Dietary induces supersized lipid droplets by enhancing lipogenesis and ER-LD contacts in .

Dietary and symbiotic bacteria can exert powerful influence on metazoan lipid metabolism. Recent studies have emerged that microbiota have a role in animal obesity and related health disorders, but the mechanisms by which bacteria influence lipid storage in their host are unknown. To reduce the complexity of the relationship between gut microbiota and the host, () has been chosen as a model organism to study interspecies interaction. Here, we demonstrate that feeding with an opportunistic pathogenic bacterium () retards growth and promotes excessive neutral lipid storage. Gene expression analysis reveals that dietary induces a lipogenic transcriptional response that includes the SREBP ortholog SBP-1, and fatty acid desaturases FAT-6 and FAT-7. Live imaging and ultrastructural analysis suggest that excess neutral lipid is stored in greatly expanded lipid droplets (LDs), as a result of enhanced endoplasmic reticulum (ER)-LD interaction. We also report that loss of function mutations in in confers resistance to . Dietary induces supersized LDs by enhancing lipogenesis and ER-LD contacts in . This work delineates a new model for understanding microbial regulation of metazoan physiology.