DESC:FIELD OF INVENTION
The present invention relates to microbial retardant composition. The present invention specifically relates to a bio-based microbial retardant which is readily biodegradable and hence presents a greener option compared to chemical biocides.

BACKGROUND
The key environmental challenges faced by many industries is unwanted microbial growth in water and the associated issues due the unwanted bacterial growth. The different industry sectors dealing with excess water and carrying organic carbonaceous materials face a similar challenge in terms of unwanted microbial growth. Eventually it all contributes to deteriorating quality of water resulting in septic conditions, increasing the COD, BOD, TDS, & microbial count. The treatment of such contaminated water is not only a big challenge but also an environmental concern involved in the disposal of such wastewater. Conventionally, combination of hypo & biocides is used abundantly as the key treatment method for microbial control and the problems associated with it. The complexity of the water treatment is decided by the quantum of microbial growth and the application sector, such as food, pharma, paint, emulsions, pulp & paper, etc. Biocide utilization has its own limitations in terms of microbial resistance and needs frequent changeover of the program.

Also, in most cases water treatment needs to be free of toxic chemicals, which becomes a challenge and requires significant efforts in terms of the unit operations & selection of treatment chemicals, the water treatments being one of the most extensively studied subjects, several water treatment compositions and chemicals have been researched and presented in the prior art, like the patent application US2023312610 A2 titled as “Anti-microbial compositions” discusses compounds, compositions, methods of forming/preparing such compounds and compositions, and uses for sanitizing and/or substantially removing biofilms and microorganisms living within or around biofilms. The present invention, in particular, relates to compounds of formula Mn(P) wherein the n is an integer from 2 to 6; each M is independently a metal ion; as described herein which can be used in wound treatments, wound dressings, medical devices, water treatments, food processing and dental care biofilms.

Another patent application KR102312611 B1 titled as “Anti-Microbial Polyurea Composition For Eco-Friendly Water Treatment Facilities And Waterproof And Anti Corrosion Method Of Use Thereof” where the present invention discusses a new waterproofing material composition that can overcome the problems of the waterproofing material composition and substantially use the antibacterial function, and provided are an antibacterial polyurea composition for eco-friendly water treatment facilities, which is harmless to workers when used in water treatment facilities and prevents harmful substances from leaching from a waterproof coating film, thereby preventing stored water from being contaminated by the waterproof coating film, and a waterproofing method using the same.

Yet another patent application US2005191365 A2 titled as “antimicrobial food additive and treatment for cooked food, water and wastewater” which discusses a composition of matter with antimicrobial and antibacterial properties for treatment of water, wastewater, processed food and for use as a food additive is provided.

Antimicrobial composition inhibits cellular growth of known pathogenic, indicator and spoilage organisms, such as salmonella, staphylococcus, listeria, E-coli, aerobic and anerobic organisms in wastewater and the like. The antimicrobial composition of the present invention is useful in many situations and conditions in need of disinfectants and sanitizers. One of the primary benefits of the antimicrobial agent is that it inhibits the growth of bacteria that have become antibiotic resistant. In addition, the antimicrobial composition herein does not have any known toxicity to humans or the environment.

Though several technologies discuss compositions of antimicrobial in nature, however none of the prior arts discuss a sustainable solution of microbial retardants which are completely bio-based and readily biodegradable in nature. The present invention discusses a bio-based composition/ product for effective replacement of conventional chemical-based biocides & hypo as the treatment chemicals for wastewater, In-Can preservation & surface preservation. The product discussed herein is biobased in origin with varied applications such as treatment of stagnant ETP water, surface coating emulsions, rubber emulsions, paints, and industrial work surface, process vessels, water holding tanks, water treatment utilities, etc. None of the prior arts discuss a readily biodegradable & biobased formulation using plant-based ingredients in combination with active ingredients produced using fermentation processes.

OBJECTIVES
The primary objective of the present invention is to provide a bio-based microbial retardant composition.

It is another objective of the present invention to provide a method of preparation of bio-based biodegradable microbial retardant composition.

