Lactobacillus plantarum in Agriculture: A Natural Ally for Healthier and Stronger Plants

Beneficial microorganisms are becoming increasingly important in agriculture as growers look for ways to improve plant establishment, nutrient efficiency and crop resilience. One microorganism receiving growing scientific interest is Lactobacillus plantarum, a versatile lactic acid bacterium commonly associated with plants, fermented foods, silage and other organic materials.

The currently accepted scientific name is Lactiplantibacillus plantarum. The species was transferred from the former broad genus Lactobacillus during a major taxonomic reclassification in 2020. However, the former name, Lactobacillus plantarum, remains widely used in agriculture, product literature and online searches. The updated name is confirmed by the List of Prokaryotic Names with Standing in Nomenclature.

Selected strains of L. plantarum have demonstrated promising plant growth-promoting, fermentation and antagonistic properties. However, these functions are strain-specific. Evidence obtained with one strain cannot automatically be applied to every L. plantarum culture or commercial product.

What Is Lactobacillus plantarum?

Lactiplantibacillus plantarum is a Gram-positive, non-spore-forming lactic acid bacterium. It can use a wide range of plant-derived carbohydrates and convert them into lactic acid and other metabolites. This metabolic flexibility allows it to survive in diverse environments, including:

• Plant surfaces

• The rhizosphere surrounding plant roots

• Fermented vegetables

• Silage and stored forage

• Composting or fermenting plant materials

• Food and feed fermentation systems

Unlike bacteria such as Azotobacter, Rhizobium or certain Azospirillum strains, L. plantarum is not primarily classified as a nitrogen-fixing bacterium. It should therefore not be presented as a direct replacement for nitrogen fertilizer.

Its agricultural value is instead associated with fermentation, organic-acid production, root colonization by selected strains, plant-associated metabolites and competition with certain undesirable microorganisms.

Benefits and Applications of Lactobacillus plantarum

The agricultural applications of L. plantarum range from well-established silage fermentation to emerging uses as a plant-associated microbial inoculant.

Agricultural application	Potential function	Current evidence status
Silage inoculation	Rapid acidification and improved forage preservation	Well established for appropriately selected silage strains
Seed and seedling treatment	Support for germination, root development and early growth	Promising controlled-environment evidence
Root-zone application	Rhizosphere colonization and production of plant-associated metabolites	Emerging and strongly strain-dependent
Abiotic-stress management	Possible support under drought, heat or salinity stress	Mainly laboratory, pot and greenhouse evidence
Biological disease management	Competition, acidification and antimicrobial metabolite production	Supported for selected strains and pathogens; registration may be required
Organic-material fermentation	Controlled acidification of plant residues and organic substrates	Process- and formulation-dependent
Postharvest biopreservation	Restriction of selected spoilage and pathogenic microorganisms	Supported for particular strains and commodities

1. Silage and forage preservation

Silage fermentation is one of the best-established agricultural uses of lactic acid bacteria. Selected L. plantarum strains are applied to freshly harvested forage to encourage rapid lactic acid production under anaerobic conditions.

As lactic acid accumulates, the pH of the forage declines. This helps restrict undesirable microorganisms and supports the preservation of dry matter and nutritional quality. Results still vary with the bacterial strain, forage crop, moisture level, sugar availability, packing density and storage conditions.

A large meta-analysis of lactic acid bacterial silage inoculants found that responses differed among forage types. This demonstrates why a strain developed for silage cannot automatically be assumed to promote roots when applied to soil.

2. Seed germination and seedling establishment

Selected strains of L. plantarum have been investigated as seed or seedling inoculants. Potential benefits reported under experimental conditions include:

• Improved germination

• Greater seedling vigour

• Increased primary or lateral root development

• Higher root and shoot biomass

• Better early plant establishment

For example, a controlled study of tomato seedlings reported improved germination and seedling growth following treatment with particular L. plantarum strains. The response depended on strain and treatment conditions rather than simply the presence of the species. The study is available through Acta Physiologiae Plantarum.

These findings support further development of strain-specific seed treatments, but they do not establish a universal seed-treatment rate for every L. plantarum product.

3. Rhizosphere colonization

For a microbial root inoculant to remain active, it must survive application and interact successfully with the root-zone environment. Some L. plantarum strains appear better adapted to plant-associated habitats than strains isolated for food or probiotic applications.

A 2025 controlled pot study examined L. plantarum strain LP0308, originally isolated from tomato rhizosphere soil. The strain colonized the tomato root zone and was associated with increases in root length, plant height, seedling biomass and root indole-3-acetic acid concentration. Because the experiment used sterilized soil and young potted plants, the findings should be viewed as promising controlled-environment evidence rather than proof of consistent field performance. The full study is published in Frontiers in Microbiology.

