Project description:Purple phototrophic bacteria (PPB) naturally accept CO2 into their metabolism as a primary redox sink system in photo-heterotrophy. Dedicated use of this feature for developing sustainable processes (e.g., through negative-emissions photo-bioelectrosynthesis) requires a deep knowledge of the inherent metabolic mechanisms. Here we provide evidence of the tuning of the PPB metabolic mechanisms upon redox stressing through negative polarization (-0.4 and -0.8 V vs. Ag/AgCl) in photo-bioelectrochemical devices. Using metaproteomic analysis at both reactor ans species level, we showed that a mixed PPB-culture up-regulates its ability to capture CO2 from organics oxidation through the Calvin-Besson-Bassam cycle and anaplerotic pathways, and the redox imbalance is promoted to polyhydroxyalkanoates production. The ecological relationship of PPB with mutualist bacteria stabilizes the system and opens the door for future development of photo-bioelectrochemical devices focused on CO2 up-cycling.
Project description:The weathering of volcanic minerals makes a significant contribution to the global silicate weathering budget, influencing carbon dioxide drawdown and climate control. Basalt rocks may account for over 30% of the global carbon dioxide drawdown in silicate weathering. Yet the genetics of biological rock weathering are unknown. For the first time, we apply a DNA microarray to investigate the genes involved in weathering by the heavy metal resistant organism, Cupriavidus metallidurans CH34; in particular we investigate the sequestering of iron. The results show that the bacterium sequesters iron in the ferrous state (FeII); therefore, not requiring siderophores. Instead an energy efficient process involving upregulation of large porins is employed concomitantly with genes associated with biofilm formation. We hypothesise that rock weathering is induced by changes in chemical equilibrium at the microbe-mineral interface, reducing the saturation state of iron. We also demonstrate that low concentrations of metals in the basalt induce heavy metal resistant genes. Volcanic environments are analogous to some of the earliest environments on Earth. These results not only elucidate the mechanisms by which microorganisms might have sequestered nutrients on the early Earth but they also provide an explanation for the evolution of multiple heavy metal resistance genes long before the creation of contaminated industrial biotopes by human activity.
Project description:In this study, we isolated and characterized rock-weathering bacteria from the surfaces of less and more altered tuffs, along with the adjacent soils, with respect to their rock weathering pattern, stress resistance, community structure, and the changes in these rocks and soils. Using a moderate-nutrition medium, we obtained 150 isolates from the rocks and soils. The rock-weathering patterns of the isolates were characterized using batch cultures that measure the quantity of Si, Al, and Fe released from tuff under aerobic conditions. Based on the potential of the bacterial influence on the element releases, the isolates could be grouped into highly, moderately, and least effective element solubilizers, respectively. Significantly more highly effective Al and Fe solubilizers were observed in the altered rocks, while the soils had more highly effective Si solubilizers. Furthermore, more isolates from the altered rocks significantly acidified the culture medium in the rock weathering process. Dynamic changes in the element release showed the distinct element releasing patterns of three selected isolates. More isolates from the altered rocks could grow at 4 °C or at 55 °C or at pH 4. Some isolates from the altered rocks could grow at pH 10 and with 10-15% (w/v) NaCl. The altered rocks and the soils existed in diverse and different highly weathering-specific culturable rock-weathering community structures. The changes in the culturable weathering communities between the altered rocks and the soils were attributable not only to major bacterial groups but also to a change in the minor population structure.
Project description:The weathering of volcanic minerals makes a significant contribution to the global silicate weathering budget, influencing carbon dioxide drawdown and climate control. Basalt rocks may account for over 30% of the global carbon dioxide drawdown in silicate weathering. Yet the genetics of biological rock weathering are unknown. For the first time, we apply a DNA microarray to investigate the genes involved in weathering by the heavy metal resistant organism, Cupriavidus metallidurans CH34; in particular we investigate the sequestering of iron. The results show that the bacterium sequesters iron in the ferrous state (FeII); therefore, not requiring siderophores. Instead an energy efficient process involving upregulation of large porins is employed concomitantly with genes associated with biofilm formation. We hypothesise that rock weathering is induced by changes in chemical equilibrium at the microbe-mineral interface, reducing the saturation state of iron. We also demonstrate that low concentrations of metals in the basalt induce heavy metal resistant genes. Volcanic environments are analogous to some of the earliest environments on Earth. These results not only elucidate the mechanisms by which microorganisms might have sequestered nutrients on the early Earth but they also provide an explanation for the evolution of multiple heavy metal resistance genes long before the creation of contaminated industrial biotopes by human activity. Cultures of Cupriavidus metallidurans CH34 were grown in Tris buffered medium MM284 media (with iron), MM284 without iron and MM284 without iron with sterilized basalt at 25 rpm, 30°C until mid-log phase. RNA was extracted from the cells. Three biological replicates of both samples were differentially labeled (resp. Cy3 and Cy5) and hybridized to three CH34 60-mer oligonucleotide glass-spotted microarray carrying three technical repeats.
Project description:Deep sequencing of mRNA from the rock pigeon Analysis of ploy(A)+ RNA of different specimens: heart and liver from the rock pigeon (Danish Tumbler, Oriental Frill and Racing)