Recycling Sargassum spp. Biomass for Sustainable Biocontrol in Agriculture: A Circular Approach

Abstract

The increasing frequency of Sargassum spp. blooms represents a global environmental challenge, impacting coastal ecosystems and requiring sustainable management strategies. This study evaluates the potential of Sargassum spp. extract as an encapsulating material for biological pest control, contributing to marine waste valorization. Pelagic Sargassum spp. collected from the Havana coast was processed to obtain an alginate-rich extract, which was used to encapsulate Beauveria bassiana conidia via ionic gelation. FTIR confirmed characteristic carboxylate absorption bands, indicating structural similarities with commercial alginate, while TGA demonstrated comparable thermal behavior. Beads exhibited consistent dimensions (0.5–3 mm) with irregular post-drying shapes. Encapsulation efficiency yielded a conidial concentration of 1.43 × 10⁸ conidia per mL, ensuring retention within the matrix. Long-term viability was confirmed as conidia remained viable and able to grow after six months, potentially benefiting from extract-derived compounds. These findings highlight the potential of repurposing Sargassum spp. for sustainable agricultural applications, advancing environmentally friendly pest management while addressing the ecological burden of excessive Sargassum accumulation.

1. Introduction

The excessive accumulation of the brown macroalgae Sargassum spp. along coastal regions has become a growing environmental concern, affecting marine ecosystems, biodiversity, and coastal economies. Classified as marine waste, its presence poses challenges for coastal management and tourism, but also opportunities for sustainable resource utilization within a circular economy framework. One of the most studied applications of Sargassum spp. is its use as a raw material for alginate extraction, a biodegradable polysaccharide widely used in pharmaceutical, food, and biotechnology industries [1,2].

Traditionally, alginate is extracted from brown seaweeds through multi-step processes that involve pre-treatment, extraction, and purification. These steps refine the polysaccharide to achieve the desired physicochemical properties for various industrial uses [3]. However, exploring more direct applications of Sargassum spp. biomass—such as the use of unpurified alginate-rich extracts—could enhance sustainability and efficiency in biotechnological applications.

While marine waste accumulation presents ecological challenges, sustainable resource management can help mitigate its impact. Similarly, agriculture faces environmental concerns, particularly regarding the excessive use of chemical pesticides, which demand alternative solutions aligned with sustainability principles.

Modern agriculture relies heavily on synthetic insecticides to protect crops and maximize yields, yet their indiscriminate use has led to soil degradation, water contamination, and risks to human health [4]. Pesticide residues accumulate in fruits, grains, and vegetables, exposing consumers to toxic compounds and reinforcing the need for environmentally responsible pest control strategies [5]. Sustainable agricultural practices increasingly emphasize biological control methods as a way to reduce reliance on synthetic pesticides [6]. Among these approaches, entomopathogenic fungi—particularly Beauveria bassiana (Hypocreales: Cordycipitaceae)—have gained attention for their effectiveness in controlling arthropod pests without compromising soil health, biodiversity, or food safety [7,8]. B. bassiana is one of the most extensively studied entomopathogenic fungi, known for its ability to infect a broad range of insect pests including aphids, whiteflies, beetles, and lepidopteran larvae. It acts through direct penetration of the insect cuticle, which eliminates the need for ingestion and reduces the risk of resistance development [9,10], making it well-suited for use in integrated pest management (IPM) systems. In Cuba, the strain LBB-1234 from the INISAV microbial culture collection is widely mass-produced by the national network of CREE (Centros de Reproducción de Entomófagos y Entomopatógenos) and is applied for the biocontrol of pests such as Cylas formicarius (sweet potato weevil), Cosmopolites sordidus (banana weevil), Hypothenemus hampei (coffee berry borer), and Atta insularis (leaf-cutter ant).

Despite its widespread commercialization, B. bassiana-based products face challenges in maintaining conidia viability during storage and field applications, as environmental stressors such as temperature fluctuations, UV exposure, and microbial competition can reduce their effectiveness [11,12]. Encapsulation using natural polymeric matrices has emerged as a promising strategy to protect conidia from adverse conditions, prolonging their shelf life while maintaining their metabolic activity. Felizatti et al. (2021) [13] highlight that encapsulation also helps preserve the genotypic and phenotypic characteristics of microorganisms. Among the various natural polymers used for encapsulation, polysaccharides such as cellulose, starch, gum, chitosan, and alginate stand out for their biocompatibility and biodegradability. Alginate, in particular, enables the formation of stable hydrogel beads through ionic gelation—a simple and efficient method that does not require organic solvents or high temperatures [14,15].

