Microbe-Metal-Mineral Interactions

Overview

Nutrient management is essential for the cultivation of algae and crops used for food and biofuels. In seawater and much of the world's farmable lands, providing crops with adequate nutrition is challenging because high salt and pH levels, which reduces the solubility of trace metals (such as Fe) and phosphate. While frequent application of chemical fertilizers can alleviate nutrient limitation, chelated iron fertilizers are expensive and impractical on large scales, and reserves of phosphatic rocks are limited and will be depleted within several hundred years at current mining rates. One promising sustainable solution is the enhancement of microbial processes for dissolving mineral forms of these nutrients. Our research seeks to elucidate host-microbiome interactions that can increase the bioavailability of essential nutrients and metals in order to design rational strategies for improving growth and sustainability.

How do siderophores produced by fungi enhance nutrient uptake of switchgrass?

Participant: Ikumi Ellis

Switchgrass is a leading candidate for renewable biofuel production, but its long-term sustainability depends on reducing fertilizer inputs like nitrogen, phosphorus, and iron. Our research explores how root-associated fungi help switchgrass access iron through the secretion of specialized molecules called siderophores. Different fungal strains produce distinct siderophores, some of which significantly boost iron levels in plant shoots. By identifying and characterizing these compounds, we aim to uncover how fungal partnerships can enhance nutrient uptake naturally. This work helps guide the selection of beneficial microbes to reduce chemical inputs and improve the environmental footprint of biofuel agriculture.

Pictures from Ikumi: fungi and switchgrass!

Phototroph-heterotroph interactions for mining metals

Participant: Nicole Coffey

Metal mobilization from soil minerals is critical for plant and phytoplankton growth, particularly in ocean gyres away from continental sources of iron or marginal lands with high pH soils. However, the specific mechanisms that liberate metals from these minerals and the organisms involved remain largely unknown. To address this knowledge gap, our research investigates how microbial communities acquire essential metals from minerals like dust. We focus on identifying the keystone organisms and metabolic pathways that control the bioavailability of micronutrients such as iron, which are critical for regulating ecosystem growth. By combining advanced chemical analyses with multi-omics and incubation studies, we have shown that symbiotic interactions between photosynthetic organisms (such as marine diatom Phaeodactylum tricornutum) and their microbiome play a crucial role in metal solubilization and uptake. Understanding these microbial partnerships provides fundamental insight into the interactions that drive the ocean’s carbon, nitrogen, and metal cycles.

Mineral-associated organic matter formation and transformations

Participant: Alek Rabago, Austin Tinkey, Anil Timilsina

Mineral-associated organic matter (MAOC) is an important terrestrial carbon sink, though its biological sources and mechanisms of formation are not fully understood. Lignin is a heterogeneous biopolymer that comprises up to 60% of plant woody tissue and is the largest terrestrial source of aromatic carbon. It is broken down in soils to small molecule products by soil bacteria and fungi, and these products strongly resemble MAOC in composition. This project aims to understand the processes behind MAOC formation by examining adsorption capacities of lignin degradation products to soil minerals. This is a collaborative project with the Yang group at UNevada Reno and Penn group at UMN.

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