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Sigma Bio · science visuals

The living science beneathevery Sigma fertilizer.

Sigma Bio is a consortium of beneficial Bacillus bacteria, Trichoderma fungi and arbuscular mycorrhizal fungi. It is applied on its own as a liquid and built into every Sigma dry fertilizer. Watch what it does in the root zone, then go deeper, figure by figure.

Film · Sigma Bio Science · 2 min 23 sScientific illustration · sound on

What's in Sigma Bio

Three groups of organisms, one working root zone

Each organism has a job. Together they colonize the root, build soil structure, release locked nutrients and help turf through seasonal stress.

Bacteria

Bacillus team

Bacillus subtilis
Bacillus amyloliquefaciens
Bacillus licheniformis
Brevibacillus laterosporus

Root colonization, plant growth hormones, stress relief, phosphate release and cool-soil activity.

Beneficial fungi

Trichoderma

Trichoderma harzianum
Trichoderma viride

Root cortex colonization, organic acids and phosphatase enzymes.

Symbiotic fungi

Endomycorrhizae

Glomus intraradices
Glomus etunicatum
Glomus aggregatum
Glomus mosseae

Nutrient exchange inside the root, an extended hyphal network and glomalin soil structure.

On its own: Sigma Bio liquid, tank-mixed into your spray programBuilt in: carried in every Sigma dry fertilizer

Inside the root zone

Fifteen figures, six chapters

The rootzone

Where turf lives, and where Sigma Bio goes to work.

What you're looking atA USGA-style putting green profile: turf and thatch over a 10 to 12 inch sand rootzone, gravel layer and drainage, with the root and soil interface magnified.

Overcoming agronomic challenges in sand-based rootzones

High-sand USGA putting green profiles offer exceptional compaction resistance and drainage, but they present real biological and nutrient management hurdles.

Washed sand is inert and has a very low cation exchange capacity (CEC). Soluble fertilizer moves quickly below the rootzone, and native microbial populations struggle to establish.

Building a functional soil food web in a high-sand matrix takes targeted biological inoculation: biology that builds organic CEC, improves moisture retention and drives continuous nutrient cycling beneath the turf canopy.

Cation exchange capacity
Leaching
Soil food web

What you're looking atA turfgrass root pushing down through sand grains, its surface covered in fine root hairs.

Expanding the absorptive surface area of turfgrass roots

The rhizosphere, the narrow zone of soil directly influenced by root secretions, is the engine of plant nutrition and stress tolerance. Healthy turfgrass roots release carbon-rich exudates (sugars, amino acids and organic acids) that recruit beneficial soil microorganisms.

As roots extend, microscopic root hairs multiply and greatly increase the surface area available for water and nutrient uptake.

Inoculating the rootzone means new root hairs are colonized by beneficial microbes as they form, so the most valuable real estate in the soil is occupied by the right organisms first.

Rhizosphere
Root exudates
Root hairs

Colonization

From dormant spore to a living shield on the root.

What you're looking atSigma Bio endospores, the dormant golden-brown capsules, suspended in soil water among mineral particles.

Rapid microbial colonization through endospore activation

Sigma Bio's Bacillus species are applied as dormant, highly stable endospores that survive tank mixing and variable soil conditions.

When they meet root exudates, warmth and soil moisture, the spores germinate into active vegetative cells within hours. The bacteria then multiply by binary fission, dividing again and again to populate the root surface, with active colonization in about three days.

This fast start builds dominant beneficial populations that claim root space and carbon resources ahead of competing soil organisms: the principle of competitive exclusion.

Endospore
Germination
Binary fission
Competitive exclusion

What you're looking atBeneficial bacteria bound together in a biofilm matrix spread across the root surface.

Protective micro-shielding and rhizoplane biofilm formation

Once established on the rhizoplane (the root surface itself), beneficial bacteria secrete extracellular polymeric substances (EPS) that build a protective matrix called a biofilm.

The biofilm anchors the microbial community to the root, so it is not washed away by heavy irrigation or rainfall.

