Description:FIELD OF THE INVENTION
The invention relates to a root-responsive biodegradable capsule composition for targeted bioagent delivery in agriculture. The composition employs root-responsive and soil-triggered mechanisms to release microbial agents in a controlled manner, enhancing bioagent survival, targeted colonization, and sustainable management of soilborne pathogens.
BACKGROUND OF THE INVENTION
Several pathogens cause considerable damage to the crops, out of which soilborne pathogens have significant impact on crop loss. For the management of these soilborne pathogens bioagents are the viable options which are environment friendly. But the current application methods like broadcasting and the soil drenching leads to the mortality of the bioagents after their application. There’s a critical gap in bioagent delivery systems that can respond to rhizosphere-specific triggers like moisture or root exudates.
US9447462B2: The present invention provides methods for the quantification of an unknown bioagent in a sample by amplification of nucleic acid of the bioagent, and concurrent amplification of a known quantity of a calibration polynucleotide from which are obtained a bioagent identifying amplicon and a calibration amplicon. Upon molecular mass analysis, mass and abundance data are obtained. The identity of the bioagent is then determined from the molecular mass of the bioagent identifying amplicon and the quantity of the identified bioagent in the sample is determined from the abundance data of the bioagent identifying amplicon and the abundance data of the calibration amplicon.
US8815513B2: The present invention provides methods for rapid forensic investigations by identification of bioagents associated with biowarfare and acts of terrorism or crime. The methods are also useful for epidemiological investigations by genotyping of bioagents.
Current methods of applying bioagents, such as broadcasting, soil drenching, and seed treatments, suffer from poor survival rates, random distribution, and unsynchronized activation of microbes. These approaches often require excessive quantities, leading to wastage, uneven colonization, and reduced efficiency in disease suppression. Additionally, bioagents applied directly are vulnerable to environmental stresses such as desiccation, ultraviolet exposure, or antagonism by soil microbes.
The present invention solves these problems by developing a root-responsive biodegradable capsule that protects and delivers bioagents directly to the root zone. The capsule activates only under specific rhizosphere conditions such as root exudates, soil moisture, or pathogen-secreted enzymes. This ensures targeted colonization, extended survival, minimized wastage of inputs, and reduced reliance on chemical fungicides.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention.
This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
The invention provides a smart capsule system designed for the precise and eco-friendly delivery of bioagents. The capsule consists of a biodegradable shell formulated with materials such as alginate or chitosan, which degrade in response to rhizosphere-specific triggers. The core of the capsule contains bioagents such as beneficial fungi or bacteria, optionally supplemented with micronutrients or plant defense inducers to enhance plant growth and immunity.
Once applied to the soil, the capsules remain dormant until they encounter root-specific stimuli such as moisture gradients, sugars, or pathogen enzymes. Upon activation, the capsule releases the encapsulated bioagents in a controlled manner at the root surface, enabling effective colonization and targeted suppression of soilborne pathogens.
This system improves bioagent efficiency, reduces losses due to environmental factors, and promotes sustainable farming practices. By synchronizing release with crop development stages and soil biology, it ensures precision delivery, enhances crop health, and minimizes input costs.
The biodegradable nature of the capsule ensures no harmful residues remain in the soil, making the technology farmer-friendly, eco-friendly, and scalable for diverse agricultural applications.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.
DETAILED DESCRIPTION OF THE INVENTION
The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
In addition, the descriptions of "first", "second", “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The proposed invention “a Root-Responsive Biodegradable Capsule System” addresses the limitations of existing bioagent delivery methods by enabling targeted, trigger-based activation of beneficial microbes directly in the rhizosphere.
1. Targeted Activation: After the application the capsule remains inactive in the bulk soil and activates only when it comes in contact with specific rhizosphere signals such as:
• Moisture levels typical of root zones,
• Root exudates (e.g., amino acids, sugars),
• Pathogen-secreted enzymes (e.g., cellulases, pectinases).
2. Enhanced Survival and Colonization: As the application focused at the root zone, the formulation protects bioagents from early mortality due to UV exposure, desiccation, or antagonistic soil microbes. This increases root colonization efficiency and more consistent biocontrol activity.
3. Resource Efficiency: The resources can be applied effectively by the triggered mechanism which ensures small number of capsules for effective pathogen suppression, minimizing input waste and cost.
4. Eco-Friendly & Biodegradable: The capsule shell is made of biodegradable, plant-safe polymers (e.g., alginate, chitosan) that decompose naturally in soil without leaving residues.
Implementation Details:
1. Capsule Composition:
• Core contents:
o Bioagents such as Trichoderma sps, Pseudomonas fluorescens and Bacillus subtilis
o Optional additives: micronutrients (e.g., zinc, iron), plant defense inducers (e.g., salicylic acid)
• Coating material:
o Biodegradable polymer such as alginate, chitosan, or gelatin
o Incorporated with moisture- or enzyme-sensitive additives
2. Capsule Manufacturing:
• Wet encapsulation using drip or extrusion technique.
• Cross-linking in calcium chloride bath to form stable capsules.
• Capsules are dried to semi-soft state for better handling.
