Supplemental Material for Neve, et al., 2019

<b>Metabolomics analysis</b> <i>E. coli</i> metabolite profiling was performed at Metabolon, Inc (Durham, NC) with 5 biological replicates of each test bacterial strain (MG1655, OP50, HB101). <i>E. coli</i> colonies were inoculated in LB, grown overnight, and then plated on Nematode Growth Medium (NGM) Agar plates to form lawns for three days at 20°C. Lawns were then scraped off of the surface of the agar and collected in distilled deionized water. Samples were then washed 3 times. Each sample contained approximately 0.1mg of pooled bacterial pellet which was then flash frozen using liquid nitrogen. Metabolomics profiling was performed in the method described previously (Evans <i>et al.</i> 2009). Statistical analysis was performed using Welch’s two-sample t-test to identify compounds that differed significantly between bacterial strains.<br><br><b>Methodology for performing Reproductive Lifespans with Betaine supplementation </b> Reproductive lifespans (RLS) were performed at 20°C on animals that were developmentally synchronized using a variation of the “egg prep” methodology described in (Porta-de-la-Riva <i>et al.</i> 2012). Well-fed animals were raised for two generations on standard NGM plates seeded with OP50. The third generation of animals were plated on antibiotic free NGM plates seeded with the test bacteria, and if necessary, an inducible agent (IPTG) or supplement (Betaine at 20mM during development, and 100mM after L4, based upon plate volume). Upon development to the L4 stage, worms were singled to individual plates containing their specified food source. The animals were then transferred to fresh plates every day at the same time until reproduction cessation, determined as the point when no progeny were produced for three consecutive days. Two days after the individual worms were transferred, plates were checked, and double checked for progeny. Animals that bag or die were noted as censors. Reproductive span curves were calculated using Kaplan-Meier survival analysis and compared using the log-rank test. At least two independent trials were conducted.<br>PCR of stated loci was conducted with primers listed<br>

**代谢组学分析**
大肠杆菌（E. coli）的代谢谱分析由美国北卡罗来纳州达勒姆市的Metabolon公司完成，每个测试菌株（MG1655、OP50、HB101）设置5个生物学重复。将大肠杆菌菌落接种于LB培养基中过夜培养，随后涂布于线虫生长培养基（Nematode Growth Medium，NGM）琼脂平板上，于20℃下培养3天以形成菌苔。随后刮取琼脂表面的菌苔，收集于蒸馏去离子水中，将样本洗涤3次。每份样本包含约0.1mg混合的细菌沉淀，随后用液氮快速冷冻。代谢组学表征按照此前报道的方法完成（Evans等人，2009年）。统计分析采用Welch两样本t检验，以鉴定不同菌株间存在显著差异的代谢物。

**甜菜碱补剂干预下的生殖寿命实验方法**
生殖寿命（Reproductive Lifespan，RLS）实验于20℃下开展，实验动物的发育同步化采用Porta-de-la-Riva等人2012年报道的“卵制备”方法的改良方案。将状态良好的动物在接种了OP50的标准NGM平板上连续培养两代。将第三代动物接种于无抗生素的NGM平板上，该平板接种了测试菌株，必要时添加诱导剂异丙基-β-D-硫代半乳糖苷（IPTG）或补剂（根据平板体积，发育阶段添加20mM甜菜碱，L4期后添加100mM甜菜碱）。待动物发育至L4期时，将单条线虫转移至含有指定食物源的独立平板中。随后每天固定时间将线虫转移至新鲜平板，直至生殖活动停止——生殖停止定义为连续三天未产生后代的时间点。在单条线虫完成转移后的两天，对平板进行两次后代计数检查。出现体内胚胎孵化或死亡的动物记为删失样本。采用Kaplan-Meier生存分析绘制生殖寿命曲线，并通过对数秩（log-rank）检验进行组间比较。所有实验至少独立重复两次。
针对指定基因座的聚合酶链式反应（PCR）采用已列出的引物完成。