Another objective of the present invention to provide a bio-based composition and method of preparation of the same using lactic acid, tween 80, glutaraldehyde, neem oil along with or without preservative as one of its core components.

It is yet another objective of the present invention to provide a bio-based composition and its preparation method, which retards the microbial growth selectively.

It is also an objective of the present invention to provide a bio-based composition and method of preparation, wherein the formulation retards the logarithmic growth of the microorganism.
It is also the objective of the present invention to provide a formulation composition and its preparation method wherein the formulation makes it very difficult for microbes to develop resistance.

Another objective of the present invention is to achieve a potential reduction in the pathogenic & harmful microbial growth in the water and/or on the surface using this novel formulation.

SUMMARY
The following summary is provided to facilitate a clear understanding of the new features in the disclosed embodiment, and it is not intended to be a full, detailed description. A detailed description of all the aspects of the disclosed invention can be understood by reviewing the full specification, the drawing and the claims and the abstract, as a whole.

The present invention discusses a biobased antimicrobial retardant comprising lactic acid, tween 80, glutaraldehyde, neem oil along with or without preservative as one of its core components. And its method of preparation comprises:
a) Take the appropriate quantity of water in an empty vessel. Add the required quantity of lactic acid under stirring maintaining the pH in the range of 2.5-3.5.
b) Add glutaraldehyde solution and stir the mixture for 20-30 minutes. In a separate vessel, take optimum quantity of tween 80 and homogenized with neem oil.
c) Add the homogenized slurry into the water-based mixture prepared in a separate vessel and stir for 20-30 mins under agitation.
d) Add trace quantities of preservative in the final formulation to prevent any primary level of contamination if any through the water or any of the ingredients. Stir the mixture for 15-20 minutes.

The novel composition uses various plant based & fermentation based natural ingredients to deliver a selective & efficient microbial retardant property.

The novel bio-based composition works with a combinational approach of selective inhibition of gram (-) bacteria, fungus & algae and retarding the logarithmic growth of the said microorganisms.

One of the most unique features of the formulation with selected ingredients makes the final product very difficult for microbes to develop resistance.

DETAILED DESCRIPTION OF THE DRAWING
Figure 1: illustrates the nutrient plate of untreated effluent (Left) and treated effluent (Right)
Figure 2: Illustrates the bactaslyde test for TBC at different product dosages
Figure 3: Illustrates the zone of inhibition for bacteria and fungus at different product dosages.
Fig 4 illustrates a visual representation graph of biodegradability over time, where biodegradability increases as days progress, with the composition reaching 99.95% biodegradation.
Fig. 5 illustrates the biobased carbon content of the composition, as determined by ASTM D6866-24 Method B (AMS). The figure shows that 89% of the carbon content is biobased, while the remaining 11% is fossil carbon. The pie chart represents the breakdown of biobased carbon and fossil carbon, with additional data including the percent modern carbon (88.27%) and the atmospheric adjustment factor (99.7%).
Fig. 6 illustrates the log reduction in bacterial growth over 9 generations. The graph compares the microbial retardant (shown as G1 to G9) against the blank (untreated sample), demonstrating the sustained antimicrobial activity of the composition. The data shows a consistent log reduction in bacterial growth across all nine generations, indicating the effectiveness of the microbial retardant over successive microbial generations.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The principles of operation, design configurations and evaluation values in these non-limiting examples can be varied and are merely cited to illustrate at least one embodiment of the invention, without limiting the scope thereof.

The embodiments will be described in detail with corresponding marked references to the drawings, in which the illustrative components of the invention are outlined. The embodiments disclosed herein can be expressed in different forms and should not be considered as limited to the listed embodiments in the disclosed invention. The various embodiments outlined in the subsequent sections are construed such that it provides a complete and a thorough understanding of the disclosed invention, by clearly describing the scope of the invention, for those skilled in the art. The present invention discusses a bio-based and easily biodegradable greener microbial retardant which works with a combinational approach of Selective inhibition of gram (-) bacteria, fungi, algae and retarding the logarithmic growth of microorganisms.

