Transition metals, including iron, zinc, copper, manganese, cobalt, nickel, and molybdenum, are vital micronutrients for microorganisms because they act as essential cofactors and structural component...

Transition metals, including iron, zinc, copper, manganese, cobalt, nickel, and molybdenum, are vital micronutrients for microorganisms because they act as essential cofactors and structural components of enzymes involved in diverse cellular processes (1, 2). Among these metals, iron is most significant because of its redox flexibility between the ferrous (Fe²+) and ferric (Fe³+) forms, which allows it to participate in essential processes such as electron transfer, cellular respiration, nitrogen fixation, DNA metabolism, and antioxidant defense (3–5). Given its central role in important cellular processes, iron is required by almost all organisms, with only a few notable exceptions such as Lactobacillus spp (6) and Borrelia burgdorferi (7). Although iron is plentiful in the Earth’s crust, its bioavailability is far below the cellular requirements because soluble ferrous iron is rapidly oxidized to insoluble ferric hydroxides at physiological pH and oxygenated conditions. In addition, pathogenic microorganisms face further iron limitation in the host, where iron is tightly sequestered by the host immune proteins like transferrin and lactoferrin, thereby restricting microbial access to this important micronutrient (4, 8).

Partial denitrification stabilized mainstream single-stage partial nitrification/anammox by converting excess nitrate to nitrite for anammox and increasing heterotrophic oxygen consumption. Maintaini...

Communities of heterotrophic particle-associated marine bacteria contribute to oceanic carbon cycling through interspecies interactions that can influence polysaccharide degradation. While these interactions have been extensively studied using single natural isolates or pairwise combinations thereof, their mechanistic relevance within multispecies communities remains unclear. To address this gap, we developed MCC4, a minimal chitin-degrading bacterial community consisting of two chitin degraders and two non-degrading isolates that represent globally prevalent marine bacterial taxa. We show that the community remains stable across ten growth-dilution cycles, establishing a reproducible model for controlled multi-isolate experiments. Using transcriptomic and metabolomic analyses combined with metabolite supplementation assays, we uncovered the underlying crossfeeding network. While one degrader drives chitin degradation, the other exploits chitin monomers and chitooligomers generated by the main degrader. The two non-degraders are sustained by consuming deacetylated chitin monomers, 2-carbon compounds, nucleotides, and branched-chain amino acids, likely released by degraders. Community assembly is driven by competitive scavenging abilities, potentially complemented by specific survival strategies such as increased motility and deployment of type VI secretion systems. Despite its simplicity, MCC4 captures dynamic microbial interactions characteristic of natural marine ecosystems. It offers a tractable, reproducible framework for investigating how environmental perturbations impact community function and testing ecological theories in particle-associated marine environments. ### Competing Interest Statement The authors have declared no competing interest. Simons Foundation, 542395

Abstract. Dark-heterotrophic growth allows photosynthetic pigment–protein complexes to be examined when photosynthetic energy conversion is not required fo

Abstract. Engineered cyanobacteria offer a sustainable platform for the conversion of light and CO2 into value-added chemicals. Unlike heterotrophic system

We explored the ability of C. reinhardtii to modulate the pH of its surrounding environment. Under light conditions, carbon fixation and nitrogen assimilation are expected to elevate ambient pH, while in the dark, respiration should reduce it. To allow larger pH variations in the culture, we removed the Tris buffering component from the traditional Tris-acetate-phosphate (TAP) growth medium. Additionally, acetate was excluded to prevent heterotrophic carbon metabolism by the algal cells, and finally, the nitrogen source was changed from NH4Cl to NaNO323. Microalgal cells were cultured in this NaNO3-minimal medium under 6-h light/18-h darkness cycles, and reversible pH fluctuations were shown to persist over at least 14 cycles (Fig. 2a), with a progressive elevation in both upper and lower limits over successive cycles. A closer look at a representative pH fluctuation curve (Fig. 2b) reveals a rapid pH increase from 8.1 to 10.8 within the first 2.7 h of illumination, followed by a gradual approach to a plateau at pH 11.0 for the remaining 3.3 h under light. Upon transition to darkness, the pH decreased until it reached 8.1 after 18 h. The biological processes underlying the pH changes are described in Fig. 2c and Supplementary Fig. 2. First, for...

Biogenic volatile organic compounds (BVOCs) emissions from 16 heterotrophic bacterial strains cultivated from Baltic Sea surface waters were quantified using PTR-ToF-MS. Strains showed broadly overla...

Photosymbiosis, the partnership between heterotrophic hosts and phototrophic symbionts, is a cornerstone of evolutionary innovation that sustains biodiversity from tropical coral reefs to temperate lakes. Despite their evolutionary success, these associations are surprisingly susceptible to anthropogenic change. By developing a universal population growth model, we demonstrate that the very metabolic interactions that sustain their immense productivity also create an inherent sensitivity to anthropogenic stress. We show that the competition for essential nutrients within the partnership makes the most productive symbioses the most vulnerable to breakdown. This work provides a mechanistic framework to predict how global change threatens the stability of these vital ecological cornerstones, offering a new lens through which to understand and mitigate symbiotic collapse.

Heterotrophic microorganisms are abundant across ecosystems and play a central role in environmental carbon cycling by storing, transforming, and decomposing organic matter. However, heterotrophs can ...

Abstract. In plants, the directed distribution of photosynthetic products from source organs to heterotrophic sink organs forms the material basis for biom

Read the full paper: Identification of genetic determinants that promote biofilm growth under heterotrophic conditions in Cupriavidus necator using transposon enrichment

Premise The inclusion of heterotrophic plants in broader systematic studies is challenging due to substantial morphological modification, gene loss, and accelerated substitution rates following phot...

Read the full paper: Weaving Life Into Regolith: Synthetic Autotrophic–Heterotrophic Consortia for Autonomous Biofabrication From Granular Feedstocks