Project description:Relentless mining operations have destroyed our environment significantly. Soil inhabiting microbes play a significant role in ecological restoration of these areas. Microbial weathering processes like chemical dissolution of rocks significantly promotes the soil properties and enhances the rock to soil ratio respectively. Earlier studies have reported that bacteria exhibit efficient rock-dissolution abilities by releasing organic acids and other chemical elements from the silicate rocks. However, rock-dissolving mechanisms of the bacterium remain to be unclear till date. Thus, we have performed rock-dissolution experiments followed by genome and transcriptome sequencing of novel Pseudomonas sp.NLX-4 strain to explore the efficiency of microbe-mediated habitat restoration and its molecular mechanisms underlying this biological process. Results obtained from initial rock dissolution experiments revealed that Pseudomonas sp. NLX-4 strain efficiently accelerates the dissolution of silicate rocks by secreting amino acids, exopolysaccharides, and organic acids with elevated concentrations of potassium, silicon and aluminium elements. The rock dissolution experiments of NLX-4 strain exhibited an initial increase in particle diameter variation values between 0-15 days and decline after 15 days-time respectively. The 6,771,445-base pair NLX-4 genome exhibited 63.21 GC percentage respectively with a total of 6041 protein coding genes. Genome wide annotations of NLX-4 strain exhibits 5045-COG, 3996-GO, 5342-InterPro, 4386-KEGG proteins respectively Transcriptome analysis of NLX-4 cultured with/without silicate rocks resulted in 539 (288-up and 251-down) differentially expressed genes (DEGs). Fifteen DEGs encoding for siderophore transport, EPS and amino acids synthesis, organic acids metabolism, and bacterial resistance to adverse environmental conditions were highly up-regulated by cultured with silicate rocks. This study has not only provided a new strategy for the ecological restoration of rock mining areas, but also enriched the applicable bacterial and genetic resources.
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.