It also works as a selective barrier: it holds moisture around delicate root tissue during drought and concentrates microbial enzyme activity right where the root can use what it releases.

Rhizoplane
Extracellular polymeric substances
Biofilm

The mycorrhizal network

A second root system, built by fungi.

What you're looking atInside a single root cortex cell: a tree-like arbuscule branching through the cell, with mineral nutrients (blue) and plant carbon (amber) changing hands.

Direct intracellular nutrient and carbohydrate exchange

Arbuscular mycorrhizal fungi (Sigma Bio carries four Glomus species) form an obligate symbiosis with turfgrass roots. They grow into the root cortex and build intricate, highly branched structures called arbuscules inside the cells, without breaking the host cell membrane, which folds around them.

Each arbuscule is a two-way exchange hub. The plant supplies the fungus with photosynthetic carbon (sugars and lipids). The fungus delivers mineral nutrients, chiefly phosphorus and zinc, which move poorly through soil on their own.

Those nutrients pass across the membrane into the root cells and move on through the plant.

Arbuscule
Root cortex
Obligate symbiosis

What you're looking atA sand profile cut open: grass roots above, and a fine white web of fungal hyphae reaching well past them into the pore space.

Extending soil exploration beyond the root zone

Root hairs reach only fractions of a millimeter into the soil around them. Mycorrhizal hyphae are far finer and reach much farther, branching through the soil matrix for several centimeters beyond the root and growing up to about 3 mm a day.

This extraradical network enters micropores too small for any root, multiplies the volume of soil the plant can draw from, and opens nutrient reserves the turf could never reach on its own.

Extraradical hyphae
Micropores
Absorptive volume

What you're looking atMagnified sand grains held together by fungal hyphae and an iridescent glomalin matrix, forming stable aggregates with open pore space between them.

Building durable soil structure in high-sand profiles

As mycorrhizal hyphae work through the soil, they deposit glomalin, a durable, water-resistant glycoprotein that acts as a natural biological glue.

In a high-sand rootzone, glomalin binds loose sand grains and mineral particles into stable aggregates.

That structure improves water-holding capacity and aeration and lowers bulk density, while the large pores that carry drainage stay open.

Glomalin
Aggregation
Bulk density

The Bacillus team

Four specialists, four jobs in the root zone.

What you're looking atBacillus subtilis cells colonizing a turfgrass root and multiplying along its surface.

Bacillus subtilis: root colonization and hormone-driven root growth

Bacillus subtilis is a premier root-colonizing bacterium. It forms a robust biofilm across young root tissue and occupies the root surface ahead of competing organisms.

It also produces natural plant hormones, notably indole-3-acetic acid (IAA), an auxin. Auxin stimulates cell division and elongation at the root tip, driving deeper roots, more lateral branching and greater total root mass.

Auxin (IAA)
Root elongation
Lateral roots

What you're looking atBacillus amyloliquefaciens on a root, releasing the enzyme ACC deaminase (violet) into the root zone.

Bacillus amyloliquefaciens: easing summer heat and drought stress

Under extreme heat, salinity or drought, turfgrass produces excess ethylene, a stress hormone that triggers early root decline and canopy thinning.

Bacillus amyloliquefaciens produces the enzyme ACC deaminase, which breaks down ACC, the plant's direct precursor to ethylene, into ammonia and alpha-ketobutyrate.

With less ACC available, the plant makes less stress ethylene, and roots hold on through hard summer conditions.

Ethylene
ACC deaminase
Root senescence

What you're looking atBacillus licheniformis (violet) working on a piece of insoluble calcium phosphate, releasing plant-available phosphate (green) into the soil.

Bacillus licheniformis: unlocking bound calcium and iron phosphates

In high-pH or calcareous sand rootzones, applied phosphorus quickly binds with calcium, iron or aluminum into insoluble minerals that roots cannot absorb.

Bacillus licheniformis releases low-molecular-weight organic acids, such as gluconic and citric acid, along with phytase enzymes.

