Method development for investigating probiotic effects on fat storage in a Caenorhabditis elegans model (829.33)

Abstract

Gut microbiota via an ability to influence fat synthesis and storage has emerged as an important factor in host adiposity, and a target for its dietary modulation. To examine the role of specific gut bacteria in modulating fat stores and associated mechanisms, we need simple, inexpensive yet powerful animal models. An attractive choice is the nematode C. elegans, in which many pathways of fat storage and energy use are conserved. Based on our previous observations that a probiotic Bifidobacterium longum can reduce triglyceride storage in vitro, our objective was to use the C. elegans model to investigate this in vivo. Our initial attempts at growing C. elegans on B. longum as a food source rather than E. coli OP50 were met with several challenges: reluctance of C. elegans to consume B. longum and preference for OP50, carry‐over of OP50 on the worm surface and in the gut, and non‐comparable growth of C. elegans on B. longum and OP50. By varying the type of medium (solid/liquid) and its composition, increasing B. longum concentration and inhibition of OP50 growth by an antibiotic, we devised a successful method to grow C. elegans on B. longum for over one generation, detect B. longum in the C. elegans gut at numbers comparable to the human small intestine (with no detectable E. coli OP50) and study its impact on triglyceride storage. The method may be adapted to other probiotic bacteria to serve as a screening tool with the scope of investigating detailed mechanisms of action.