The novel composition uses various plant based & fermentation based natural ingredients to deliver a selective & efficient microbial retardant property. The unique formulation blend with selected ingredients makes the final product very difficult for microbes to develop resistance. The novel technology uses various plant based & fermentation based natural ingredients to deliver a selective & efficient microbial retardant property. The unique formulation blend with selected ingredients makes the final product, very difficult for microbes to develop resistance. Biobased formulation details & chemistry.

Different formulations have been made at the R&D lab and tested for its microbial retardant properties. The ingredients are selected from the category of fermentation produced organic acids, natural essential oils, biobased aldehydes & sugar based fatty acid esters. The ingredient selection has made it efficient against the gram (-) bacteria. All the formulations are tested for its efficacy against the most common contamination causing bacteria including E-coli, Saeureus & pseudomonas and fungus including A. Niger, and algae including Scenedesmus sp. The selected ingredients are known for their microbial retardant properties and independently work with a different mode of action for inhibiting or retarding microbial growth. The combination of different modes of action ensures that the selected microorganisms will not develop any resistance against the final product.

The developed formulation will not only replace the commercial biocides & hypo but also will facilitate the presence and growth of the good, essential microbial flora in the process water system. The resulting formulation is an effective solution against microbial contaminants in water or water-based products.

The formulation comprises of:
a. Lactic acid
b. Tween 80
c. Glutaraldehyde
d. Neem oil
e. Preservative- DB20
as its core components or ingredients

All the ingredients are biobased & readily biodegradable. Each of the ingredients works with different mechanisms & all together delivers a synergistic effect of microbial retardation. The following are the different microbial retardant mechanisms delivered by the selected ingredients.

a) Lactic acid
It provides an acidic environment unfavourable for the growth of many pathogenic and spoilage microorganisms. Acids are generally thought to exert their microbial retardant effect by interfering with the maintenance of cell membrane potential, inhibiting active transport, reducing intracellular pH, and inhibiting a variety of metabolic functions thus causing cell apoptosis. They have a very broad mode of action and inhibit gram-negative bacteria, yeast, fungus, algae and molds. Different microorganisms vary considerably in their sensitivity to lactic acid with varying pH. At pH 5.0, lactic acid was inhibited towards spore-forming bacteria but was ineffective against yeasts and molds.

b) Tween 80
It is a poly ethoxylated sugar surfactant with mild anti-microbial properties. It exhibits selective microbial retardant action against a very few micro-organisms by altering the conditions of cell membrane. It works by inhibiting the transcription and translation process, ultimately leading to cell death.

c) Glutaraldehyde
Glutaraldehyde is a saturated dialdehyde and widely used as chemical sterilant. The microbial retardant property of glutaraldehyde is mainly due to the alkylation of hydroxyl, carbonyl and amino groups which affect DNA, RNA, and protein synthesis. In addition to this, it binds to the outer membrane of most of the gram-negative organisms and inhibits the membrane transport mechanisms leading to apoptosis.

d) Neem oil
Neem oil has an active compound called ‘Azadirachtin’ along with ‘nimbidin’ which shows major anti-microbial property. It restricts the biofilm formation by inhibiting the cell adhesion on the surface. ‘Nimbidin’ being a class of triterpenoids, it works by either of the following mechanisms-Alters the cytoplasmic membrane leading to apoptosis. Disrupts the cell wall by inhibiting peptization of the growing peptidoglycan chain and by inhibiting the enzymes for cell wall synthesis.

Binds to the DNA binding site of topoisomerase II, while a few also bind to the ATP binding site and inhibit metabolic pathways. All the above-mentioned compounds exhibit microbial retardant properties individually but are not sufficient to show maximum efficiency. However, the selective combination of the ingredients in a formulation works by synergistic effect. The following synergistic effects play a major role in delivering the desired results:

Essential oil penetration across the cell membrane system requires a surfactant (Tween 80) which helps reduce the surface tension across the cell wall thus increasing the cell permeability. It has been extensively studied and proved that micro-emulsions of essential oils will favor more effective anti-microbial action than the self-oils.

