Title : Functional and probiotic characterization of lactiplantibacillus curvatus isolated from the dolphin gut microbiota
Abstract:
Conventional probiotics are typically derived from a narrow spectrum of microbial species, which may inherently limit the diversity of their functional attributes and mechanisms of action. Conversely, microorganisms isolated from hosts adapted to extreme environments often exhibit superior resilience and possess unique biological properties that could be harnessed for therapeutic use. Within this framework, the present study aimed to comprehensively characterize the probiotic potential of a?Lactiplantibacillus curvatus?strain previously isolated from the intestinal microbiota of a dolphin, under controlled in vitro conditions. To establish its safety profile, the strain was first subjected to a series of evaluations, including hemolytic activity, antibiotic susceptibility—via both disc diffusion and broth microdilution methods—and PCR-based screening for virulence genes. Notably, the strain exhibited γ-hemolytic activity and was susceptible to nine antibiotics based on EFSA-established cutoff values, while PCR analyses confirmed the absence of virulence-associated gene sequences. Furthermore, simulated gastrointestinal assays demonstrated that the strain maintained a viability of 7.235 log?? CFU/mL, thereby indicating strong survival potential within the gastrointestinal environment. For functional characterization, Caco-2 intestinal epithelial cells were exposed to bacterial concentrations ranging from 10? to 10? CFU/mL, and MTT assay results showed no significant cytotoxic effects, thus validating the use of the highest concentration for subsequent analyses. The immunomodulatory properties of the strain were then investigated using RAW 264.7 murine macrophages, wherein ELISA findings revealed a marked downregulation of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), coupled with an upregulation of the anti-inflammatory cytokine IL-10. Taken together, these findings strongly support the notion that L. curvatus represents a promising and functionally robust next-generation probiotic candidate with potential applications in gastrointestinal health and immunological homeostasis.
