This review explores eco-friendly methods for extracting bioactive natural products from diverse sources. The introductory exploration emphasizes the increasing demand for sustainable extraction methods, with a focus on the environmental impact of conventional approaches. Addressing existing knowledge gaps, this review outlines the key objectives of evaluating various green extraction technologies, including supercritical fluid extraction, pressurized liquid extraction, ultrasound-assisted extraction, enzyme-assisted extraction, and others. The primary findings underscore the remarkable potential and advancements achieved with green solvents, specifically deep eutectic solvents and bio-based solvents. This review elucidates the synergistic effects achieved by combining different extraction techniques, exemplified by ultrasound-microwave-assisted extraction and sequential supercritical fluid and pressurized liquid extraction, among others. Notwithstanding the promising results, this review emphasizes the importance of acknowledging and addressing challenges such as standardization, selectivity, scalability, and economic viability.

Hydrothermal systems, including terrestrial hot springs, contain diverse geochemical conditions that vary over short spatial scales due to progressive interaction between the reducing hydrothermal fluids, the oxygenated atmosphere, and in some cases seawater. At Jinata Onsen, on Shikinejima Island, Japan, an intertidal, anoxic, iron-rich hot spring mixes with the oxygenated atmosphere and seawater over short spatial scales, creating a diversity of chemical potentials and redox pairs over a distance ~10 m. We characterized the geochemical conditions along the outflow of Jinata Onsen as well as the microbial communities present in biofilms, mats, and mineral crusts along its traverse via 16S rDNA amplicon and genome-resolved shotgun metagenomic sequencing. The microbial community changed significantly downstream as temperatures and dissolved iron concentrations decreased and dissolved oxygen increased. Near the spring source, biomass is limited relative to downstream, and primary productivity may be fueled by oxidation of ferrous iron and molecular hydrogen by members of the Zetaproteobacteria and Aquificae. Downstream, the microbial community is dominated by oxygenic Cyanobacteria. Cyanobacteria are abundant and active even at ferrous iron concentrations of ~150 μM, which challenges the idea that iron toxicity limited cyanobacterial expansion in Precambrian oceans. Several novel lineages of Bacteria are also present at Jinata Onsen, including previously uncharacterized members of the Chloroflexi and Caldithrichaeota phyla, positioning Jinata Onsen as a valuable site for future characterization of these clades. Importance: High temperatures and reducing conditions allow hot springs to support microbial communities that are very different from those found elsewhere on the surface of the Earth today; in some ways, these environments and the communities they support can be similar to environments that existed on the early Earth and that may exist on other planets. Here, we describe a novel hot spring system where hot, iron-rich but oxygen-poor water flows into the ocean, supporting a range of unique microbial communities. Metagenomic sequencing recovered many novel microbial lineages, including deep-branching and uniquely thermotolerant members of known groups. Comparison of the biological communities in the upstream part of the hot spring, potentially supported by biological iron and hydrogen oxidizing metabolisms, to downstream microbial mats, supported by oxygenic photosynthesis, provides insight into the potential productivity of life during Proterozoic time and on other planets where oxygenic photosynthesis is not possible.