Lactic acid and glutaraldehyde work in synergy assuming that, the acidic environment created by the lactic acid favors the stability of glutaraldehyde and prevents the polymerization of glutaraldehyde. When the product is diluted at the actual application, the glutaraldehyde maintains its active state and exhibits its higher biological activity.

EXPERIMENTATION AND RESULTS
Microbial analysis of the effluent sample before & after treatment
The results obtained showed that the product has proven to be a good microbial retardant formulation. The effluent sample treated with the formulation has substantially reduced the microbial load from 105 cfu to 102 cfu indicating the 99% microbial reduction as shown in figure 1. Also, from the physical parameters, it is observed that the treatment is not leading to an increase in the COD of the system which generally happens in the case of conventional treatments with biocides & hypo.

The results are further validated by conducting a ‘bactaslyde’ test (dip test for microbial count enumeration) which supports the significant reduction in the microbial count. Figure 2 summarizes the obtained data. The results are further validated by conducting a zone of inhibition studies for bacteria and fungus which supports the substantial growth suppression. Figure 3 summarizes the obtained data.
With higher concentration of formulation in the treatment from 0.01% to 0.1% has shown enhanced reduction in the microbial count when compared to the control. Also, the lowest concentration of formulation has shown substantial reduction in the microbial load. The results show that the formulation is an effective microbial retardant agent for any type of water treatment or water-based products.

The objective of the study was to develop a biobased microbial retardant formulation. The developed technology has used a novel combination of ingredients to make a unique formulation as microbial retarding agent. The formulation is highly efficient against the spoilage microbes, more specifically gram-negative bacteria, fungi, algae & other pathogenic organisms. The novel formulation will retard the unwanted microbial growth without generating microbial resistance. The formulation helps in avoiding the septic conditions of stagnant water which results in odor formation, In-can preservation of packed aqueous emulsions, surface contamination in plant & machinery and water borne contaminations. Overall formulation is an effective, environmentally friendly alternative for the existing chemical biocide programs.

One embodiment of the invention is a bio-based microbial retardant composition comprising:
Lactic acid, ranging from 2% v/v to 20% v/v of the composition, sufficient to maintain the pH of the composition in the range of 1.5 to 3.5, facilitating immediate acidification of the medium upon application.
Glutaraldehyde, ranging from 0.5% v/v to 10% v/v of the composition, effective to stabilize the composition in the acidic environment provided by lactic acid and to prevent polymerization, enabling immediate activation upon dilution during application.

Polysorbate 80 (Tween 80), ranging from 1% v/v to 15% v/v of the composition, sufficient to emulsify Melia Azadirachta Seed Oil (Neem oil) and ensure immediate dispersion and membrane penetration for enhanced antimicrobial action.

Melia Azadirachta Seed Oil (Neem oil), ranging from 0.05% v/v to 5.5% v/v of the composition, contributing to the antimicrobial properties of the composition.

Methylchloroisothiazolinone (Preservative), ranging from 0.01% v/v to 1% v/v of the composition, effective to inhibit initial contamination and ensure immediate microbial load suppression during storage and handling.

Wherein the said composition is readily biodegradable, exhibiting at least 70% degradation within 28 days as determined by OECD 301D, and is configured to exhibit broad-spectrum antimicrobial activity and retard microbial growth without inducing microbial resistance.

In another aspect, the bio-based microbial retardant composition as claimed, wherein the glutaraldehyde is stabilized by the acidic environment provided by the lactic acid to prevent polymerization and enable immediate activation upon dilution during application.

A further embodiment of the invention involves the bio-based microbial retardant composition, wherein Neem oil is emulsified using Polysorbate 80 (Tween 80) to form a microemulsion, thereby ensuring immediate dispersion and membrane penetration for enhanced antimicrobial action.

In yet another aspect, the bio-based microbial retardant composition, wherein the preservative is selected to inhibit initial contamination and ensure immediate microbial load suppression during storage and handling.

