Sargassum seaweed has inundated Caribbean coastlines, disrupting ecosystems while presenting opportunities for sustainable products like liquid biofertilizers. This study evaluated the microbiological and biosecurity profiles of two liquid biofertilizers produced in the Dominican Republic: Sargassum-based (SBLB-INTEC) and conventional (LB-BANELINO). Both exhibited essential minerals (K, Ca, Mg) and low heavy metal concentrations, meeting agricultural safety standards. Metagenomic analysis (16S rRNA) identified diverse bacterial and archaeal communities, mainly consisting of beneficial taxa such as Firmicutes, Proteobacteria, and Methanobacteria, with no detectable pathogens. Ecotoxicological assays with Lactuca sativa showed phytotoxicity at high concentrations, mitigated by dilution (≤6.25%) and pH adjustment (7.0), achieving germination indexes above 80%. These results suggest that Sargassum-based biofertilizers could be a viable alternative for enhancing soil fertility and promoting sustainable crop production, particularly in coastal agricultural systems where conventional fertilizers may be limited or environmentally harmful. Moreover, this study highlights the critical role of ecotoxicological testing in ensuring biofertilizer safety and underscores Sargassum’s potential as a renewable resource for sustainable farming.

Sargassum seaweed is increasingly abundant in the Caribbean, creating ecological disruption but also providing biomass for agricultural inputs. This study compares the microbial diversity and safety of a Sargassum ‐based liquid biofertilizer (SBLB‐INTEC) with those of a conventional product (LB‐BANELINO) using 16S rRNA amplicon sequencing, rather than culture‐dependent methods. Both formulations contained key nutrients (K, Ca, and Mg) and low levels of heavy metals. They harbored dense but relatively simple bacterial communities dominated by Firmicutes, particularly Bacilli, with Proteobacteria and other phyla at lower abundances. Staphylococcus (Staphylococcaceae) was highly abundant in both products, while SBLB‐INTEC showed a somewhat more balanced community, including Delftia and other Comamonadaceae. Shannon diversity tended to be higher in SBLB‐INTEC, but differences in alpha‐ and beta‐diversity between formulations were not statistically significant. Because 16S data cannot distinguish viable from nonviable cells or resolve strain‐level pathogenicity, these results do not prove the absence of pathogens; instead, they provide a genus‐level baseline to guide targeted culture, qPCR, and functional assays. Overall, the combination of a favorable chemical profile and microbial groups commonly associated with nutrient cycling and plant‐associated functions suggests that SBLB‐INTEC could become a valuable component of integrated nutrient management in tropical agriculture, offering hope for a more sustainable future pending confirmatory plant‐response and biosafety studies. We recommend integrating these microbial data into a national biofertilizer monitoring framework, combining metagenomic surveys with targeted qPCR and resistance gene screening.

Since the year 2011 the Caribbean region has seen a massive seasonal influx of pelagic Sargassum. The proliferation of this algae adversely affects the island nations by deteriorating their coastal and marine ecosystems, like coral reefs; decreasing biodiversity, and lowering water quality, while also diminishing tourism revenue, which may be the economic backbone of most countries in this region. The proliferation of Sargassum seaweed and its effects on Guadalupe and Dominican Republic are directly linked to Sustainable Development Goal (SDG) 14, which seeks to "conserve and sustainably use the oceans, seas and marine resources for sustainable development". The impact from the seasonal assault on both nations has led to different mitigation, usage, and conservation strategies that can be developed into a comprehensive program for the management and valorization of sargassum, which in turn can become an opportunity for sustainable development.This work will present the strategies followed by a group of universities within the Dominican Republic’s interuniversity Sargassum research network which tackle the arrivals through four fundamental research lines:- Monitoring and prediction: The Dominican Republic is developing a prediction model based on aerial and satellite imagery, GPS tracking and ocean current models which will try and identify sargassum accumulation from trajectories through monitoring of sargassum windrows. This work includes the deployment of a nanosatellite focused on sargassum monitoring in coastal waters.- Containment and collection: the group has made advances in sargassum containment through sea barriers and water collection in order to guarantee high quality biomass for value aggregated processing.- Valorization: Sargassum is being processed through modular systems to obtain biomass that can be converted into energy (via anaerobic digestion or gasification), biofertilizers, biochars, activated carbon (through both conventional and microwave pyrolysis), alginate, and biocomposites of fibers and biopolymers.- Impact assessment and management: experiences in management research will be shared, especially in the analysis of risk perception and the development of a comprehensive management model for sargassum in the Dominican Republic, which guarantees compliance with SDG 14 by 2030, as proposed by the United Nations.

The recurrent influx of pelagic Sargassum spp. along Caribbean coastlines poses a significant environmental challenge while offering potential as a resource-recovery agricultural input. However, agricultural reuse of Sargassum biomass raises concerns regarding salinity and trace-metal distribution within the soil–plant–food continuum. This study evaluated the short-term elemental response to a Sargassum-Based Liquid Biofertilizer (SBLB) produced via controlled anaerobic fermentation, using tomato (Solanum lycopersicum L.) grown under greenhouse conditions. Raw biomass, fermented biofertilizer, irrigation water, soils, vegetative tissues, and fruits were chemically characterized. Elemental concentrations were quantified by ICP–OES and ICP-MS and treatment effects were analyzed using one-way and two-way ANOVA (p < 0.05). Anaerobic fermentation resulted in lower measured concentrations of sodium, arsenic, and selected trace elements in the liquid fraction relative to raw biomass. SBLB application increased soil macronutrient availability (N, P, K, Ca, Mg), while soil trace-metal concentrations remained within international reference ranges during the experimental period. Metals of concern (As, Cd, Pb, Ni, Cr) showed no detectable short-term enrichment in soils, vegetative tissues, or fruits relative to controls. In tomato fruits, arsenic, cadmium, and lead were below the limit of quantification across all treatments. Within the experimental timeframe, SBLB application was not associated with detectable trace-element accumulation in the soil–plant system. Long-term field studies and detailed soil physicochemical characterization are required to evaluate cumulative effects under repeated applications.