Investigation of the effect of kefir on Caenorhabditis elegans' lifespan and thermotolerance

Aging is an irreversible and fatal process which causes loss of function of organism. In modern times, development in medicine and increased quality of life give rise to increased lifespan. Caenorhabditis elegans is one of the model organism widely used in aging studies. The worm is economical to cultivate, and gives rapid result due to its about one month lifespan. Thus, it is useful in biological and medical research. Kefir is a fermented milk product which is made using kefir grains originated from Caucasia. There are two types of kefir, the culture kefir, which is produced industrially, and the other one is grain kefir, which is produced traditionally. Kefir's positive impact on human health is known. Some studies showed that lactic acid bacteria in the kefir enhanced resistance against tumors and infections in humans and animals bodies. In this study we aimed to determine effect of kefir on C. elegans's lifespan under different temperature by using two types of kefir. Within this scope two different experimental groups were performed. In these experiments control groups were fed with E. coli, and the others were fed culture kefir and grain kefir. Firstly control group compared with the others which were fed culture and grain kefir at non-lethal heat shock temperature (37oC) for C. elegans. And then, same comparison repeated at optimum growth temperature, that is 20oC for C. elegans. As a result, there is % 29 increasing on lifespan of C. elegans which were fed with culture kefir and % 22 increasing on lifespan of C. elegans were fed with grain kefir at 37oC. On the other hand, we couldn't explain the meaning of results obtained from comparison made at 20oC.