The bio-based microbial retardant composition, wherein the synergistic combination of the ingredients results in selective inhibition of gram-negative bacteria, fungi, and algae, and immediate suppression of logarithmic microbial growth across multiple microbial generations.
In another embodiment, the bio-based microbial retardant composition, wherein the composition retains antimicrobial efficacy across at least nine successive microbial generations, providing immediate and sustained log reduction in microbial load without the development of resistance.

In Fig 6, the log reduction in bacterial growth over 9 generations is shown. The graph compares the microbial retardant (shown as G1 to G9) against the blank (untreated sample), demonstrating the sustained antimicrobial activity of the composition. The data shows a consistent log reduction in bacterial growth across all nine generations, indicating the effectiveness of the microbial retardant over successive microbial generations.

A further embodiment is a bio-based microbial retardant composition, wherein the composition is effective at concentrations as low as 0.01% to 0.1% and exhibits immediate microbial inhibition in water or water-based medium.

Another aspect of the invention involves a bio-based microbial retardant composition, wherein the composition retains its antimicrobial activity and provides broad-spectrum efficacy against gram-negative bacteria, fungi, and algae at various concentrations, demonstrating sustained and effective microbial load reduction over time.

An aspect of the invention also includes a method of preparing the bio-based microbial retardant composition, comprising the following steps:
Adding lactic acid to water under continuous stirring to achieve a pH in the range of 1.5 to 3.5.
Adding glutaraldehyde solution to the mixture and stirring for 20 to 30 minutes.
Separately homogenizing Polysorbate 80 (Tween 80) with neem oil to form a microemulsion.
Adding microemulsion to the lactic acid and glutaraldehyde mixture under agitation for 20 to 30 minutes.
Optionally adding a preservative and stirring the final mixture for 15 to 20 minutes to obtain microbial retardant composition with immediate functional activity.

The present invention discusses a bio-based microbial retardant composition that is highly effective in controlling microbial growth in various applications. The composition is readily biodegradable and exhibits broad-spectrum antimicrobial activity against gram-negative bacteria, fungi, and algae, without causing microbial resistance. The following results substantiate the efficacy of the microbial retardant composition:

Readily Biodegradable Composition: The composition is confirmed to be readily biodegradable, exhibiting 99.95% biodegradation within 28 days, as per the OECD 301D test method. This ensures that the product has minimal environmental impact and degrades efficiently after use.
Wherein the graph, Fig 4 illustrates a visual representation graph of biodegradability over time, where biodegradability increases as days progress, with the composition reaching 99.95% biodegradation.
Biobased Carbon Content: The composition has been analyzed using ASTM D6866-24 Method B (AMS) TOC for its biobased carbon content. The results indicate that 89% of the carbon content is derived from renewable sources (biobased), with only 11% being fossil carbon. This highlights the eco-friendly nature of the composition.
Wherein Fig. 5 illustrates the biobased carbon content of the composition, as determined by ASTM D6866-24 Method B (AMS). The figure shows that 89% of the carbon content is biobased, while the remaining 11% is fossil carbon. The pie chart represents the breakdown of biobased carbon and fossil carbon, with additional data including the percent modern carbon (88.27%) and the atmospheric adjustment factor (99.7%).

Absence of Volatile Organic Compounds (VOCs): The composition was screened using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). No volatile organic compounds, including benzene, toluene, and xylene, were detected, confirming that the composition is free from harmful VOCs.

Broad-Spectrum Antimicrobial Activity: The zone of inhibition tests demonstrated that the composition is effective in inhibiting the growth of various bacteria, fungi, and algae. The product was tested at concentrations as low as 10 mg%, showing significant inhibition against bacteria such as E. coli, P. aeruginosa, S. aureus, fungi like A. Niger, and algae species like Scenedesmus sp. These results confirm that the microbial retardant exhibits broad-spectrum antimicrobial properties.

