What Are One Health Probiotics?
One Health probiotics are microbial strains that confer benefits not only to humans but also to animals, plants and the environment. Unlike conventional probiotics, which are typically selected for gastrointestinal survival and immunomodulation in humans, One Health probiotics are evaluated for additional traits: inhibition of zoonotic pathogens, enhancement of plant growth (as PGPR), improvement of soil structure, bioremediation of organic pollutants, and even adsorption of heavy metals or microplastics. Lactic acid bacteria are ideal candidates because many carry GRAS (Generally Recognized as Safe) or QPS (Qualified Presumption of Safety) status and have a long history of safe use in food fermentation.
The GRAS‑to‑Grass Concept
In our preprint “From GRAS to Grass: Lactic Acid Bacteria as One Health Probiotics for Plant Growth, Bioremediation, Soil Quality, Food Safety, and Public Health”, we propose a conceptual shift. LAB should no longer be seen only as human‑centric probiotics but as multi‑host, cross‑domain agents that bridge established food‑safety credentials (GRAS) to applications in plant, soil and environmental stewardship (grass). This vision requires standardised field trials, mechanistic omics studies, and clear regulatory pathways – all of which guide our research at HOPE Lab.
Traditional Fermented Foods as Reservoirs of Autochthonous LAB
Bangladesh has a rich heritage of traditional fermented and dairy beverages – borhani, laban, mattha, sugarcane juice, and date palm sap – that naturally harbour diverse LAB communities. Our lab has systematically isolated and characterised LAB from these sources. For example, from borhani we identified Limosilactobacillus fermentum LAB‑1, Levilactobacillus brevis LAB‑5, and Weissella confusa LAB‑11, all showing broad‑spectrum antimicrobial activity against foodborne and clinical pathogens. From laban we characterised Pediococcus pentosaceus L1 and Streptococcus thermophilus L3 with excellent tolerance to gut‑like stress, adhesion properties and milk‑coagulation ability. From mattha we isolated Streptococcus thermophilus M2, which combines probiotic traits with rapid milk coagulation and exopolysaccharide production. Most recently, from sugarcane juice we obtained multifunctional LAB strains that not only survive gastrointestinal transit but also enhance food preservation by reducing microbial loads in perishable foods.
These studies demonstrate that traditional beverages are reservoirs of autochthonous LAB with strain‑specific health‑promoting and technological properties – and they are already safely consumed.
Evaluating Probiotic Properties and Safety
For each LAB isolate, we perform a comprehensive in vitro evaluation. This includes tolerance to low pH, bile salts and phenol; adhesion to intestinal mucus and solvents (autoaggregation and coaggregation); antagonism against bacterial and fungal pathogens; antioxidant capacity; and antibiotic susceptibility profiling. We also assess technological traits such as exopolysaccharide production, milk coagulation, and biopreservation potential. Genomic analysis complements these assays, identifying genes for adhesion, stress response, antimicrobial peptides (bacteriocins), vitamin synthesis and nu‑traceuticals. Our published genome of L. fermentum LAB‑1 revealed pathways for EPS, acetoin, butanediol and multiple antimicrobial compounds – a blueprint for rational probiotic selection.
Extending LAB to Plant Growth and Soil Health
The same LAB that benefit human gut can also promote plant growth. We have tested several LAB isolates for plant growth‑promoting rhizobacteria (PGPR) traits – auxin production, phosphate solubilisation, nitrogen fixation, and siderophore secretion. In pot and field trials with chrysanthemum, LAB‑based consortia significantly increased root and shoot length, biomass, and stress tolerance. Moreover, LAB can suppress phytopathogens through the production of organic acids, hydrogen peroxide and antifungal metabolites, offering an eco‑friendly alternative to chemical pesticides. By applying LAB to soil or as seed coatings, we aim to reduce chemical fertiliser dependence while enhancing crop resilience – a direct contribution to sustainable agriculture.
Environmental Applications: Bioremediation and Food Safety
The One Health probiotic concept also embraces environmental functions. Selected LAB can biosorb heavy metals (lead, cadmium, arsenic) from contaminated water, transform organic pollutants, and even adsorb microplastics. In the food chain, LAB act as natural preservatives by inhibiting spoilage and pathogenic bacteria on raw meat, fish and vegetables. Our own work has demonstrated that LAB from sugarcane juice reduce microbial loads in perishable foods, pointing to applications in food safety without synthetic additives. These environmental and food‑safety roles are integral to the One Health cycle, protecting human health by securing the safety of our food and environment.
We are currently expanding our collection of One Health LAB by exploring less‑studied traditional foods and by characterising LAB from non‑dairy, plant‑based sources. We are also conducting small‑scale field trials with LAB‑based biofertilisers and biopreservatives. Genomic and metabolomic profiling of the most promising strains will guide the development of tailored consortia for specific One Health outcomes – whether improving gut health, boosting crop yield, or cleaning polluted water.
