Non-Invasive Microbial Metabolic Activity Sensing at Single Cell Level by Perfusion of Calcein Acetoxymethyl Ester
Fig 8
Metabolic activity sensing under iron limitation at single cell level.
(A) Mean single cell fluorescence traces of all descendants of a progenitor cell are shown under intermittent iron supply. A daughter cell with higher calcein fluorescence than its siblings (light blue arrow) generated growing descendants with increased mean single cell fluorescence traces (light blue lines) in comparison to other descendants of the initial progenitor cell (grey mean single cell fluorescence traces). A single spontaneously non-growing cell changed from a dividing state to a non-growing state loosing esterase activity and intracellular calcein due to lysis (indicated by black arrow, lysed cell shown in (C) and (D), respectively). (B) Mean single cell fluorescence traces of spontaneously non-growing cells of a microcolony are shown. Lysing cells (red lines) lost fluorescence spontaneously after lysis (red arrow). However, they were still detectable as apparently intact cells (end of recognition marked with red asterisks). The mean single cell fluorescence traces of a spontaneously non-growing but metabolically active cell (blue line) are shown in comparison. Mean single cell fluorescence increases shortly after cell birth (blue arrow). (C) A lysed but apparently intact cell (marked with black dashed line) and a cell directly before performing lysis (marked with red dashed line) are depicted. (D) Lysed cells still appear to be intact cells (red dashed line and black dashed line, respectively) after lysis. These non-growing cells showed no calcein fluorescence and were considered to be metabolically non-active. (E) A non-growing but metabolically active cell after re-supply of iron with elevated mean single cell fluorescence (marked by blue dashed line).