The untapped genetic diversity of extremophilic microalgae provides distinctive physiological and biochemical traits with potential to support Sustainable Development Goal (SDG) 6 (Clean Water and Sanitation), SDG 7 (Affordable and Clean Energy), and SDG 15 (Life on Land). This review examines the diversity, stress-adaptation mechanisms, and biotechnological potential of extremophilic microalgae, with emphasis on their roles in resource recovery, carbon utilization, and bioproduct generation. Their ability to maintain cellular functions under extreme salinity, pH, temperature, radiation, and nutrient conditions enables their cultivation in environments that may be unsuitable for conventional production systems and facilitates the accumulation of lipids, pigments, carbohydrates, proteins, and other bioactive metabolites. These characteristics create opportunities to couple wastewater treatment, carbon capture and utilization, and biomass valorization within circular bioprocesses. However, laboratory-scale demonstrations should not be equated with established environmental or commercial benefits, as strain-specific physiological requirements, energy demand, process control, harvesting, downstream processing, and resource inputs can constrain scale-up. The review therefore emphasizes the need to evaluate extremophilic microalgal systems using integrated techno-economic and life-cycle approaches rather than biological productivity alone. Future advances will depend on combining multi-omics, metabolic engineering, adaptive cultivation, process optimization, and predictive modeling to identify robust strains and cultivation strategies. Such integration could accelerate the translation of extremophile-based bioprocesses into resource-efficient and economically credible applications for environmental sustainability.

A static magnetic field (SMF)-assisted liquid-state fermentation strategy using Lacticaseibacillus paracasei (L. paracasei) is proposed to improve the comprehensive utilization value of Ginkgo biloba leaves. Taking total flavonoid extraction yield as the objective, Box-Behnken response surface methodology was adopted to optimize the fermentation process. Meanwhile, the nutritional components and hypoglycemic activity of Ginkgo biloba leaves in vitro before and after fermentation were compared and analyzed. The optimal fermentation conditions were determined as follows: 3-fold-diluted De Man, Rogosa, and Sharpe (MRS) medium, an SMF intensity of 4.2 mT, an SMF duration of 2.9 h, and an inoculum size of 6.5%. Under these conditions, the total flavonoid extraction yield reached (3.41 ± 0.11)%, which was 3.33 times that of unfermented raw material. Analysis of the nutritional components revealed that after SMF-assisted fermentation, crude protein and crude fat contents increased by 59.58% and 13.72%, while ash and crude fiber contents decreased by 24.84% and 35.66%, respectively. SMF application also significantly affected the crude fiber content (p < 0.05). Meanwhile, the contents of phytic acid, tannins, phenolic acids, and ginkgolic acids in the SMF-assisted group declined by 29.56%, 43.10%, 23.42%, and 50.37%, respectively, and the SMF further promoted the degradation of anti-nutritional factors. Hypoglycemic activity analysis indicated that fermentation markedly enhanced the inhibitory effect of Ginkgo biloba leaf-derived flavonoids against α-glucosidase and α-amylase, and that SMF stimulation may also contribute to strengthening this inhibitory activity. This study demonstrates that SMF-coupled probiotic fermentation is an effective and environmentally friendly approach for processing Ginkgo biloba leaves, providing experimental support for high-value utilization of plant-based resources through physical-field-assisted microbial fermentation.