What Is the Use of Lactobacillus in Agriculture?

The former genus Lactobacillus included a very large and biologically diverse group of lactic acid bacteria. Following taxonomic reclassification, many of these species now belong to newly named genera. Therefore, “Lactobacillus” should not be treated as one organism with a single agricultural function.

Depending on the exact species and strain, lactic acid bacteria may be used for:

• Silage and forage fermentation

• Fermented animal-feed production

• Seed or root-zone microbial inoculation

• Fermentation of plant-based organic materials

• Postharvest biopreservation

• Experimental management of plant pathogens

• Support of plant responses to environmental stress

Among these organisms, L. plantarum is especially interesting because of its association with plants and its capacity to produce organic acids and other biologically active compounds.

Fermentation of agricultural materials

During fermentation, L. plantarum converts soluble plant sugars into organic acids, particularly lactic acid. This controlled acidification can help stabilize silage and certain fermented organic materials.

In composting, however, L. plantarum should be understood as a fermentation-stage microorganism rather than a complete composting solution. Mature aerobic composting requires a succession of bacteria, fungi and other decomposers. Excessive acidification or the inappropriate addition of wet fermentates can interfere with normal compost aeration and decomposition.

Plant-associated microbial products

When included in a well-designed microbial formulation, an agriculturally selected L. plantarum strain may be applied to seeds, seedlings, transplant roots or the rhizosphere. Its ability to perform after application depends on viable-cell concentration, formulation stability, carrier, storage, crop, soil conditions and competition from the existing microbiome.

Biological crop protection research

Selected L. plantarum strains produce lactic acid, phenyllactic acid, bacteriocins known as plantaricins, cyclic peptides and other metabolites capable of restricting particular microorganisms under laboratory conditions.

Strains PC40, PM411, TC54 and TC92, for example, were investigated against Erwinia amylovora, the bacterium responsible for fire blight in apples and pears. Certain strains colonized blossoms and reduced infection in controlled and semi-field experiments. This evidence applies to the tested strains, crop tissues and pathogen system. It does not mean that every L. plantarum culture controls fire blight or other plant diseases. The research is available in the European Journal of Plant Pathology.

Any commercial claim involving disease control may require the product to be evaluated and registered as a microbial biopesticide in the intended market.

How Lactobacillus plantarum May Improve Plant Growth

Selected L. plantarum strains may support plant performance through several direct and indirect mechanisms.

Production of plant-associated metabolites

Some strains produce or influence compounds associated with plant development, including indole-3-acetic acid and certain gibberellin-related metabolites. Auxin-related activity can affect root elongation, lateral-root formation and root architecture.

These effects are concentration-sensitive. An amount that supports root development under one set of conditions may produce no benefit under another. Consequently, metabolite production observed in laboratory culture is not enough to guarantee growth promotion in soil.

Organic-acid production

Lactic, acetic and other organic acids can change conditions around microbial cells. In laboratory tests, acid production by selected strains has been associated with the solubilization of some mineral phosphates.

Agricultural soils are strongly buffered, however, and contain complex mineral and organic components. An in-vitro phosphate-solubilization zone should therefore be described as a microbial capability, not as proof that a product will supply a predictable quantity of phosphorus to a crop.

Root-zone colonization and biofilm formation

Certain plant-associated strains can adhere to root surfaces and form biofilms. Successful colonization may allow the bacteria to remain near root exudates and interact with the developing plant for longer.

This property varies significantly among strains. A food-fermentation or human-probiotic strain may not have the same root-colonization ability as a strain isolated from the rhizosphere.

Competition with undesirable microorganisms

A strain that colonizes the same habitat as another microorganism may compete for nutrients and attachment sites. Organic acids and antimicrobial metabolites may provide additional antagonistic activity.

Most published evidence in this area remains pathogen-, crop- and strain-specific. A recent review in Frontiers in Plant Science concluded that evidence connecting laboratory antagonism with reliable field control remains limited.

Support under environmental stress

Research has also examined whether certain lactic acid bacteria can help plants maintain physiological activity during drought, heat or salinity stress. Proposed responses include changes in antioxidant enzyme activity, photosynthetic pigments and root development.

A 2024 pot study found that an experimental L. plantarum isolate influenced wheat germination and physiological responses under drought and heat treatments. These results are encouraging, but further field trials are required before drought or heat tolerance can be treated as a dependable commercial outcome. The study can be reviewed in the Journal of King Saud University – Science.

Different Strains of Lactobacillus plantarum

A strain is a genetically distinct population within a microbial species. Two organisms can both be identified as L. plantarum while differing substantially in their metabolism, stress tolerance, root colonization and antimicrobial activity.

