Probiotic Microbes Sustain Youthful Serum Testosterone Levels and Testicular Size in Aging Mice. - Poutahidis, Theofilos; Springer, Alex; Levkovich, Tatiana; Qi, Peimin; Varian, Bernard J.; Lakritz, Jessica R.; Ibrahim, Yassin M.; Chatzigiagkos, Antonis; Alm, Eric J.; Erdman, Susan E. (PLoS ONE, 2014)