These compounds chelate the binding metals and dissolve locked mineral phosphate, releasing plant-available orthophosphate (HPO₄²⁻ and H₂PO₄⁻) right in the root zone.

Phosphate solubilization
Organic acids
Phytase

What you're looking atBrevibacillus laterosporus (blue) active along a root in cold, frost-flecked soil.

Brevibacillus laterosporus: biological activity in early spring and late fall

Many beneficial soil microbes slow down sharply as soils cool in spring and fall.

Brevibacillus laterosporus is adapted to keep working in cool soils, continuing to produce enzymes when other populations go quiet.

That cool-season activity supports earlier spring green-up, faster recovery after winter, and continued root development while soil temperatures stay low.

Cool-soil activity
Hydrolytic enzymes
Spring green-up

The Trichoderma team

Beneficial fungi that work the root cortex.

What you're looking atTrichoderma harzianum hyphae (green) weaving along the outer root, releasing organic acids (gold).

Trichoderma harzianum: organic acids and a primed plant

Trichoderma harzianum is a vigorous fungal root colonizer that grows along the outer root cortex.

It secretes organic acids (citric, fumaric and gluconic) that lower pH right at the root surface and dissolve micronutrients into usable forms.

Its presence on the root also triggers induced systemic resistance (ISR), priming the turfgrass plant's own stress-response pathways so it responds faster when stress arrives.

Root cortex
Organic acids
Induced systemic resistance

What you're looking atTrichoderma viride hyphae releasing phosphatase enzymes (emerald) that free bound phosphorus from soil particles beside a root hair.

Trichoderma viride: phosphatase activity and fertilizer efficiency

Trichoderma viride produces high levels of acid and alkaline phosphatase enzymes. These cleave organically bound phosphate in the soil's organic fraction and convert it to inorganic forms the plant can take up.

Combined with a larger, more active root system, that raises phosphorus use efficiency, so turf managers get more from every pound of phosphorus they apply.

Phosphatase
Organic phosphorus
Nutrient use efficiency

From tank to green

How the biology gets there, and what it looks like from above.

What you're looking atGolden-brown Bacillus endospores suspended in a liquid spray tank mix.

Tank-mix stability and endospore survival

Fragile vegetative bacteria break down quickly in a spray tank. Sigma Bio's Bacillus strains are delivered as endospores: thick-walled, dormant capsules wrapped in a multilayered protein coat.

That shell protects the cell through high-shear spray pumps, UV light, osmotic pressure and tank partners, including fertilizers, fungicides, insecticides, PGRs and wetting agents.

After application the spores wash down into the thatch and soil and stay viable until moisture and root exudates signal them to germinate.

Endospore coat
Tank mix
Viability

What you're looking atA putting green cut in cross-section: dense turf, a 12 inch USGA sand rootzone full of deep white roots, pea gravel and drainage.

Canopy health starts below ground

Putting greens take intense daily stress: very low mowing heights, foot traffic, heat and humidity. A dense, uniform canopy is direct evidence of a healthy rootzone.

By establishing active biology in the root zone, Sigma Bio improves water infiltration, increases nutrient uptake efficiency and helps turf hold up through heat and drought, so turf managers keep tournament-quality playability with fewer inputs.

Rootzone health
Water infiltration
Playability

Where you'll find it

The same biology, two ways to apply it

Liquid

Sigma Bio

The full consortium in a dormant suspension that goes into the tank with your fungicides, insecticides, PGRs, wetting agents and fertilizers.

Open the technical data sheet → Granular

Every Sigma dry fertilizer

The same organisms, carried on Sigma granulars with humate, so every feeding also inoculates the root zone.

See the product line →

Go deeper

The evidencePublished field research behind each organism Strain of the weekThe organisms in Sigma Bio, one at a time GlossaryEvery term on this page, in plain language Sigma Bio technical briefPDF · the science in print

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Figures are scientific illustrations based on published soil microbiology; organisms and structures are enlarged and simplified for clarity. Sigma products are not pesticides. Always read and follow the product label.