3. Application in Field:
• Capsules are either:
• Placed into transplant holes,
• Coated onto seeds,
• Broadcasted with compost at sowing.
• After application capsules remain inert until activated by rhizosphere conditions, triggering targeted release of viable microbes at root depth.
4. Outcome:
• Effective disease suppression of soilborne pathogens like Fusarium, Pythium, Rhizoctonia, Sclerotium.
• Stronger, more consistent root colonization by bioagents.
• Reduced dependence on chemical fungicides.
• Sustainable and scalable method for smallholder and commercial farmers alike.
Compared to the current application methods the novelty of this invention lies in the biodegradable smart capsule system that releases bioagents only upon detecting rhizosphere-specific triggers, such as root exudates, soil moisture levels, or pathogen activity.
Unlike conventional methods that apply bioagents uniformly and passively across the field, this system enables:
• Targeted, site-specific activation of bioagents only at the root zone,
• Responsive release based on real-time biological or chemical cues in the soil,
• Encapsulation of multiple components (bioagents + nutrients/elicitors) in a single, degradable unit,
• Improved colonization efficiency of the bioagents by synchronizing release with the crop’s root development stage.
The invention relates to a biodegradable capsule composition formulated to deliver beneficial bioagents into the rhizosphere in a targeted and sustainable manner. Each capsule comprises three essential components: a microbial core, optional additives, and a biodegradable polymer shell.
The core comprises beneficial microorganisms in an amount ranging from 10% to 40% by weight of the total capsule. The concentration is optimized to maintain high microbial viability during encapsulation and storage while allowing sufficient payload for effective field application. Suitable microorganisms include fungi, bacteria, or combinations thereof. Examples include Trichoderma spp. at concentrations of 10–20% by weight, Bacillus spp. at 15–25% by weight, and Pseudomonas spp. at 10–20% by weight.
To enhance the effectiveness of the microbial payload, optional additives are incorporated in amounts ranging from 1% to 15% by weight. These additives may include micronutrients such as zinc (0.5–2%), iron (1–3%), manganese (0.5–1.5%), or copper (0.5–1%). Plant defense inducers such as salicylic acid, jasmonic acid, or chitosan oligomers may also be included at levels of 1–5% by weight. These additives improve microbial activity, promote plant growth, and activate systemic resistance mechanisms in host plants.
The shell comprises biodegradable polymer material in an amount ranging from 45% to 75% by weight of the capsule. Suitable polymers include alginate (30–50% by weight), chitosan (10–20% by weight), gelatin (5–10% by weight), or combinations thereof. These polymers are selected for their biocompatibility, ability to encapsulate sensitive microbes, and natural biodegradability in soil environments.
Embedded within the shell are enzyme- or moisture-sensitive additives in concentrations ranging from 2% to 8% by weight. These additives are designed to respond specifically to rhizosphere conditions. For example, cellulase- or pectinase-sensitive cross-linkers can degrade in the presence of pathogen-secreted enzymes, while moisture-sensitive additives can activate under high soil moisture typical of root zones. This ensures targeted release of bioagents only when needed.
The preparation process begins by suspending the bioagents at 10–40% by weight in a protective medium. This medium may contain stabilizers such as trehalose or skim milk powder at 1–3% levels to improve microbial survival. Optional micronutrients or elicitors are added in the specified ranges before extrusion.

The mixture is then extruded into a solution of biodegradable polymer comprising 45–75% by weight of the capsule. In one embodiment, alginate at 2–3% (w/v) solution is used. The extruded droplets are subjected to cross-linking, typically in a 1–5% calcium chloride bath, to create a stable polymer matrix. The resulting capsules are dried to a semi-soft state to balance ease of handling with retention of microbial viability.
The capsules, when applied to soil or coated onto seeds, remain dormant in bulk soil conditions. Activation occurs upon exposure to root exudates, soil moisture, or pathogen enzymes. This controlled degradation of the polymer shell releases the microbial payload directly in the rhizosphere, ensuring precise colonization and efficient pathogen suppression.
By synchronizing microbial release with rhizosphere triggers, the invention enhances bioagent survival rates, reduces wastage of inputs, and ensures sustained crop protection. The composition’s ratio of core to shell ensures both protection during storage and effective release under field conditions.
The invention is environmentally friendly due to the complete biodegradability of the capsule shell and its ability to leave no harmful residues. It is scalable for diverse crops and adaptable for different soil conditions by modifying polymer concentrations, capsule size, and additive ratios.
Best Method of Working
The best method of working involves encapsulating bioagents in a biodegradable polymer matrix using wet encapsulation and cross-linking techniques. Capsules are prepared with alginate or chitosan polymers and loaded with a mixture of bioagents and optional micronutrients. The capsules are semi-dried to enhance shelf life and ease of application.
During use, the capsules are applied to transplant holes or mixed with compost during sowing. Once placed in the soil, they remain inactive until they encounter root exudates and rhizosphere-specific triggers. This activates controlled degradation of the shell, releasing viable bioagents precisely at the root zone. The bioagents colonize the rhizosphere, suppress pathogens, and promote crop health effectively.
