Table 1.
Strains and plasmids used in this study.
Figure 1.
Growth of S. denitrificans DSM-1251 under different cultivation conditions.
S. denitrificans DSM-1251 cells were grown in DSMZ medium 113 containing thiosulfate (18.8 mM, filled marker) or without thiosulfate (open marker). The headspace was completely exchanged with H2/CO2 (80%/20%) (square) or with N2/CO2 (80%/20%) (triangle). Error bars indicate the standard deviations from measurements of three cultures.
Figure 2.
In vivo hydrogen consumption in S. denitrificans DSM-1251.
S. denitrificans DSM-1251 cells were grown anaerobically in DSMZ medium 113 either with thiosulfate (18.8 mM) or without thiosulfate. On the first day of inoculation, the headspace of each sample was exchanged with H2/CO2 (80%/20%). The H2 concentration in the headspace was measured with gas chromatography. A control experiment was set up to exclude hydrogen leakage from the vessels. Medium = control, medium without inoculated S. denitrificans DSM-1251; S. den. = inoculation with 0.5 mL of S. denitrificans DSM-1251 pre-culture at day 1. Error bars of “Medium” and “S. den.” indicate the standard deviations from three independent experiments.
Figure 3.
Nitrate (A) and thiosulfate (B) consumption of S. denitrificans DSM-1251 under different cultivation conditions.
S. denitrificans DSM-1251 cells were grown in DSMZ medium 113 containing thiosulfate (18.8 mM, filled marker) or without thiosulfate (open marker). The headspace was completely exchanged with H2/CO2 (80%/20%) (square) or with N2/CO2 (80%/20%) (triangle). Error bars indicate the standard deviations from measurements of three cultures.
Figure 4.
Transcript of hydB (Suden_1435) in S. denitrificans DSM-1251.
S. denitrificans DSM-1251 cells were grown in DSMZ medium 113 with thiosulfate (18.8 mM) and H2/CO2 (80%/20%) in the headspace. The relative transcription levels of hydB were quantified by RT-qPCR and normalized to the reference gene rpoD (housekeeping sigma factor). The transcription level of hydB after 3 days was set as 1. Error bars denote standard deviations from three independent experiments.
Figure 5.
Hydrogen uptake activity of the native and recombinant hydrogenase (HydB) from S. denitrificans.
Hydrogen uptake activity was measured in the membrane fractions of S. denitrificans grown without and with thiosulfate (18.8 mM) and for the recombinant version of the large subunit (HydB). The large subunit of the periplasmic hydrogenase (hydB) was cloned into the vector pBBR1MCS-2 and expressed heterologously in S. oneidensis ΔhyaB. The empty vector in S. oneidensis ΔhyaB was used as negative control. Error bars denote standard deviations from three independent measurements.