This study introduces an innovative approach by utilizing Sargassum spp. as a natural source of alginate-rich extract for encapsulating Beauveria bassiana conidia, without the need for extensive purification steps. By leveraging marine biomass for biological pest control solutions, this approach contributes to both coastal waste management and sustainable agriculture. The objective of this work is to evaluate the potential of this alginate-rich extract in the formulation of encapsulated conidia through ionic gelation, presenting a biopesticide alternative aligned with circular economy principles.

2. Materials and Methods

2.1. Collection of Sargassum spp.

Seaweed of Sargassum spp. was collected in mesh bags from the northern coastal beach of Havana (23°10′35″ N 82°11′17″ W). The collected Sargassum spp. biomass was cleaned of foreign objects, washed with water, dried in an oven at 60 °C for 72 h, and then ground in an electric mill and sieved (particle size of 2 µm).

2.2. Extraction of Sargassum spp.

The Sargassum spp. extract was obtained by adapting the alginate extraction protocol described by Gómez-Matos et al. (2023) [16], in which only the pre-treatment and extraction steps were performed. The final purification stage was intentionally omitted to preserve a broader spectrum of soluble compounds. The resulting filtrate (Sargassum spp. extract) was stored at room temperature in amber containers.

2.3. Beauveria bassiana Strain and Growth Conditions

Beauveria bassiana strain LBB-1234, from the INISAV culture collection of microorganisms that stem from the insect Hypothenemus hampei (Ferrari, 1867) in Granma province in Cuba, was used in this study. For production of conidial suspension, the fungus was grown on Sabouraud dextrose agar (SDA) in Petri dishes until sporulation for approximately 10 days at 26 ± 1 °C. The conidia were recovered from Petri dishes by scraping off the fungus growth with a sterile spatula and kept in a flask at 4 °C.

2.4. Obtaining Beauveria bassiana Conidia Beads

The Sargassum spp. extract beads were obtained by the ionic gelation method reported by Baldiviezo et al. (2023) [17] with some modifications. A suspension of conidia at 1.2 × 10⁹ conidia per mL was prepared with the Sargassum spp. extract. This suspension was dripped into a 1.5% CaCl₂ solution. The beads obtained were filtered, and washed with distilled water. Furthermore, beads without conidia were obtained using Sargassum spp. extract, as well as beads with conidia, using a commercial sodium alginate rich in guluronic acid residues obtained from the seaweed Laminaria hyperborea (BDH Limited, Poole, UK). The three variants of beads were packaged in glass containers and stored at a low temperature (2–8 °C).

2.5. Characterization of the Sargassum spp. Extract and B. bassiana Beads

2.5.1. Fourier Transform Infrared Spectroscopy (FTIR)

FTIR spectra (IRSpirit, Shimadzu, Tokyo, Japan) were recorded using the attenuated total reflectance (ATR) method, in a wavelength range of 4000 to 600 cm⁻¹, of samples of commercial sodium alginate, the Sargassum spp. extract, and the beads obtained with and without conidia. All spectra were analyzed with the OriginLab 9.0 software. The assignments of the absorption bands recorded in the spectra were based on the works of Ore et al., 2020; Shivakumara & Demappa, 2019 [18,19].

2.5.2. Thermogravimetric Analysis (TGA)

The percentage of mass loss of the samples as a function of temperature was determined with a Mettler Toledo thermogravimetric analyzer (TGA/SDTA 85-F, Columbus, OH, USA). A quantity of 2 mg of each sample was taken and heated in nitrogen from 50 to 650 °C with temperature increments of 20 °C min⁻¹. The results were analyzed with the OriginLab 9.0 software.

2.5.3. Scanning Electron Microscopy

High-Resolution Scanning Electron Microscopy (FESEM) (Zeiss AURIGA Compact, Oberkochen, Germany) was used to observe the surface morphology of beads. The samples were coated with carbon using a vacuum sputter coating machine (Leica EM ACE200, Wetzlar, Germany). Subsequently, they were placed in the 9-sample holder to be introduced into the microscope. The micrographs were taken at 5 and 15 KV.

