed significant increases.（1）
4. Enhancing Crop Stress Resistance
Paenibacillus mucilaginosus facilitates the breakdown of silicon elements in the soil, making them available for plant utilization. This leads to a thickening of the waxy layer on the plant’s epidermal cells, thereby enhancing both water retention capacity and disease resistance. Additionally, it secretes various enzymes, thereby enhancing crops’ resistance to diseases.
5. Improving the Soil Micro-ecological Environment
The application of Bacillus mucilaginosus enriches the diversity of the soil microbial community, increases the populations of bacteria and actinomycetes, and inhibits fungal growth. This facilitates the transition of the soil ecosystem from a “fungal-dominant” type to a beneficial, “bacterial-dominant” type.
Bacterial Strains with Functions Similar to Paenibacillus mucilaginosus
The following bacterial strains share functional similarities with Bacillus mucilaginosus. In particular, they can serve as complements or substitutes in areas such as potassium solubilization, phosphorus solubilization, and growth promotion:
| Strain Name | Core Functions | Similarities and Differences vs. Bacillus mucilaginosus |
| Paenibacillus mucilaginosus | Solubilizes potassium; releases macro- and micro-elements | Essentially the same type of bacterium (an earlier name for Bacillus mucilaginosus); functions are fundamentally identical. |
| Bacillus megaterium | Solubilizes phosphorus (organic phosphorus) | Focuses on phosphorus solubilization rather than potassium; complements Paenibacillus mucilaginosus. |
| Pseudomonas fluorescens | Solubilizes potassium; secretes siderophores; produces plant hormones | Also possesses silicate-solubilizing capabilities; exhibits synergistic effects when combined with Paenibacillus mucilaginosus. |
| Pseudomonas marginalis | Solubilizes potassium; promotes growth | A novel potassium-solubilizing bacterium; research in 2025 confirmed its significant growth-promoting effects on maize. |
| Rhodopseudomonas palustris | Solubilizes potassium; fixes nitrogen; produces growth-promoting substances | A representative potassium-solubilizing photosynthetic bacterium; can simultaneously reduce the required dosage of potassium fertilizers. |
| Bradyrhizobium japonicum | Symbiotic nitrogen fixation | Complementary functions—one fixes nitrogen while the other solubilizes potassium; combined inoculation yields superior results compared to single-strain application. |
| Bacillus subtilis | Stress tolerance; nitrogen fixation | Possesses stronger disease-resistance capabilities, but its nutrient-activation capacity is inferior to that of Paenibacillus mucilaginosus. |
| Brevibacillus laterosporus | Promotes root growth; acts as a biocide; degrades heavy metals | Focuses more on disease prevention and direct growth promotion; its nutrient-activation capacity is relatively weak. |
A closer look at several similar “potassium-solubilizing” functional bacteria:
(1) Pseudomonas fluorescens
This represents another category of potassium-solubilizing bacteria that has been extensively researched. It exhibits no antagonistic effects toward Bacillus mucilaginosus and can be used in combination with it. The synergistic mechanism between the two lies in their ability to secrete different types of organic acids, thereby jointly accelerating mineral weathering and releasing potassium. Studies indicate that following their co-inoculation, both zucchini yield and potassium uptake levels surpass those achieved through single-strain inoculation.（3）
(2) Purple Non-sulfur Bacteria (PNSB)
Recent research has revealed that certain photosynthetic bacteria also possess potassium-solubilizing capabilities. A field trial published in 2025 demonstrated that—following inoculation with strains such as Rhodopseudomonas palustris—soil exchangeable potassium levels rose from 0.428 to 0.460–0.470 meq/100g, while maize yields increased from 11.1 to 12.2–12.6 tons/hectare. Furthermore, this approach allowed for a 100% reduction in chemical potassium fertilizer application without compromising crop yield.（4）
(3) Pseudomonas marginalis
A potassium-solubilizing bacterial strain, newly reported in 2025 and isolated from the maize rhizosphere, demonstrated a potassium solubilization capacity of 222.1 mg/L in mica-based culture media. Both greenhouse and field trials have confirmed its ability to significantly promote maize growth.（5）
Application Recommendations
1.For Single-Function Requirements, Choose Bacillus mucilaginosus: If the primary objective is to address issues such as soil potassium deficiency or low fertilizer utilization efficiency, Bacillus mucilaginosus represents a mature and reliable choice.
2.Combined Application Yields Superior Results: Combining Bacillus mucilaginosus with phosphorus-solubilizing bacteria (e.g., Bacillus megaterium) or nitrogen-fixing bacteria (e.g., Rhizobium) enables a synergistic, multi-functional effect encompassing potassium solubilization, phosphorus solubilization, and nitrogen fixation.
3.Use in Conjunction with Reduced Chemical Fertilizers: Microbial inoculants cannot completely replace chemical fertilizers; however, they can be utilized in combination with reduced doses of chemical fertilizers to enhance nutrient utilization efficiency while simultaneously protecting soil health.
4.Verify Strain Compatibility: Prior to combined application, it is essential to verify that no antagonistic interactions exist between the different bacterial strains to ensure the efficacy of the treatment.