Research examples include:

Strain or strain group	Research application	Evidence boundary
LP0308	Tomato rhizosphere colonization and seedling growth	Controlled pot and sterilized-soil evidence
ONU 12, ONU 311 and ONU 355	Wheat germination, root development and biofilm formation	Experimental hydroponic and soil studies
PM411, TC54, TC92 and PC40	Antagonism toward fire-blight bacteria on apple and pear tissues	Controlled and semi-field crop-protection research
MiLAB 393	Production of phenyllactic acid and antifungal cyclic compounds	Primarily biochemical and laboratory evidence
Commercial silage strains	Acidification and preservation of ensiled forage	Performance depends on forage, formulation and ensiling conditions
Food or probiotic strains	Food fermentation or human and animal probiotic research	Agricultural plant benefits cannot be assumed

Genomic and phenotypic research has confirmed considerable diversity among plant-associated L. plantarum isolates. This reinforces the importance of identifying agricultural cultures by strain rather than only by species. Further information is available in the study on strain diversity of plant-associated L. plantarum.

When assessing a microbial product, growers should look for:

• Full strain identification

• Declared viable-cell concentration

• Formulation and carrier information

• Storage requirements and shelf life

• Supported crops and application routes

• Crop-specific greenhouse or field trials

• Local regulatory authorization

How to Use Lactobacillus in the Garden

Gardeners should use a commercially prepared microbial inoculant intended for horticultural application rather than attempting to reproduce a research treatment or prepare an unverified homemade culture.

Root-zone application

If the product label permits root application, dilute or disperse it according to the manufacturer’s instructions and apply it to the moist root zone. This may be suitable for:

• Vegetable beds

• Container plants

• Transplants

• Ornamentals

• Young fruit plants

• Greenhouse crops

The objective is to bring viable cells into contact with the developing roots. Applying the product only to dry soil far from the root zone is unlikely to provide the same opportunity for colonization.

Seed and seedling treatment

Only use L. plantarum as a seed treatment when the formulation is specifically designed and labelled for that purpose. Seed-coating performance depends on the strain, viable count, coating material, drying conditions and the length of time between treatment and sowing.

For seedlings, label-approved inoculants may be delivered through nursery media, plug trays, transplant water or a root dip.

Compost and organic-material fermentation

A fermentation inoculant can be applied to appropriate plant residues according to its instructions. It should not replace the carbon-to-nitrogen balance, moisture control, aeration and turning required for effective aerobic composting.

Foliar application

Foliar use should be limited to products developed and authorized for leaf application. A strain that performs well as a silage organism or root-zone inoculant may not survive ultraviolet exposure, desiccation and fluctuating humidity on leaf surfaces.

Avoid unverified homemade cultures

Recipes based on milk, rice-wash water or uncontrolled plant fermentation do not provide reliable strain identity, purity or CFU concentration. A sour smell or low pH does not confirm the presence of L. plantarum, nor does it confirm the absence of undesirable microorganisms.

Check input compatibility

Do not assume that living bacterial inoculants are compatible in the same tank with disinfectants, bactericidal products, oxidizing agents or strongly acidic or alkaline inputs. Compatibility must be confirmed for the exact formulation. Where evidence is unavailable, apply products separately according to their labels.

For professional evaluation, include a small untreated control area and record germination, plant height, root development, crop quality and any signs of phytotoxicity.

Limitations and Practical Considerations

The agricultural potential of L. plantarum is real but should not be overstated. Its performance can be affected by:

• Strain identity

• Viable-cell concentration

• Formulation quality

• Storage conditions

• Application timing

• Soil moisture and temperature

• Crop and cultivar

• Existing rhizosphere microorganisms

• Organic-matter availability

• Compatibility with fertilizers and crop-protection inputs

The species is considered suitable for the Qualified Presumption of Safety approach in certain European food and feed assessments. However, this does not automatically authorize every strain or formulation for agricultural use. Safety, efficacy and regulatory status must be evaluated for the strain, product and intended application.

Conclusion

Lactiplantibacillus plantarum, still widely known as Lactobacillus plantarum, is a versatile plant-associated lactic acid bacterium with established value in silage fermentation and promising applications in plant biostimulation, seedling establishment, root-zone management and biological crop-protection research.

Selected strains may influence root development, organic-acid production, plant-associated metabolites, rhizosphere colonization and stress responses. These benefits are not universal across the species. Reliable agricultural performance requires a carefully selected strain, stable formulation, appropriate viable count, correct application route and validation in the target crop and environment.

For additional technical information, visit the IndoGulf BioAg Lactobacillus plantarum microbial species page.

Technical disclaimer: This article summarizes species- and strain-level scientific research. It does not establish the performance, application rate, compatibility, regulatory status or disease-control efficacy of any specific commercial product. Always follow the locally approved label and applicable agricultural regulations.