Project description:The aim of this research was to isolate purple bacteria from waste that degrade plastics. Using metagenomic techniques, bacteria living in plastic debris were identified, and subsequently the metabolic pathways and proteins involved in them were studied using metaproteomics.
Project description:The aim of this research was to isolate purple bacteria from waste that degrade plastics. Using metagenomic techniques, bacteria living in plastic debris were identified, and subsequently the metabolic pathways and proteins involved in them were studied using metaproteomics.
Project description:The circular bioeconomy has become a crucial strategy for sustainable development, especially by upcycling organic-rich by-products from various industrial processes. Purple non-sulphur bacteria (PNSB) have emerged as excellent candidates in this field, demonstrating exceptional metabolic versatility. While the growth of PNSB on sugar-rich streams has been extensively explored, the sugar assimilation metabolism remains poorly understood. Here, we explore the metabolic mechanisms of sucrose utilisation in two phototrophic purple non-sulphur bacteria (PNSB), Rhodospirillum rubrum and Rhodobacter capsulatus. Our findings demonstrate distinct carbohydrate hydrolysis and assimilation capacities, as well as the use of different redox strategies for each species. Moreover, Rhodospirillum rubrum could only grow on sucrose when co-cultivated with Rhodobacter capsulatus. This trophic link between Rhodospirillum rubrum and Rhodobacter capsulatus in sucrose containing co-culture was characterised and resulted in significantly enhanced productivity compared to pure cultures. Finally, we demonstrate that the synergy observed between Rhodospirillum rubrum and Rhodobacter capsulatus can be successfully scaled up in a photobioreactor system. Our study highlights how fundamental knowledge of the metabolism, trophic link and general microbial ecology concept might be useful for the development of biobased resource recovery strategies.
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.