Intestinal Microbiome Transplant in ALS

Inclusion Criteria: * Diagnosis of ALS according to Gold Coast Criteria * Age: 18+ years at enrollment * Fast-progressing (ALSFRS-R change of at least 1.5 points per month between last 2 measurements at screening) * Modestly but not severely affected (ALSFRS-R score at or above 24 at screening) * Able to swallow capsules and expected to be able to for the duration of the trial (ALSFRS-R "swallowing" score of 3 or 4 at screening) * Expected to survive for the duration of the trial * Taking any combination of riluzole, edaravone, and/or tofersen at a stable dose for 30 days prior to screening, or not taking any of these and not expected to during the study. * Capable of giving written consent. * If sexually active, must agree to use contraceptive or abstinence for duration of treatment. * Females of child-bearing age must have negative pregnancy test at screening. Exclusion Criteria: * Concurrent illness or laboratory abnormalities that could confound the measurement of ALS progression or the microbiome or interfere with the ability to complete the study. * Taking probiotics, nutraceuticals, or herbal remedies within 2 weeks of screening * Taking antibiotics within 3 months of screening. * Taking any investigational study drug within 30 days of screening or five half-lives of the prior agent. * Previous exposure to MTT. * Pregnancy. * Known specific food allergy with anaphylaxis * Other co-morbid conditions that, in the opinion of the study investigator, place the participant at increased risk of complications, interfere with study participation or compliance, or confound study objectives.