2.5.4. Growth and Quantification of B. bassiana Conidia Encapsulated in Sargassum spp. Extract

To evaluate the functional viability of encapsulated conidia, intact beads were directly placed on Petri dishes containing Sabouraud dextrose agar (SDA) supplemented with chloramphenicol (0.05 g/L) and incubated at 26 ± 1 °C in darkness. At time zero, colony development was monitored from 72 h to 10 days, and viability was assessed based on the number of beads that produced visible fungal growth with morphology consistent with B. bassiana strain LBB-1234. After six months of storage, beads were again inoculated under the same conditions to qualitatively evaluate the preservation of growth potential; however, no colony counts were performed at this stage.

For conidial quantification, 1 g of encapsulated beads was suspended in 10 mL of 2.5% sodium citrate solution (Titolchimica, Villamarzana, Italy) and stirred for 20 min using a magnetic stirrer (IKA RET basic) to dissolve the matrix and release the conidia. Serial dilutions were prepared in sterile distilled water with Tween 80 (Sigma-Aldrich, St. Louis, MO, USA) (0.01%, v:v), and conidial counts were performed using a Neubauer chamber (Merck, Darsmtatd, Germany) under optical microscopy, following standard microbiological procedures.

3. Results

3.1. Characterization of the Sargassum spp. Extract

The Sargassum spp. extract obtained in this study exhibited a dark brown color and a viscous consistency. To confirm the presence of alginate, the infrared spectra of the extract were compared with those of commercial sodium alginate, as shown in Figure 1. Characteristic functional groups associated with alginate molecules were identified in the extract, including bands corresponding to hydroxyl groups (OH) (band 1) and the asymmetric and symmetric valence vibrations of the carboxylate group (COO⁻) (bands 3 and 4), as detailed in

Table 1. Assignment of bands of the FTIR spectra of the Sargassum spp. extract and commercial sodium alginate.

IR Region (cm−1)	Assignment	Alginate	Assignment	Sargassum Extract	Assignment
3700–3100	νOH and νNH	3433	νOH	3320	νOH and νNH
3000–2800	νCsp3-H	2892	νsCH2	2936	νasCH2
1780–1560	νC=O, νC=C, νasCOO-	1598	νasCOO-	1596	νasCOO-
1600–1400	δOH, δNH and δCH	1306	δOH and δCH	-
1560–1300	νC-O, νsCOO-, νC-N2	1398	νsCOO-	1376	νsCOO-
1070–960	νC-O-C *	1016	νCOC	1024

* Peptide Amide II Band.

.

Below 1400 cm⁻¹, several bands appear that cannot be assigned with certainty. This spectral region, known as the fingerprint area of the molecule, contains various absorption bands related to out-of-plane and in-plane bending of O-H and C-H groups, as well as C-C and C-O valence vibrations. In alginate, the spectral region between 1100 and 900 cm⁻¹ is associated with the pyranose environment, with the most representative band being the absorption around 1000 cm⁻¹, attributed to the C-O-C stretching vibration of the pyranose ring (band 6). This feature is also perceptible in the IR spectrum of the extract, further supporting the presence of alginate.

The thermal decomposition behavior of alginate typically occurs in multiple stages, including dehydration, decomposition, the formation of Na₂CO₃, and the subsequent breakdown of the carbonate phase [20,21,22]. The thermal decomposition profile of the Sargassum spp. extract was compared to that of commercial sodium alginate, as illustrated in Figure 2. The characteristic decomposition stages are observed as distinct “steps” in the thermogram (TGA curve) and as peaks in the differential thermogravimetric curve (DTGA). Additionally, the percentage of free and bound water in the samples is presented in

Table 2. Percentage of free and bound water in samples of commercial alginate and Sargassum extract.

% of H2O	Sodium Alginate	Sargassum Extract
Free	4.55	8.84
Bound	5.05	17.90

.

3.2. Characterization of B. bassiana Conidia Beads

Beads obtained with Sargassum spp. extract exhibited a brown color and generally rounded morphology, with wet bead sizes ranging from 3.0 to 3.5 mm, while dry beads measured from 1.0 to 1.5 mm. The beads formulated with commercial alginate showed similar sizes but displayed a white color due to the purification and bleaching process of the alginate, which results in a transparent dissolution (Figure 3).

FTIR spectra were recorded for both empty beads and beads containing B. bassiana conidia formulated with Sargassum spp. extract. Characteristic absorption bands associated with alginate were observed in all samples, confirming its presence as a structural component of the encapsulating material. Differences between the spectra of empty and conidia-containing beads were detected, particularly in specific regions of the spectrum (Figure 4), suggesting potential molecular variations. Further interpretation of these spectral differences will be discussed in the next section.

