Adaptive laboratory evolution (ALE) has been widely utilized as a tool for developing new biological and phenotypic functions to explore strain improvement for microalgal production. Specifically, ALE has been utilized to evolve strains to better adapt to defined conditions. It has become a new solution to improve the performance of strains in microalgae biotechnology. This review mainly summarizes the key results from recent microalgal ALE studies in industrial production. ALE designed for improving cell growth rate, product yield, environmental tolerance and wastewater treatment is discussed to exploit microalgae in various applications. Further development of ALE is proposed, to provide theoretical support for producing the high value-added products from microalgal production.

Astaxanthin, a high-value keto-carotenoid with potent antioxidant and health-promoting properties, has gained global attention as a sustainable nutraceutical and biotechnological product. The green microalgae Haematococcus pluvialis and Chromochloris zofingiensis represent two promising natural producers, yet they differ markedly in physiology, productivity, and industrial scalability. This review provides a focused comparative analysis of these two species, emphasizing their quantitative performance differences. H. pluvialis can accumulate astaxanthin up to ~3–5% of dry biomass but typically reaches biomass densities of only 5–10 g L⁻¹, whereas C. zofingiensis achieves ultrahigh biomass concentrations of 100–220 g L⁻¹ under heterotrophic fed-batch fermentation, although its astaxanthin content is much lower (~0.1–0.5% DW). While H. pluvialis remains the benchmark for natural astaxanthin due to its exceptionally high cellular content, its thick cell wall, slow growth, and strict phototrophic requirements impose major cost and operational barriers. In contrast, C. zofingiensis exhibits rapid and flexible growth under heterotrophic, mixotrophic, or phototrophic conditions and can achieve ultrahigh biomass in fermentation, though its ketocarotenoid flux and astaxanthin accumulation remain comparatively limited. Meanwhile, a rapidly growing patent landscape demonstrates global technological competition, with major portfolios emerging in China, the United States, and Europe, spanning chemical synthesis, microbial fermentation, algal metabolic engineering, and high-density cultivation methods. These patents reveal clear innovation trends—ranging from solvent-free green synthesis routes to engineered microalgae and yeast chassis for enhanced astaxanthin production—which increasingly shape industrial development strategies. By synthesizing recent advances in metabolic engineering, two-stage cultivation, and green extraction technologies, this review identifies key knowledge gaps and outlines a practical roadmap for developing next-generation astaxanthin biorefineries, with an emphasis on scalable production and future integration into broader biorefinery frameworks. The findings aim to guide future research and provide actionable insights for scaling sustainable, cost-effective production of natural astaxanthin.

Low molecular weight galactomannan (LMGM) alleviated diarrhea symptoms within two hours post-treatment, promoted intestinal water absorption, and regulated gut microbiota.

Saline cultivation can reduce freshwater demand and reshape the production physiology of high-value microalgae, yet the metabolic basis of strain-specific salinity tolerance remains unclear. Here, the astaxanthin-producing green microalga Chromochloris zofingiensis was examined by comparing the wild type (Cz-WT) with a cGMP-dependent protein kinase (PKG)-deficient mutant (Cz-pkg) under 100 mM NaCl. Physiological measurements were integrated with parallel ¹³C-glucose tracing, ¹³C metabolic flux analysis, LC–MS metabolomics, and time-series RNA sequencing. Relative to Cz-pkg, Cz-WT showed higher normalized fluxes from phosphoenolpyruvate to pyruvate and oxaloacetate, greater pyruvate-to-acetyl-CoA conversion, and enhanced tricarboxylic acid (TCA)-cycle activity, suggesting a greater potential to support energy and reducing-equivalent metabolism. Cz-pkg exhibited lower glucose-6-phosphate and 6-phosphogluconate levels, early NADH depletion, and reduced pools of several amino-acid- and nucleotide-related metabolites. At 24 h, 141 genes were co-upregulated and 228 co-downregulated in both strains, involving photosynthetic electron transport, antioxidant metabolism, glycolysis/gluconeogenesis, amino-acid metabolism, and terpenoid biosynthesis. Phosphatidylglycerophosphate synthase was upregulated in both strains, supporting membrane-lipid remodeling. Overall, the data provide flux-level evidence that the salt-sensitive mutant is constrained in glycolysis–TCA cycle coupling and energy–redox homeostasis during salinity acclimation. Direct PKG substrates and causal phosphorylation events were not examined in this study.