Fig 1 -

Real time evolution of (a) pH and (b) OD_750nm for MICP experiments without the presence of calcite seeds for the first 550 min of the reaction. Note that the first shown data point of the measurement is taken 4 min after the start of the reaction (= 0 min). The signal of the OD_750nm correlates with the amount of CaCO₃ in the sample. Dashed vertical lines mark the time-point of maximum pH. The OD in the legend shows the OD_600nm of the bacteria dilution before adding to the crystallization solution. The error bars of the three parallel measurements in the real time pH evolution are in order of magnitude of the size of the shown data point symbols. (c) Optical microscope time-series of precipitation process for bacteria dilution D1-C3 (OD_600nm = 0.89) without calcite seeds present for different time-points of the reaction: (i) 0 min, (ii) 14 min, (iii) 23 min, (iv) 47 min, (v) 54 min, (vi) 88 min, (vii) 148 min, (viii) 240 min, and (ix) 21 h. The magnified area on the left shows an area where no calcite will nucleate during the experiment. The magnified area on the right shows an area where a calcite crystal will nucleate. (d) Micrographs of precipitated crystals after 21 h reaction time for (1) D1-C1_us, (2) D2-C1_us, (3) D3-C1_us, and (4) D4-C1_us without the presence of calcite seeds. The scale-bar in (c) and (d) is 150 μm.