Growth Promotion of Chlamydomonas reinhardtii by Cupriavidus oxalaticus MEYA8

Exploring the synergistic effect of Pseudomonas monteilii on the growth promotion of mangrove isolated cyanobacterium Leptolyngbya lignicola

Orsellinic Acid from the Endophytic Fusarium oxysporum Drives Specialized Metabolism in Peperomia obtusifolia

The metabolic cooperation between plants and their endophytic fungi represents a promising frontier in the biosynthesis of natural products. This study elucidates the contribution of the endophytic fungus Fusarium oxysporum Po18 to the production of aromatic polyketides that drive specialized metabolism in Peperomia obtusifolia. Cultivation parameters for F. oxysporum were optimized using a Central Composite Rotatable Design (CCRD), revealing that mild temperatures (28 °C) and extended incubation (9 days) maximized orsellinic acid accumulation. LC–MS/MS identified orsellinic acid as [M–H]– at m/z 167.0356, with the diagnostic fragment ion m/z 122.8924, and quantified by HPLC–DAD, achieving a concentration of 132 μg/mL under optimized conditions. Comparative metabolomic analysis and molecular networking (GNPS) revealed related fungal metabolites, including lecanoric acid, 6-methylsalicylic acid, and citrinin, all derived from the fungal polyketide synthase (PKS) pathway. These metabolites are proposed to act as biosynthetic precursors for chroman and benzopyran derivatives previously reported in P. obtusifolia. The results provide the first experimental evidence of a biosynthetic partnership between Fusarium and Peperomia, in which the endophyte may supply aromatic scaffolds that could subsequently undergo downstream modifications in the host plant. This study expands the understanding of fungal–plant metabolic interactions and highlights F. oxysporum as a sustainable biotechnological source of aromatic polyketides with potential applications in natural product chemistry and biocatalysis.

Proteomic responses of Phaeocystis globosa during colony development promoted by Skeletonema costatum culture filtrate.

Phaeocystis globosa has a polymorphic life cycle characterized by the alternation between free-living solitary cells and a colonial morphotype. Colony formation is pivotal to the initiation and development of Phaeocystis blooms, which in marine ecosystems often occur after diatom blooms. To investigate the relationship between diatoms and P. globosa colony formation, we exposed solitary cells of P. globosa to cell-free culture filtrates of Skeletonema costatum and analyzed the response using tandem mass tag (TMT)-based quantitative proteomics combined with physiological analysis. Both 15% and 25% culture filtrate treatments significantly increased colony density and colony diameter. Among the 3504 proteins identified, 282 and 403 were differentially expressed in the two treatments, respectively. Functional analysis of these differentially expressed proteins indicated activation of photosynthesis, carbohydrate metabolism, oxidative phosphorylation, DNA replication and repair, ribosome-related processes, ABC transporters, and pathways putatively associated with glycosaminoglycan biosynthesis. These changes indicate that filtrate exposure was accompanied by coordinated increases in energy production, carbon fixation, and metabolic processes related to extracellular-matrix precursor supply and transport, creating a physiological state favorable for colony development. Together, the physiological and proteomic data provide protein-level evidence that S. costatum culture filtrate promotes P. globosa colony formation and offer mechanistic insight into phytoplankton interactions during bloom succession.

Ethephon elicitation enhances biomass accumulation and phycobiliprotein production in Arthrospira platensis

Findings suggest that low-dose ethephon elicitation may be a simple strategy to enhance phycobiliprotein accumulation in Arthrospira platensis.

Enhancing carotenoid production in Chlorella sorokiniana through the protein-protein interaction between ORANGE and PSY.

The green microalga Chlorella sorokiniana FZU60, capable of achieving ultra-high biomass concentrations under heterotrophic conditions, is a promising chassis for carotenoid production. Enhancing intracellular carotenoid accumulation is an effective strategy to further improve the potential of this alga. ORANGE protein is recognized as a key post-transcriptional regulator of phytoene synthase (PSY), the rate-limiting enzyme in carotenoid biosynthesis, in higher plants. However, its function in microalgae remains unclear. In this study, the genomic structures of ORANGE and PSY in C. sorokiniana FZU60 (CsORANGE and CsPSY) were characterized, revealing GC-AG splice sites within their introns. Computational analysis predicted a stable interaction between CsORANGE and CsPSY, which was subsequently confirmed by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Heterologous co-expression of CsORANGE and CsPSY in carotenoid-engineered Escherichia coli significantly increased lycopene accumulation compared with expression of CsPSY alone. Moreover, CRISPR activation (CRISPRa)-mediated upregulation of endogenous CsORANGE significantly enhanced carotenoid accumulation in the engineered transformants. These results demonstrate that CsORANGE positively regulates carotenoid biosynthesis via direct protein-protein interaction with CsPSY in C. sorokiniana FZU60.

Vesicle-associated exudates from Alteromonas enhance growth and survival of Prochlorococcus in batch culture

ABSTRACT The cyanobacterium Prochlorococcus MIT9312 requires helping functions from co-existing organisms for survival under stressful conditions. Here, we show that the helper strain Alteromonas macleodii EZ55 also facilitates greater exploitation of medium resources by Prochlorococcus. The presence of Alteromonas allowed Prochlorococcus to grow to greater cell densities, delay growth cessation, and avoid cell death relative to axenic cultures, phenotypes potentially associated with Alteromonas-driven degradation of autotoxic substances made by Prochlorococcus. We found that heat-labile high-molecular-weight Alteromonas exudates mediated the beneficial impacts on Prochlorococcus, although it is unclear which specific exudate-associated activities were responsible. Both the composition and activity of the secreted material changed after 500 generations of experimental evolution, suggesting genetic control. Some exudates were located within extracellular vesicles, which were capable of physically associating with Prochlorococcus cells and were responsible for at least some of the growth enhancement effects. Many of the functionalities observed in Alteromonas exudates (e.g., increasing phosphate availability, hydrogen peroxide degradation, and siderophore capabilities) are consistent with leaky Black Queen processes (i.e., services provided by one organism that benefit the entire community) and favor the evolution of interdependencies in microbial communities. We discuss the potential ramifications of such processes being packaged into vesicles as opposed to freely diffusing through the extracellular milieu. IMPORTANCE Heterotrophic bacteria can facilitate improved growth for numerous phytoplankton, including the highly abundant cyanobacterium Prochlorococcus. Here, we show that for the “helper” interaction between Alteromonas and Prochlorococcus, this facilitation is relevant across all phases of batch culture growth and is mediated by secreted products, including proteins and membrane vesicles. We explore the composition of these exudates and show evidence that they are altered during evolutionary adaptation in a changed environment. Heterotrophic bacteria can facilitate improved growth for numerous phytoplankton, including the highly abundant cyanobacterium Prochlorococcus. Here, we show that for the “helper” interaction between Alteromonas and Prochlorococcus, this facilitation is relevant across all phases of batch culture growth and is mediated by secreted products, including proteins and membrane vesicles. We explore the composition of these exudates and show evidence that they are altered during evolutionary adaptation in a changed environment.