BACTERIA (+: Detected; -: Undetected)
Microbial retardant (%) 0.01 0.03 0.06 0.12 0.24 0.50
E. coli + + - - - -
P. aeruginosa + + + - - -
S. aureus + + + - - -
FUNGUS (+: Detected; -: Undetected)
A. Niger + + - - - -
ALGAE (+: Detected; -: Undetected)
Scenedesmus sp. NA + + + - -

Minimal Inhibitory Concentration (MIC) Studies: The MIC tests showed that the composition effectively inhibits the growth of bacteria, fungi, and algae at low concentrations:
E. coli (0.06%)
P. aeruginosa and S. aureus (0.12%)
A. Niger (0.06%)
Scenedesmus sp. (0.5%)
These findings confirm the composition's ability to act as a potent antimicrobial agent even at minimal concentrations.
Logarithmic Growth Retardation Over Generations: A study conducted to assess the long-term effectiveness of the composition over multiple generations revealed that the microbial retardant consistently reduced bacterial growth across nine generations of E. coli, demonstrating its sustained antimicrobial activity without the development of resistance.

Microbial Resistance Studies:
Bacterial Challenge Study (ASTM D 2574:2016): The composition was tested against a mixture of gram-negative bacteria, fungi, and yeast. The results showed complete microbial inhibition at a minimum concentration of 1%, with no resistance observed even after four weeks of repetitive exposure.
Plating Results Score
No Bacterial Recovery 0
Trace of Contamination (1-9 colonies) 1
Light Contamination (10-99 colonies) 2
Moderate Contamination (>100 colonies) 3
Heavy Contamination (Continuous growth of Bacteria) 4

RESULTS
Sample Number Sample Description Day 1 (Bacteria) Day 1 (Fungus) Day 3 (Bacteria) Day 3 (Fungus) Day 7 (Bacteria) Day 7 (Fungus)
240269/S01 Microbial Retardant (0.5%) 2 1 2 1 1 1
240269/S02 Microbial Retardant (1%) 0 0 0 0 0 0
240269/S03 Microbial Retardant (2%) 0 0 0 0 0 0
240269/S04 Microbial Retardant (3%) 0 0 3 3 4 4
Lab Control 4 4 4 4 3 3

Fungal Challenge Study (ASTM D 5590:2017): The composition demonstrated complete inhibition against fungal species such as Aspergillus niger, even at a minimum concentration of 5%, with no development of resistance over a four-week period.
Plating Results Score
No Bacterial Recovery 0
Trace of Contamination (1-9 colonies) 1
Light Contamination (10-99 colonies) 2
Moderate Contamination (>100 colonies) 3
Heavy Contamination (Continuous growth of Bacteria) 4

RESULTS
Sample Description Test Organism 1 Week Rating 2 Weeks Rating 3 Weeks Rating 4 Weeks Rating
2402697/S01 Mixed Spores No zone 1 No zone 1 No zone 1 No zone 2
2402697/S01 Spores of A. pullulans No zone 2 No zone 2 No zone 2 No zone 2
2402697/S02 Mixed Spores No zone 0 No zone 0 No zone 0 No zone 0
2402697/S02 Spores of A. pullulans No zone 0 No zone 0 No zone 0 No zone 0
Whatman Filter paper - Viability control Mixed Spores No zone 3 No zone 3 No zone 3 No zone 4
Whatman Filter paper - Viability control Spores of A. pullulans No zone 4 No zone 4 No zone 4 No zone 4

Algal Challenge Study (ASTM D 5589:2009): The formulation was highly effective against algae species like Scenedesmus sp., showing complete inhibition at a minimum concentration of 5%, and retained its efficacy over the four-week testing period.
Plating Results Score
No Bacterial Recovery 0
Trace of Contamination (1-9 colonies) 1
Light Contamination (10-99 colonies) 2
Moderate Contamination (>100 colonies) 3
Heavy Contamination (Continuous growth of Bacteria) 4

Sample Description Test Organism 1 Week Zone of Inhibition 1 Week Rating 2 Weeks Zone of Inhibition 2 Weeks Rating 3 Weeks Zone of Inhibition 3 Weeks Rating 4 Weeks Zone of Inhibition 4 Weeks Rating
2402703/S01 Mixed Algae No zone 0 No zone 0 No zone 1 No zone 2
2402703/S02 Mixed Algae No zone 0 No zone 0 No zone 0 No zone 0
Whatman Filter paper - Viability control Mixed Algae No zone 4 No zone 4 No zone 4 No zone 4