At time 0, the conidial viability for the beads formulated with Sargassum spp. extract was 98.3 ± 0.58%, with a conidial concentration of 1.43 × 10⁸ conidia per mL, while beads obtained with commercial sodium alginate showed a viability of 97.0 ± 0.81% and a conidial concentration of 6.42 × 10⁸ conidia per mL. Colonies from both formulations displayed typical B. bassiana morphological features: white, cottony growth reaching 2.0–3.5 cm in diameter on SDA after 10 days at 26 °C, with yellowish reverse coloration and a dusty appearance upon conidial maturation (Figure 5). The conidia were globose in shape (Figure 5).

Scanning electron microscopy (SEM) analysis was conducted on beads obtained with Sargassum spp. extract, with and without conidia. Since conidia were not observed on the outer bead surface, cross-sectional imaging was performed, revealing the presence of conidia within the internal structure of the beads (Figure 6). After six months of storage, further SEM observations of the Sargassum spp. extract-based beads revealed conidiogenous cells with long flask-shaped structures and globose conidia (Figure 6), confirming conidial viability over time.

4. Discussion

Research into innovative formulation techniques, particularly bioencapsulation, has grown significantly in recent years, driven by the increasing demand for microbial biocontrol agents as eco-friendly alternatives to chemical insecticides [23]. Beyond their agricultural relevance, sustainable encapsulation materials derived from marine biomass, such as Sargassum spp., offer a unique opportunity to integrate circular economy principles into biotechnological applications.

4.1. Characterization of the Sargassum spp. Extract

The dark coloration of the Sargassum spp. extract in this study is likely associated with the presence of phenolic compounds, as the algal biomass was not pre-treated with formaldehyde—a common organic solvent used in alkaline extraction to prevent pigmentation in alginate [24,25]. While viscosity is an indicator of alginate presence, this property was not directly assessed in this work. However, FTIR spectroscopy and thermogravimetric analysis provide evidence supporting the presence of this polysaccharide.

In the infrared spectra of the extract, absorption bands appear broader and less intense due to signal overlap from various compounds, including phenolics, nitrogenous compounds, flavonoids, and alkaloids. The characteristic hydroxyl (O-H) stretching band at ~3300 cm⁻¹ can be attributed not only to alginate but also to phenolic compounds, water, and nitrogenous groups (N-H) from peptides and amino acids present in the extract. Additionally, the symmetric vibration band of methylene groups (CH₂, ~2892 cm⁻¹) observed in commercial alginate does not appear in the extract spectrum, instead presenting a shoulder at lower frequency values (~2936 cm⁻¹).

Despite the presence of overlapping signals, the classic absorption bands of the carboxylate group (COO⁻) in alginate—corresponding to asymmetric stretching (~1600 cm⁻¹) and symmetric stretching (~1400 cm⁻¹)—were identified in the extract. The band labeled as “band 5” in the alginate spectrum remains unassigned in the literature, though it has been consistently observed as a moderate-intensity peak (Figure 1). Hong et al. (2021) [26] highlight that the 1500–1200 cm⁻¹ region is considered a “local symmetry” zone, primarily representing CH₂ deformations and C-OH bending in polysaccharides. Gieroba et al. (2023) [27] further support this by assigning a 1314 cm⁻¹ band in cellulose to CH and OH deformations, an assignment that may similarly apply to band 5 in alginate.

The characteristic pyranose ring band appears at a slightly lower frequency (~1024 cm⁻¹) in the extract spectrum, with an additional shoulder at ~1058 cm⁻¹. This feature could be associated with C-C-H and O-C-H ring vibrations or with the presence of other polysaccharides, such as fucoidan, a sulfated polymer commonly found in Sargassum spp., which exhibits absorption bands in the 1200–1270 cm⁻¹, 1010–1060 cm⁻¹, and 900–800 cm⁻¹ ranges [26]. Notably, signals in the 900–800 cm⁻¹ region, often used to distinguish anomeric carbon types and infer the composition of mannuronic (M) and guluronic (G) units in alginate, were absent in our extract—likely due to the FTIR technique employed [18].

The thermal decomposition profile of commercial sodium alginate typically presents three main stages: (1) dehydration below 150 °C, (2) polymer degradation around 300 °C, and (3) formation of Na₂CO₃ near 350 °C [22]. These stages appear as characteristic “steps” in the TGA curve and corresponding peaks in the DTGA curve (Figure 2). The Sargassum spp. extract displays a more complex thermal behavior, though some events resemble those of alginate.

