Altered bacterial metabolism, not coenzyme Q content, is responsible for the lifespan extension in Caenorhabditis elegans fed an Escherichia coli diet lacking coenzyme Q

Summary Coenzyme Q n is a fully substituted benzoquinone containing a polyisoprene tail of distinct numbers (n) of isoprene groups. Caenorhabditis elegans fed Escherichia coli devoid of Q 8 have a significant lifespan extension when compared to C. elegans fed a standard ‘Q‐replete’ E. coli diet. Here we examine possible mechanisms for the lifespan extension caused by the Q‐less E. coli diet. A bioassay for Q uptake shows that a water‐soluble formulation of Q 10 is effectively taken up by both clk‐1 mutant and wild‐type nematodes, but does not reverse lifespan extension mediated by the Q‐less E. coli diet, indicating that lifespan extension is not due to the absence of dietary Q per se. The enhanced longevity mediated by the Q‐less E. coli diet cannot be attributed to dietary restriction, different Qn isoforms, reduced pathogenesis or slowed growth of the Q‐less E. coli , and in fact requires E. coli viability. Q‐less E. coli have defects in respiratory metabolism. C. elegans fed Q‐replete E. coli mutants with similarly impaired respiratory metabolism due to defects in complex V also show a pronounced lifespan extension, although not as dramatic as those fed the respiratory deficient Q‐less E. coli diet. The data suggest that feeding respiratory incompetent E. coli , whether Q‐less or Q‐replete, produces a robust life extension in wild‐type C. elegans . We believe that the fermentation‐based metabolism of the E. coli diet is an important parameter of C. elegans longevity.