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ABSTRACT Efforts toward microbial conversion of lignin to value-added products face many challenges because lignin’s methoxylated aromatic monomers release toxic C₁byproducts such as formaldehyde. The ability to grow on methoxylated aromatic acids (e.g., vanillic acid) has been identified in certain clades of methylotrophs, bacteria characterized by their unique ability to tolerate and metabolize high concentrations of formaldehyde. Here, we use a phyllosphere methylotroph isolate,Methylobacterium extorquensSLI 505, as a model to identify the fate of formaldehyde during methylotrophic growth on vanillic acid.M. extorquensSLI 505 displays concentration-dependent growth phenotypes on vanillic acid without concomitant formaldehyde accumulation. We conclude thatM. extorquensSLI 505 overcomes metabolic bottlenecks from simultaneous assimilation of multicarbon and C₁intermediates by allocating formaldehyde toward dissimilation and assimilating the ring carbons of vanillic acid heterotrophically. We correlate this strategy with maximization of bioenergetic yields and demonstrate that formaldehyde dissimilation for energy generation rather than formaldehyde detoxification is advantageous for growth on aromatic acids.M. extorquensSLI 505 also exhibits catabolite repression during growth on methanol and low concentrations of vanillic acid, but no diauxic patterns during growth on methanol and high concentrations of vanillic acid. Results from this study outline metabolic strategies employed byM. extorquensSLI 505 for growth on a complex single substrate that generates both C₁and multicarbon intermediates and emphasizes the robustness ofM. extorquensfor biotechnological applications for lignin valorization.IMPORTANCELignin, one of the most abundant and renewable carbon sources on Earth, is a promising alternative to non-renewable fossil fuels used to produce petrochemicals. Degradation of lignin releases toxic C₁byproducts such as formaldehyde, and thus most microorganisms are not suitable for biorefining lignin. By contrast,Methylobacterium extorquensSLI 505 is capable of growth on high concentrations of aromatic acids without concomitant formaldehyde accumulation. In addition, we show that the growth ofM. extorquensSLI 505 on aromatic acids is coupled to the production of the bioplastic, polyhydroxybutyrate. Aromatic acids serve as a model by which to understand howM. extorquensSLI 505 balances methylotrophic and heterotrophic pathways during growth to provide strategies for growth optimization when using complex substrates in both ecological and industrial fermentation applications. 

Abstract Several hundreds of tons of gadolinium‐based contrast agents (GBCAs) are being dumped into the environment every year. Although macrocyclic GBCAs exhibit superior stability compared to their linear counterparts, we have found that the structural integrity of chelates is susceptible to ultraviolet light, regardless of configuration. In this study, we present a synthetic protein termed GLamouR that binds and reports gadolinium in an intensiometric manner. We then explore the extraction of gadolinium from MRI patient urine as a preventative measure for gadolinium pollution and investigate the viability of employing cost‐effective bioremediation techniques for treating contaminated water bodies. Based on promising results, we anticipate proteins such as GLamouR can be used for detecting and mining rare earth elements beyond gadolinium and hope to expand the biological toolbox for such applications. 

Many bacteria secrete metallophores, low-molecular-weight organic compounds that bind ions with high selectivity and affinity, in order to access essential metals from the environment. Previous work has elucidated the structures and biosynthetic machinery of metallophores specific for iron, zinc, nickel, molybdenum, and copper. No physiologically relevant lanthanide-binding metallophore has been discovered despite the knowledge that lanthanide metals (Ln) have been revealed to be essential cofactors for certain alcohol dehydrogenases across a diverse range of phyla. Here, we report the biosynthetic machinery, the structure, and the physiological relevance of a lanthanophore, methylolanthanin. The structure of methylolanthanin exhibits a unique 4-hydroxybenzoate moiety which has not previously been described in other metallophores. We find that production of methylolanthanin is required for normal levels of Ln accumulation in the methylotrophic bacterium Methylobacterium extorquens AM1, while overexpression of the molecule greatly increases bioaccumulation and adsorption. Our results provide a clearer understanding of how Ln-utilizing bacteria sense, scavenge, and store Ln; essential processes in the environment where Ln are poorly bioavailable. More broadly, the identification of this lanthanophore opens doors for study of how biosynthetic gene clusters are repurposed for additional functions and the complex relationship between metal homeostasis and fitness. 

ABSTRACT Methylothon is an inquiry-based high school learning module in microbial ecology, molecular biology, and bioinformatics that centers around pink-pigmented plant-associated methylotrophic bacteria. Here, we present an overview of the module’s learning goals, describe course resources (available for public use at http://methylothon.com ), and relate lessons learned from adapting Methylothon for remote learning during the pandemic in spring of 2021. This curriculum description is intended not only for instructors but also for microbial ecology researchers with an interest in conducting K-12 outreach. The original in-person version of the module allows students to isolate their own strains of methylotrophic bacteria from plants they sample from the environment, to identify these using PCR, sequencing, and phylogenetic analysis, and to contribute their strains to original research in a university lab. The adapted version strengthens the focus on bioinformatics and increases its flexibility and accessibility by making the lab portion optional and adopting free web-based tools. Student feedback and graded assignments from spring 2021 revealed that the lesson was especially effective at introducing the concepts of BLAST and phylogenetic trees and that students valued and felt inspired by the opportunity to conduct hands-on work and to participate in community science.