The first major mass loss in the extract occurs near 150 °C and is attributed to water loss. The pronounced weight reduction at this stage suggests a higher moisture content, in line with the elevated levels of free and bound water compared to sodium alginate (Table 2). Notably, the dehydration process between 20 and 200 °C is primarily related to bound water, which in the extract reaches approximately four times the level found in alginate.

Subsequent mass losses are observed around 250–300 °C, reflecting overlapping thermal events. These may correspond to partial degradation of alginate, as well as thermal decomposition of other organic compounds present in the extract. Unlike commercial alginate, no distinct thermal event related to Na₂CO₃ decomposition was observed in either sample, which may be due to the inert nitrogen atmosphere and the 750 °C temperature limit applied in the analysis [20].

The complex thermal behavior of the Sargassum spp. extract, compared to commercial alginate, reflects its composite nature and the presence of various bio-based constituents. This heterogeneity may be advantageous for the protective and functional properties of the encapsulation system, such as conidial shielding during environmental stress or enhanced control over release dynamics in field conditions. Further studies are warranted to explore these potential benefits.

While FTIR and thermogravimetric analyses alone cannot definitively confirm alginate presence due to the coexistence of various organic compounds [28,29,30,31], the ability of the extract to form stable beads in the presence of Ca²⁺ ions (Figure 3) strongly supports the presence of this polysaccharide. This finding demonstrates the potential of Sargassum spp. extract as an alternative encapsulating material, offering a natural and less refined source of alginate for biotechnological applications.

Although the extract obtained in this study exhibits functional properties suitable for encapsulation, future research should focus on optimizing the extraction method to maximize yield and efficiency. Additionally, a detailed chemical characterization will be necessary to better understand the presence of bioactive compounds that may contribute to encapsulation efficiency and long-term conidial stability. These further investigations will enhance the potential of Sargassum spp. as a sustainable biopolymer source, reinforcing its applicability in environmental and agricultural technologies.

4.2. Characterization of B. bassiana Conidia Beads

The dimensions of the beads obtained in this study align with those reported in previous research (0.5–3 mm), both for ionic gelation— the encapsulation method used here—and for fungal capsules where alginate is employed as a polymeric matrix [14,32,33,34]. Additionally, the irregular shape observed in the beads after drying has been previously documented [35]. Several studies have noted that bead size is influenced by factors such as the viscosity, concentration, and flow rate of the alginate solution, as well as the needle diameter used for dripping and the distance between the needle and the CaCl₂ solution [32,33,34].

A key difference observed in the FTIR spectra of the beads (Figure 4) is the decrease in the O-H functional group signal, which appears divided into two smaller bands around 3450 cm⁻¹ and 3300 cm⁻¹. This variation may be associated with changes in the encapsulating material during bead formation. The C-H signal at 2940 cm⁻¹ is more distinguishable in beads containing conidia, potentially due to contributions from the fungal structures in the sample. Moreover, the asymmetric vibration band of the COO⁻ carboxyl group at 1600 cm⁻¹ is reduced in the bead spectra, suggesting alterations in the chemical environment of alginate within the encapsulation matrix.

Encapsulation efficiency is a critical factor in microbial bead formulations. Mancera-López et al. (2018) [14] reported a higher conidial concentration (~1.5 × 10⁸ conidia per mL) in medium-sized (1.5 ± 0.3 mm) and large (2.7 ± 0.3 mm) capsules compared to smaller capsules (8.6 ± 3 µm). The beads obtained in this study exhibit a comparable conidial concentration (1.43 × 10⁸ conidia per mL), indicating that the encapsulation method used was effective in retaining fungal propagules within the matrix.

Previous studies have explored diverse matrices for the encapsulation of B. bassiana, including alginate and bentonite composites, as reported by Batista et al. (2021) [35], who demonstrated that such combinations create protective microenvironments that enhance fungal survival under abiotic stress. Similarly, Felizatti et al. (2021) [13] evaluated formulations using alginate blended with humic acids, cellulose, corn starch, lignin, and soy oil. Their findings confirmed that alginate-based systems allow controlled release of B. bassiana without requiring high temperatures, thus preserving microbial viability. Other works have also shown that ionic gelation methods exert minimal stress on entomopathogenic fungi, supporting their use in maintaining propagule viability during processing and storage [35,36,37]. Compared to previous encapsulation approaches, the Sargassum spp.-based beads produced in this study performed comparably in terms of initial viability, conidial concentration, and fungal development.

