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Scalable and Consolidated Microbial Platform for Rare Earth Element Leaching and Recovery from Waste Sources
Not Available
Microbial Proxies for Anoxic Microsites Vary with Management and Partially Explain Soil Carbon Concentration
Anoxic microsites are potentially important but unresolved contributors to soil organic carbon (C) storage. How anoxic microsites vary with soil management and the degree to which anoxic microsites contribute to soil C stabilization remain unknown. Sampling from four long-term agricultural experiments in the central United States, we examined how anoxic microsites varied with management (e.g., cultivation, tillage, and manure amendments) and whether anoxic microsites determine soil C concentration in surface (0–15 cm) soils. We used a novel approach to track anaerobe habitat space and, hence, anoxic microsites using DNA copies of anaerobic functional genes over a confined volume of soil. No-till practices inconsistently increased anoxic microsite extent compared to conventionally tilled soils, and within one site organic matter amendments increased anaerobe abundance in no-till soils. Across all long-term tillage trials, uncultivated soils had ~2–4 times more copies of anaerobic functional genes than their cropland counterparts. Finally, anaerobe abundance was positively correlated to soil C concentration. Even when accounting for other soil C protection mechanisms, anaerobe abundance, our proxy for anoxic microsites, explained 41% of the variance and 5% of the unique variance in soil C concentration in cropland soils, making anoxic microsites the strongest management-responsive predictor of soil C concentration. Our results suggest that careful management of anoxic microsites may be a promising strategy to increase soil C storage within agricultural soils.
The Mobility of Mo during Microbially Mediated Ferrihydrite Phase Transformation
Molybdenum (Mo) is an essential nutrient for almost all organisms. However, at high concentrations, it can be toxic to animals and plants. This study investigated the interactions of Mo(VI) with iron oxyhydroxides during ferrihydrite bioreduction in the presence of the Fe(III)- reducing Geobacter sulfurreducens. Here, in this study, we showed that Mo concentration controlled ferrihydrite phase transformation, leading to Mo release. With the biotic reduction of ferrihydrite and Fe(II) production, Mo(VI) reduction and Mo(IV)O 2 formation were observed for the first time, which further immobilised Mo after surface adsorption of Mo(VI). At low Mo levels (Mo/Fe molar ratios of 1-2 %), sufficient Fe(II) adsorption onto ferrihydrite resulted in its transformation into magnetite nanoparticles (>80%, ~25 nm) which catalysed the reduction of Mo(VI) to form Mo(IV)O 2 and immobilised Mo. Contrastingly, at high Mo concentrations (Mo/Fe molar ratios of 5-10%), Mo(VI)O 4 2- adsorption onto ferrihydrite limited Fe(II) adsorption, subsequently less magnetite (<8-12%) formed while more goethite (~30- 50%, width & length > 15 & 100 nm, respectively) and siderite (~20-30%, width & length > 100 & 200 nm, respectively) with larger particle sizes formed instead, causing Mo(VI) release due to lower Mo adsorption. This study provides a comprehensive understanding of the interaction mechanisms among Geobacter sulfurreducens, Mo(VI), and iron oxyhydroxides, enabling predictions and controls of long-term Mo mobility and Fe mineral transformation under a variety of biogeochemical scenarios.
Bioelectronic Platform to Investigate Charge Transfer between Photoexcited Quantum Dots and Microbial Outer Membranes
Not provided.
Biosynthesis of Haloterpenoids in Red Algae via Microbial-like Type I Terpene Synthases
Red algae or seaweeds produce highly distinctive halogenated terpenoid compounds, including the pentabromochlorinated monoterpene halomon that was once heralded as a promising anticancer agent. The first dedicated step in the biosynthesis of these natural product molecules is expected to be catalyzed by terpene synthase (TS) enzymes. Recent work has demonstrated an emerging class of type I TSs in red algal terpene biosynthesis. However, only one such enzyme from a notoriously haloterpenoid-producing red alga (Laurencia pacifica) has been functionally characterized and the product structure is not related to halogenated terpenoids. Herein, we report 10 new type I TSs from the red algae Portieria hornemannii, Plocamium pacificum, L. pacifica, and Laurencia subopposita that produce a diversity of halogenated mono- and sesquiterpenes. Here we used a combination of genome sequencing, terpenoid metabolomics, in vitro biochemistry, and bioinformatics to establish red algal TSs in all four species, including those associated with the selective production of key halogenated terpene precursors myrcene, trans-β-ocimene, and germacrene D-4-ol. These results expand on a small but growing number of characterized red algal TSs and offer insight into the biosynthesis of iconic halogenated algal compounds that are not without precedence elsewhere in biology.