The combination of lactic acid, glutaraldehyde, Polysorbate 80, neem oil, and preservatives in the composition results in a synergistic effect that enhances antimicrobial action, ensuring that the formulation remains effective against microbial growth over time. Additionally, the formulation's ability to maintain its antimicrobial properties without promoting microbial resistance makes it a valuable alternative to traditional chemical biocides. ,CLAIMS:WE CLAIM:
1. A bio-based microbial retardant composition comprising:
-Lactic acid, ranging from 2% v/v to 20% v/v of the composition, sufficient to maintain the pH of the composition in the range of 1.5 to 3.5 and facilitate immediate acidification of the medium upon application;
-Glutaraldehyde, ranging from 0.5% v/v to 10% v/v of the composition, effective to stabilize the composition in the acidic environment provided by lactic acid and to prevent polymerization, enabling immediate activation upon dilution during application;
-Polysorbate 80 (Tween 80), ranging from 1% v/v to 15% v/v of the composition, sufficient to emulsify Melia Azadirachta Seed Oil (Neem oil) and ensure immediate dispersion and membrane penetration for enhanced antimicrobial action;
-Melia Azadirachta Seed Oil (Neem oil), ranging from 0.05% v/v to 5.5% v/v of the composition, effective to contribute to the antimicrobial properties of the composition;
-Methylchloroisothiazolinone, ranging from 0.01% v/v to 1% v/v of the composition, effective to inhibit initial contamination and ensure immediate microbial load suppression during storage and handling;
wherein the said composition is readily biodegradable, exhibiting at least 70% degradation within 28 days as determined by OECD 301D, and is configured to exhibit broad-spectrum antimicrobial activity and retard microbial growth without inducing microbial resistance.
2. The bio-based microbial retardant composition as claimed in claim 1, wherein the glutaraldehyde is stabilized by the acidic environment provided by the lactic acid to prevent polymerization and enable immediate activation upon dilution during application.
3. The bio-based microbial retardant composition as claimed in claim 1, wherein Neem oil is emulsified using Polysorbate 80 (Tween 80) to form a microemulsion, thereby ensuring immediate dispersion and membrane penetration for enhanced antimicrobial action.
4. The bio-based microbial retardant composition as claimed in claim 1, wherein the preservative is selected to inhibit initial contamination and ensure immediate microbial load suppression during storage and handling.
5. The bio-based microbial retardant composition as claimed in any of the preceding claims, wherein the synergistic combination of the ingredients results in selective inhibition of gram-negative bacteria, fungi, and algae, and immediate suppression of logarithmic microbial growth across multiple microbial generations.
6. The bio-based microbial retardant composition as claimed in claim 1, wherein the composition retains antimicrobial efficacy across at least nine successive microbial generations, providing immediate and sustained log reduction in microbial load without the development of resistance.
7. The bio-based microbial retardant composition as claimed in claim 1, wherein the composition is effective at concentrations as low as 0.01% to 0.1% and exhibits immediate microbial inhibition in water or water-based media.
8. The bio-based microbial retardant composition as claimed in claim 1, wherein the composition retains its antimicrobial activity and provides broad-spectrum efficacy against gram-negative bacteria, fungi, and algae at various concentrations, demonstrating sustained and effective microbial load reduction over time.

9. A method of preparing a bio-based microbial retardant composition as claimed in claim 1, the method comprising:
a. adding lactic acid to water under continuous stirring to achieve a pH in the range of 1.5 to 3.5;
b. adding glutaraldehyde solution to the mixture and stirring for 20 to 30 minutes;
c. separately homogenizing Polysorbate 80 (Tween 80) with neem oil to form a microemulsion;
d. adding the microemulsion to the lactic acid and glutaraldehyde mixture under agitation for 20 to 30 minutes; and
e. optionally adding a preservative and stirring the final mixture for 15 to 20 minutes to obtain the microbial retardant composition with immediate functional activity.