Localization of conidia within the inner surface of the beads may enhance fungal protection against external environmental stressors. Notably, after six months of storage, conidia not only remained viable but were also able to grow, likely utilizing carbohydrates present in the beads as nutrients. The presence of phenolic and sulfated compounds in the Sargassum spp. extract may also suggest a potential inhibitory effect on competing microorganisms or target pests. Although this study did not assess such bioactivity, no adverse effects were observed on B. bassiana viability or morphology, either macroscopically or under SEM. These findings highlight the extract’s biocompatibility with the fungus and open the possibility that the matrix may provide additional protection or synergistic effects in the field (Figure 6).

Building on these results, future research should focus on optimizing bead formulation by exploring the effects of polymer concentration, gelation parameters, and matrix composition on fungal viability. Additionally, field trials are essential to validate the biological performance of encapsulated conidia under variable agricultural conditions and to benchmark their efficacy against conventional biopesticide formulations. These investigations will further clarify the potential of Sargassum spp. extract as a sustainable and scalable encapsulation material for integrated pest management.

Despite the promising results observed under laboratory conditions, several limitations must be acknowledged. The use of unpurified Sargassum extracts introduces chemical heterogeneity that may affect formulation reproducibility. Moreover, the environmental behavior of encapsulated conidia—including release dynamics, persistence, and stability—requires validation under real-world conditions. More broadly, the application of Beauveria bassiana as a biopesticide faces ongoing challenges such as production costs, formulation complexity, and sensitivity to abiotic stress factors like UV radiation, temperature, and humidity [8].

Nevertheless, entomopathogenic fungi offer multifaceted ecological advantages beyond pest suppression. Species such as Beauveria and Metarhizium can function as endophytes, stimulate plant growth, and inhibit phytopathogens while serving as reservoirs of bioactive secondary metabolites [38]. With over 170 fungal-based products registered for commercial use, Beauveria spp. have demonstrated broad-spectrum efficacy and are generally recognized as safe for non-target organisms, including pollinators, parasitoids, and vertebrates [10]. However, continued toxicological assessments are recommended to ensure their safety in diverse agroecosystems.

To mitigate environmental and formulation-related constraints, encapsulation—particularly via calcium alginate matrices—provides a protective strategy that enhances fungal viability, handling, and storage potential [11]. While advances have been made in pharmaceutical and cosmetic microencapsulation, translating these techniques to agricultural contexts still faces technical and regulatory hurdles. Overcoming these barriers will require co-formulation with synergistic agents, scalable production platforms, and greater alignment with economic and policy frameworks to facilitate the broader adoption of fungal biocontrol agents.

4.3. Environmental Relevance and Sustainable Applications

The use of Sargassum spp. extract as an encapsulating agent represents a sustainable alternative that aligns with the principles of circular economy and biowaste valorization. By repurposing sargassum biomass, this approach not only reduces environmental burden [39] but also provides a functional material for microbial encapsulation with promising applications in biological control and sustainable agriculture. The ability of the extract to successfully encapsulate Beauveria bassiana conidia demonstrates its potential to replace refined encapsulating agents, offering a lower-cost and environmentally friendly option for biotechnological formulations [40].

Additionally, the presence of phenolic compounds and other bioactive molecules within the extract may contribute to conidial protection, potentially enhancing fungal resilience against environmental stressors. The fact that encapsulated conidia remained viable and able to grow after six months of storage underscores the long-term stability of this formulation. These findings pave the way for innovative pest management strategies, reducing reliance on chemical pesticides while mitigating the ecological impact of Sargassum spp. accumulation. To ensure large-scale viability, future research should focus on optimizing both the extraction process to enhance yield and composition, as well as encapsulation efficiency to improve bead stability and conidial viability.

5. Conclusions

An extract of Sargassum spp. was successfully obtained from drift seaweed, containing sufficient alginate to enable the encapsulation of Beauveria bassiana conidia (1.43 × 10⁸ conidia per mL), which remained viable for 180 days.

The use of Sargassum spp. drift as a raw material for developing an encapsulating matrix for beneficial microorganisms represents a promising strategy for waste valorization and sustainable agriculture. The resulting biopolymer-based beads, containing Beauveria bassiana conidia, offer a biocontrol solution that reduces dependence on synthetic agrochemicals while promoting environmentally friendly agricultural practices.