Identification of Lactobacillus strains with probiotic features from the bottlenose dolphin (Tursiops truncatus)

AIMS: In order to develop complementary health management strategies for marine mammals, we used culture-based and culture-independent approaches to identify gastrointestinal lactobacilli of the common bottlenose dolphin, Tursiops truncatus. METHODS AND RESULTS: We screened 307 bacterial isolates from oral and rectal swabs, milk and gastric fluid, collected from 38 dolphins in the U.S. Navy Marine Mammal Program, for potentially beneficial features. We focused our search on lactobacilli and evaluated their ability to modulate TNF secretion by host cells and inhibit growth of pathogens. We recovered Lactobacillus salivarius strains which secreted factors that stimulated TNF production by human monocytoid cells. These Lact. salivarius isolates inhibited growth of selected marine mammal and human bacterial pathogens. In addition, we identified a novel Lactobacillus species by culture and direct sequencing with 96·3% 16S rDNA sequence similarity to Lactobacillus ceti. CONCLUSIONS: Dolphin-derived Lact. salivarius isolates possess features making them candidate probiotics for clinical studies in marine mammals. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to isolate lactobacilli from dolphins, including a novel Lactobacillus species and a new strain of Lact. salivarius, with potential for veterinary probiotic applications. The isolation and identification of novel Lactobacillus spp. and other indigenous microbes from bottlenose dolphins will enable the study of the biology of symbiotic members of the dolphin microbiota and facilitate the understanding of the microbiomes of these unique animals.