Fig. 4: Hydrogels containing Laccase⁺-riboF-Lysis⁺ strain have enhanced oxidative activity.

a Schematic overview of the genetic circuit used in the construction of Laccase⁺-riboF-Lysis⁺ strain. b Visual assay of hydrogel ABTS oxidation activity over four days. (i) Subsection of a hydrogel containing strain Laccase⁺-riboF-Lysis⁺. (ii) Subsection of a hydrogel containing the Laccase⁻-riboF-Lysis⁻ control strain. The scale bar on the bottom left corresponds to 10 mm. Experiment was repeated thrice with similar results based on independent samples. c Time-course of the oxidation of ABTS in reaction buffer after the addition of hydrogels containing either the Laccase⁻-riboF-Lysis⁻ control strain, Laccase⁺-riboF-Lysis⁺ strain, or an unloaded hydrogel control. Experiments were conducted in triplicate from independent samples, n = 3. *, **, ***, and ns indicate P values ≤ 0.05, 0.01, 0.001, and not significant, respectively. P values were calculated using a two-tailed Student’s t test. The P values in c (from left to right) are 0.0975, 0.0001, 0.0864, 0.0123, 0.0232, 0.0117, 0.0093, 0.0153, 0.0091, 0.0077, 0.0742, 0.0075, 0.0051, 0.0700, and 0.0050. Data are mean ± S.D. d Percent decolorization of indigo carmine (0.1 mg/mL in BG-11) by hydrogels printed with either Laccase⁻-riboF-Lysis⁻ or Laccase⁺-riboF-Lysis⁺ strains or unloaded hydrogel after incubation for 10 days. Experiments were conducted in triplicate from independent samples, n = 3. *, **, ***, and ns indicate P values ≤ 0.05, 0.01, 0.001, and not significant, respectively. P values were calculated using a two-tailed Student’s t test. The P values in d (from left to right) are 0.0033, 0.0056, and 0.0004. Data are mean ± S.D. e Representative images of hydrogels at incubation time 0 (left) and after 10 days of incubation (right). (Roman numerals indicate the addition of i) hydrogel printed with Laccase⁺-riboF-Lysis⁺, ii) hydrogel printed with Laccase⁻-riboF-Lysis⁻, iii) unloaded hydrogel, iv) BG-11 with dye only.) Scale bars in upper left correspond to 10 mm. Experiment was repeated thrice based on independent samples.