Field and greenhouse trials were conducted to evaluate the performance of the biodegradable smart capsule system compared to conventional methods such as broadcasting and soil drenching. Crops including tomato, chili, and groundnut were selected, and soilborne pathogens such as Fusarium oxysporum, Rhizoctonia solani, and Pythium spp. were introduced under controlled conditions.
In greenhouse experiments, capsules containing 20% Trichoderma harzianum, 2% micronutrient mix, and 65% alginate-based shell demonstrated a 72% reduction in root rot incidence, compared to 38% reduction achieved by broadcasting and 44% by soil drenching. The survival rate of bioagents applied through capsules was maintained above 75% after 15 days, whereas survival dropped below 30% for free inoculum applied directly to soil.
In field plots, capsule-treated plants showed improved root colonization, with colony-forming units in the rhizosphere averaging 2.5 × 10⁶ CFU/g soil, compared to 0.9 × 10⁶ CFU/g in broadcasting methods. Capsule-treated crops exhibited stronger plant growth, including 18–22% higher biomass and 15–20% yield improvement relative to untreated controls.
Moisture-responsive and enzyme-sensitive capsules further demonstrated delayed but synchronized activation, with bioagent release aligning with root development stages. This synchronization reduced wastage and improved pathogen suppression consistency across the cropping cycle.

Table 1: Comparative Efficacy Results
Application Method Disease
Reduction (%) Bioagent Survival after 15 days (%) Rhizosphere Colonization (CFU x10^6 / g soil) Yield Improvement (%)
Capsule System (20% Trichoderma, 2% micronutrients, 65% alginate shell) 72 75 2.5 18
Broadcasting 38 28 0.9 6
Soil Drenching 44 30 1 8
Control
(No Treatment) 0 0 0.3 0
The results clearly establish that the root-responsive biodegradable capsule system significantly outperforms traditional bioagent application techniques. The improved survival of encapsulated microorganisms ensures that bioagents remain viable until reaching the rhizosphere, thereby increasing their colonization efficiency.
By responding specifically to root exudates and pathogen-secreted enzymes, the capsules provide targeted release, minimizing input losses and ensuring effective pathogen suppression exactly where it is needed. This results in stronger disease control, improved plant vigor, and higher yields, demonstrating the agricultural and economic advantages of the system.
The combination of biodegradable polymers, beneficial microorganisms, and optional micronutrients or elicitors provides a synergistic effect, enhancing both plant protection and growth promotion. The technology reduces dependence on chemical fungicides, lowers production costs for farmers, and contributes to sustainable agricultural practices.
The overall conclusion is that the smart capsule system delivers precise, eco-friendly, and scalable bioagent delivery, proving its efficacy as a novel approach for managing soilborne pathogens and enhancing crop productivity.
ADVANTAGES OF THE INVENTION
• Precise application of the bioagents which minimize the wastage of inputs
• Enhanced survival rate and colonization of the bioagents after their application
• Reduces the wastage due to precise application techniques
• Combined application of bioagents and nutrients
• Biodegradable and eco-friendly approach
• Scalable and farmer friendly approach  
, Claims:1. A biodegradable capsule composition for bioagent delivery comprising:
a core containing one or more beneficial microorganisms in an amount ranging from 10% to 40% by weight of the total capsule;
an optional additive selected from micronutrients or plant defense inducers in an amount ranging from 1% to 15% by weight; and
a shell made of biodegradable polymer material in an amount ranging from 45% to 75% by weight, the shell embedded with enzyme- or moisture-sensitive components in an amount ranging from 1% to 10% by weight,
wherein the composition is configured to release the microorganisms upon exposure to rhizosphere-specific triggers.
2. The composition as claimed in claim 1, wherein the microorganisms are selected from fungi, bacteria, or a combination thereof.
3. The composition as claimed in claim 1, wherein the microorganisms comprise species selected from Trichoderma, Bacillus, or Pseudomonas.
4. The composition as claimed in claim 1, wherein the biodegradable polymer is selected from alginate, chitosan, gelatin, or blends thereof, present in an amount ranging from 50% to 70% by weight of the capsule.
5. The composition as claimed in claim 1, wherein the additives comprise micronutrients selected from zinc, iron, manganese, or copper, and plant defense inducers selected from salicylic acid, jasmonic acid, or chitosan oligomers, together comprising 2% to 12% by weight of the capsule.
6. The composition as claimed in claim 1, wherein the capsule shell includes enzyme-sensitive additives responsive to cellulases, pectinases, or proteases, present in amounts ranging from 2% to 8% by weight of the capsule.
7. A process for preparing a biodegradable capsule composition for bioagent delivery, the process comprising:
suspending bioagents at 10% to 40% by weight in a protective medium;
mixing the suspension with optional micronutrients or elicitors at 1% to 15% by weight;
extruding the mixture into a solution containing biodegradable polymer at 45% to 75% by weight;
cross-linking the polymer to form a capsule shell; and
drying the capsule to a semi-soft state suitable for handling and field application.
8. The process as claimed in claim 7, wherein the cross-linking step is carried out in a calcium chloride bath containing 1% to 5% calcium chloride solution to stabilize the capsule structure.