Atmospheric dust gives plants nutrients through their leaves, study finds

Research in New Phytologist shows that plants can acquire nutrients not only from the soil but also from atmospheric dust that settles and dissolves on their leaves, releasing elements such as phosphorus and iron.

In a Mediterranean field study simulating dust events, dust application increased plant macronutrient and micronutrient concentrations through the plants' mildly acidic leaves. By integrating field observations with dust-deposition estimates and soil nutrient data from different regions, investigators found that during dust events, daily nutrient inputs via foliar uptake can match or exceed soil-derived inputs.

"This suggests a shift from the traditionally soil-centric view of nutrient acquisition toward a vegetation-mediated pathway, where the plant canopy acts as an active interface for capturing and processing atmospheric particles," said Anton Lokshin, a postdoctoral researcher at Ben-Gurion University of the Negev, Israel.

 "In nutrient-limited ecosystems, this leaf-based nutrient pathway may represent an important and currently overlooked contribution to plant nutrition and ecosystem functioning." The study was conducted by Anton Lokshin in the laboratory of Dr. Avner Gross, in collaboration with Dr. Daniel Palchan (Ariel University) Prof. Marcelo Sternberg (Tel Aviv University), Tom Goren (Bar Ilan university), and Andre (Mahdi) Nakhavali (IIASA).

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Stopping algae blooms with bacteria-busting buoys

Algae blooms make a pond's surface shine in mesmerizing green hues. But if the microorganisms responsible are cyanobacteria, they can also release toxins that harm humans and wildlife alike. A team reporting in ACS ES&T Water has designed a "set it and forget it" system for distributing algaecide using specialized buoys tethered at the site of a bloom. In tests, the buoys removed nearly all cyanobacteria without the need for frequent reapplication.

Algae blooms occur when extra nutrients in the water—likely from fertilizer runoff—cause tiny microorganisms like algae and cyanobacteria to proliferate.

In 2014, one such algae bloom in Lake Erie near Toledo, Ohio, rendered drinking water unsafe for hundreds of thousands of residents. Now, a team of researchers from the University of Toledo seeks to create an algaecide treatment system that puts a stop to a bloom before it has even started.

 The team, including Umberto Kober, Hanieh Barikbin, Youngwoo Seo, Yakov Lapitsky and colleagues, designed a system that releases algaecide steadily over a period of weeks or months, making it less expensive and more efficient than existing options that require frequent reapplication.

 The team constructed small, medium, and large-sized buoys out of PVC pipes, forming either a "T" or cross shape. Hydrogel disks were inserted into the pipe openings to control the diffusion of the liquid algaecide into the surrounding water. The buoys were then filled with a commercial hydrogen peroxide-based algaecide, which, upon immersion, slowly diffused through the hydrogel disks. The buoys were also engineered so that once the algaecide was gone, the buoy fell to its side, visually indicating that a refill was needed.

To test their performance, the small, algaecide-loaded buoys were put in a beaker with one liter of cyanobacteria-containing water collected from Lake Erie and monitored for two weeks. Every day a small portion of water was replaced with new lake water to ensure the buoys were continually exposed to fresh cyanobacteria. This way, the team could evaluate whether the buoys provided sustained algicidal activity rather than killing the cyanobacteria early in the process. Researchers found that the cyanobacteria were almost entirely eliminated within a week, and other microbes remained largely unscathed. Researchers estimate that their buoys could reliably release algaecide for at least four consecutive release cycles, each lasting 35 days.

Though further research is needed, including enhancements to prevent microbe growth on the buoy's surface, the researchers say that this work overcomes challenges in sustained and targeted algaecide treatment.

"If successfully scaled up, this concept could enable early mitigation of harmful algal blooms without the need for labor-intensive repeated algaecide applications," says Lapitsky.

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Study reveals mechanisms underlying oxygen-tolerant energy conversion in a marine photosynthetic bacterium

Photosynthetic bacteria do not release oxygen during photosynthesis but can convert solar energy into chemical energy with remarkably high efficiency. They also utilize near-infrared light—wavelengths unused by plants—and thrive in diverse environments, including freshwater, seawater, and hot springs.

Among these organisms, the marine purple nonsulfur bacterium Rhodovulum sulfidophilum is a model species notable for its strong tolerance to oxygen. However, the molecular mechanism by which its light-harvesting and energy-converting LH1-RC complex maintains highly efficient photosynthesis under oxic conditions remains unclear.

Researchers at University of Tsukuba used cryo-electron microscopy to visualize the structure of the protein complex responsible for photosynthesis in Rhodovulum sulfidophilum. Their analysis uncovered a previously unrecognized membrane protein and revealed structural features that could explain how this organism achieves efficient energy conversion despite the presence of oxygen.

In their study published in Communications Biology, the researchers determined the structure of the LH1-RC complex at an exceptionally high resolution of 1.8 Å using cryo-EM. Their analysis identified a previously unknown membrane protein called protein-3h, which is located within the LH1 opening. They further discovered a non-heme Fe ion positioned near the triheme cytochrome subunit, which is coordinated by a histidine residue and water molecules rather than by heme. This configuration indicates that the Fe ion might act as an intermediary site for electron transfer.

These findings provide deeper insight into the photosynthetic complex in R. sulfidophilum and could contribute to future applications, such as genetically engineered phototrophic systems and environmentally relevant technologies, including the bioremediation of hydrogen sulfide-containing wastewater.

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