Environmental gradients(环境梯度) As far as food is concerned a practical example is when a dilute syrup is added to the surface of a cup of dense syrup, facultative osmo philic microbes (兼性嗜渗微生物) will select the upper layer of dilute syrup to live in and the obligate osmophiles would choose the bottom layer to live inEnvironmental gradients(环境梯度) As far as food is concerned, a practical example is when a dilute syrup is added to the surface of a cup of dense syrup, facultative osmo philic microbes (兼性嗜渗微生物)will select the upper layer of dilute syrup to live in and the obligate osmophiles would choose the bottom layer to live in