人體腸道內的微生物協助消化食物及輔助營養素吸收，是整體健康的重要部分。這張手工上色的掃描式電子顯微鏡圖像顯示，人類排泄物中有大量且多樣的細菌。PHOTOGRAPH BY MARTIN OEGGERLI, MICRONAUT. KINDLY SUPPORTED BY UNIVERSITY HOSPITAL BASEL AND SCHOOL OF LIFE SCIENCES, FHNW