The human gastrointestinal tract harbours \ 40 trillion microbial cells, far outnumbering the cell number, and therefore the genetic content of its host. How this genetically diverse bacterial (collectively referred as 'microbiota') co-resident modulates host homeostasis is largely unknown. We are increasing gaining a better understanding how the microbes modulate mucosal and systemic metabolic/immune and organ systems including the kidney, heart and the brain. Therapeutic targeting of the gastrointestinal (GI) microbiota may help improve clinical outcomes in conditions as diverse as arthritis, cardiovascular disease, and cancer. In contrast to other organ systems, studies investigating the role of the microbiota in modulating clinical outcomes in renal transplantation lags behind. The aim of the study is to examine (a) how alterations in the urinary and GI microbiota and associated metabolites impact on host immunity after renal transplantation, and (b) whether such changes are correlated with post-transplant complications, such as rejection, development of de novo donor specific antibodies, metabolic complications (e.g post-transplant diabetes) and infections. Participants will be followed before and up to twelve months post-transplantation, and, longitudinal microbial data will be correlated with in-depth immune phenotyping and clinical end-points to define the impact that changes in urinary and GI microbial ecology have on kidney transplant outcomes.