Discovering the Microbial Enzymes Driving Drug Toxicity with Activity-Based Protein Profiling
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Microbially Synthesized Polymeric Amyloid Fiber Promotes [beta]-Nanocrystal Formation and Displays G
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Microbial Carbonation of Monocalcium Silicate
Not Available
Photothermal Properties of Nanostructured Black Titanium Dioxide for Targeted Cellular and Microbial Elimination
Heterophase black titanium dioxide (hB-TiO 2 ), characterized by broadened near-infrared (NIR) absorption, has emerged as a promising photothermally active nanomaterial. This study focused on the synthesis of nanoscale hB-TiO 2 and its evaluation as a multifunctional agent for photothermal therapy (PTT). The purity and composition of the mixed-phase nanoscale hB-TiO 2 were demonstrated by X-ray diffraction, and the morphology of nanoparticles was imaged by transmission electron microscopy. Extensive additional characterization was conducted to validate the optoelectronic properties. The material was further evaluated in biological systems using NIH 3T3-GFP fibroblasts and the fungus Candida albicans. Nanoscale hB-TiO 2 exhibited good biocompatibility in the absence of laser irradiation and effectively ablated both NIH 3T3-GFP cells and C. albicans following 20 min of laser exposure. This noninvasive treatment strategy leverages NIR-responsive materials to induce localized hyperthermia. The findings provide grounds for the use of selectively induced hyperthermia, which could be employed for the targeted destruction of cells or fungi with minimal impact on surrounding tissue if the material is functionalized with specific targeting groups and delivered to cells or fungal infections.
Impact of Drought Stress on Sorghum bicolor Yield, Deconstruction, and Microbial Conversion Determined in a Feedstocks-to-Fuels Pipeline
Sorghum is an attractive feedstock for biobased fuel and chemical production because it is familiar to farmers, naturally drought tolerant, and versatile as a food, feed, and fuel crop. Although sorghum is a promising feedstock, particularly in regions that experience drought stress, little is known about how drought conditions impact the ease of conversion of sorghum to fuels and products. This study combines agronomic field trials with a high-throughput experimental pipeline to explore the field performance and liquid biofuel (bisabolene) yields resulting from three sorghum types (photosensitive forage sorghum, optimized grain sorghum, and drought-resistant grain sorghum) grown under pre- and postflowering water limitations in two different California locations. Multiple drought treatments are compared to the control, as the timing (preflowering versus postflowering) of drought stress elicits different survival strategies and corresponding impacts on yield and composition. Forage-type sorghum maintained the highest biomass yields across all irrigation conditions and locations. Glucose and xylose yields resulting from ionic liquid pretreatment and enzymatic saccharification were not significantly impacted by irrigation treatments but differed by location and genotype. However, Rhodosporidium toruloides grown on the resulting plant hydrolysates unexpectedly produced higher titers of bisabolene for drought-stressed sorghum samples regardless of genotype.
Smart Microbial Cells Couple Catalysis and Sensing to Provide High-Throughput Selection of an Organophosphate Hydrolase
Enzyme engineering for gain of function requires navigating a large combinatorial sequence space efficiently. Typically, many mutations are needed to get significant improvements, while a single “bad” mutation can inactivate the enzyme. To establish high-throughput screening and achieve enhanced resolution between two variants, genetic libraries of the organophosphate hydrolase enzyme paraoxonase 1 (PON 1 ) were rapidly screened via an engineered positive-feedback circuit: a p-nitrophenol (PNP)-specific transcription factor (TF) regulated expression of PON 1 , which catalyzed paraoxon breakdown and PNP production. Rare active mutant colonies, picked by simple visual fluorescence of a PON 1 –green fluorescent protein (GFP) fusion, were characterized. Furthermore, in a single screening round, high (library-scale) throughput enabled the discovery of enhanced paraoxon degradation activity in PON 1 , including structurally unexpected mutations.
Optogenetic Control of Microbial Consortia Populations for Chemical Production
Not provided.