Does anyone know what will happen after feeding worm with dead bacteria? If they will live a longer lifespan?
yes. published by the kenyon lab… they used uv killed bacteria. if memory serves it’s a ~2005 genetics paper (but my memory stinks and I’m in a hurry). :
hope this helps
Thanks a lot!!! But i did not find the paper. 
Could u tell me the title of the paper?
Regarding what happens when worms are fed dead bacteria, this was first done a long time ago, and is fairly standard practice when drugs are being tested and there are concerns that the E. coli may metabolize the drugs. I don’t know what is the best, most useful, or (especially) first reference for feeding dead bacteria to your worms, but Google searches for “uv killed OP50” or “heat killed OP50” will get you many, many references that should lead you in the right direction.
Specifically with regard to lifespan, I’m not sure. My recollection is similar to what AVSamuelson said, ie that someone showed that living bacteria are harmful to aging worms, compared to dead bacteria. That’s my recollection, but I haven’t been able quickly to find the paper in question. On the other hand, with some searches, perhaps not all that well designed, one paper I did find was Davies and Hart (2008), which doesn’t seem to support my recollection:
Untreated controls fed live bacteria had significantly more offspring than those fed dead bacteria: 17 vs 10 larvae per adult (Fig. 1; P < 0.05). There was no significant difference in the time for 50% of the worms to die, 11 vs 12 days, but there was a large and significant difference in terms of 100% mortality: 28 vs 19 days, P < 0.05 (Fig. 2).
AV Samuelson, your memory isn’t as bad as you think. It’s a 2002 Genetics paper from the Kenyon lab:
Garigan D, Hsu AL, Fraser AG, Kamath RS, Ahringer J, Kenyon C. Genetic analysis of tissue aging in Caenorhabditis elegans: a role for heat-shock factor
and bacterial proliferation. Genetics. 2002 Jul;161(3):1101-12. PubMed PMID: 12136014; PubMed Central PMCID: PMC1462187.
Good luck!