Safety, Tolerability, and Pharmacodynamics of SYNB8802v1 in Subjects With History of Gastric Bypass Surgery or Short-bowel Syndrome

Inclusion Criteria: * Age ≥ 18 to ≤ 74 years. * Able and willing to voluntarily complete the informed consent process. * Available for, and agree to, all study procedures, including fixed diet, feces, urine, and blood * collection, follow-up visits, and compliance with all study procedures. * History of gastric bypass surgery (at least 12 months prior to Day 1) or short-bowel * syndrome. * If taking probiotic supplements (enriched foods excluded), has been on a stable, well tolerated dose for at least 2 weeks prior to Day 1. * Women of childbearing potential must have a negative pregnancy test (human chorionic * gonadotropin) at screening and at baseline prior to the start of IMP. * Screening laboratory evaluations (e.g., chemistry panel, complete blood count with * differential, prothrombin time, urinalysis) and electrocardiogram (ECG) must be within * normal limits or judged not to be clinically significant by the investigator. Subjects with * known diabetes should be well controlled and have an A1c of ≤ 8% within 3 months prior to Day 1. * Agree to abstain from tobacco/nicotine use for the duration of the inpatient stay. * Subjects who are HIV positive, on therapy with normal CD4 counts and undetectable viral loads, can be included. Exclusion Criteria: * Acute or chronic medical (including COVID-19 infection), surgical, psychiatric, or social condition or laboratory abnormality (except those that can be explained by malabsorption) that may increase subject risk associated with study participation, compromise adherence to study procedures and requirements, or may confound interpretation of results and, in the judgment of the investigator, would make the subject inappropriate for enrollment. * Estimated glomerular filtration rate \< 45 mL/min/1.73 m2. * History of kidney stones. * Subjects taking supplements that contain vitamin C should continue to use their supplements at a constant dose throughout the study, having maintained a constant dose for 2 weeks prior to screening. * Known primary hyperoxaluria. * Pregnant or lactating. * Administration or ingestion of any type of systemic (e.g., oral or intravenous) antibiotic within 5 half-lives of the agent prior to Day 1. Exception: topical antibiotics are allowed. * Any co-morbid condition that may necessitate antibiotic use or disrupt the controlled diet during the study period. * Intolerance of, or allergic reaction to, EcN, all PPIs, or any of the ingredients in SYNB8802v1 or placebo formulations. * Dependence on alcohol or drugs of abuse. * Current, immunodeficiency disorder including autoimmune, except for controlled HIV (see inclusion Criterion #9). disorders. * Administration or ingestion of an investigational drug within 30 days or 5 half-lives, whichever is longer, prior to screening visit, or current enrollment in an investigational study. * History of inflammatory bowel disease.