Biosynthetic CdS-Thiobacillus thioparus hybrid for solar-driven carbon dioxide fixation

Synergistically combining biological whole-cell bacteria with man-made semiconductor materials innovates the way for sustainable solar-driven CO_(2)fixation,showing great promise to break through the bottleneck in traditional chemical photocatalyst systems.However,most of the biohybrids require uneconomical organic nutrients and anaerobic conditions for the successful cultivation of the bacteria to sustain the CO_(2)fixation,which severely limits their economic viability and applicability for practical application.Herein,we present an inorganic-biological hybrid system composed of obligate autotrophic bacteria Thiobacillus thioparus(T.thioparus)and CdS nanoparticles(NPs)biologically precipitated on the bacterial surface,which can achieve efficient CO_(2)fixation based entirely on cost-effective inorganic salts and without the restriction of anaerobic conditions.The optimized interface between CdS NPs and T.thioparus formed by biological precipitation plays an essential role for T.thioparus efficiently receiving photogenerated electrons from CdS NPs and thus changing the autotrophic way from chemoautotroph to photoautotroph.As a result,the CdS-T.thioparus biohybrid realizes the solar-driven CO_(2)fixation to produce multi-carbon glutamate synthase and biomass under visible-light irradiation with CO_(2)as the only carbon source.This work provides significant inspiration for the further exploration of the solar-driven self-replicating biocatalytic system to achieve CO_(2)fixation and conversion.

Abundance and Diversity of RuBisCO Genes Responsible for CO_2 Fixation in Arid Soils of Northwest China

Arid soils where water and nutrients are scarce occupy over 30% of the Earth's total surface. However, the microbial autotrophy in the harsh environments remains largely unexplored. In this study, the abundance and diversity of autotrophic bacteria were investigated, by quantifying and profiling the large subunit genes of ribulose-1,5-bisphosphate carboxylase/oxygenase(Ru Bis CO) form I(cbb L) responsible for CO2 fixation, in the arid soils under three typical plant types(Haloxylon ammodendron, Cleistogenes chinensis,and Reaumuria soongorica) in Northwest China. The bacterial communities in the soils were also characterized using the 16 S r RNA gene. Abundance of red-like autotrophic bacteria ranged from 3.94 × 105 to 1.51 × 106 copies g-1dry soil and those of green-like autotrophic bacteria ranged from 1.15 × 106 to 2.08 × 106 copies g-1dry soil. Abundance of both red- and green-like autotrophic bacteria did not significantly differ among the soils under different plant types. The autotrophic bacteria identified with the cbb L gene primer were mainly affiliated with Alphaproteobacteria, Betaproteobacteria and an uncultured bacterial group, which were not detected in the 16 S r RNA library. In addition, 25.9% and 8.1% of the 16 S r RNA genes were affiliated with Cyanobacteria in the soils under H. ammodendron and R. soongorica, respectively. However, no Cyanobacteria-affiliated cbb L genes were detected in the same soils. The results suggested that microbial autotrophic CO2 fixation might be significant in the carbon cycling of arid soils, which warrants further exploration.