Torulene is a promising pink pigment, produced only by yeasts and fungi, and its production is still in a developing stage due to the low production rate. Accordingly, this study focuses on maximizing torulene production by Rhodotorula glutinis using shaken flask fermentation. The effect of different nitrogen sources, and C/N and C/S ratios on lipid and carotenoid production by R. glutinis was studied using 60 g/L glucose. The largest cells filled with golden fluorescence lipid bodies were observed using fluorescence microscopy when peptone was used as a nitrogen source. The highest total pigment (0.947 mg/L) and carotenoid relative productivity (Car-RP) (89.04 µg/g) were obtained at C/N 146 and C/S 120, and with ammonium sulfate as a nitrogen source, with 62% torulene domination using High Performance Liquid Chromatography (HPLC) for identification. Under a high C/N ratio, regardless of the C/S ratio, the carotenoid synthesis rate decreased after three days while the lipid synthesis rate kept increasing to the sixth day. Interestingly, after adding 0.7 mM Al₂(SO₄)₃ to the optimized medium, the total pigment and Car-RP (2.2 mg/L and 212.9 µg/g) sharply increased, producing around 2.16 mg/L torulene (98%) with around 50% decrease in lipid yield. This is the first report on the role of Al₂(SO₄)₃ for enhancing torulene production under lipogenesis condition, which could be used as a potential tool for torulene production.

Introduction: Hyperlipidemia, a prevalent metabolic disorder with rising global incidence, has become a major public health concern. Probiotics allow for a mild intervention strategy for hyperlipidemia management that has garnered increasing attention.Methods: In this study, we investigated the therapeutic effects and underlying mechanisms of Lactobacillus paragasseri HM018 in hypercholesterolemic rats.Results and discussion: We established three dosage groups (2.5 × 10⁸, 5 × 10⁸, and 1.5 × 10⁹ CFU/rat), demonstrating that HM018 significantly reduced high-fat diet-induced serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels, while ameliorating gut microbiota dysbiosis and decreasing the Firmicutes/Bacteroidetes ratio. Our transcriptomic analysis revealed that HM018 markedly upregulated Apoa1 expression both in the ileum and liver, while enhancing Abcg5/Abcg8 gene expression to promote β-sitosterol efflux. Concurrently, hepatic Cocs2/3 and Cish gene expression was downregulated, attenuating their inhibitory effects on hormonal and glucagon signaling, thereby improving glucose and lipid metabolism. Metabolomic profiling further indicated that HM018 significantly altered bile acid composition by modulating gut microbiota-mediated bile acid metabolism. In conclusion, Lactobacillus paracasei HM018 could ameliorate hyperlipidemia through multiple pathways, including gut microbiota modulation, hepatic lipid/glucose/bile acid metabolism improvement, and intestinal cholesterol efflux gene expression enhancement.

Introduction: The fermentation of lactic acid bacteria can alter the nutraceutical and functional efficacy of food and medicinal products, particularly when involving bioactive compounds similar to those in Poria cocos (P. cocos), which include polysaccharides and triterpenoids. In this study, we used Limosilactobacillus reuteri HM-R28 (L. reuteri HM-R28) from breast milk to ferment P. cocos in a liquid state and investigated changes in the physicochemical properties and metabolic composition before and after fermentation.Methods: Additionally, we evaluated the effect of L. reuteri HM-R28 on the antioxidant activity and polysaccharide content of the P. cocos fermentation broth to elucidate its role.Results and discussion: Fermentation with L. reuteri HM-R28 enhanced the antioxidant activity of the fermentation solution. Liquid fermentation significantly altered the metabolites of P. cocos. Based on the broadly targeted metabolomics analysis, a total of 549 differential metabolites were detected in the fermentation broth before and after fermentation, with 254 metabolites significantly upregulated and 295 metabolites significantly downregulated. These differential metabolites were associated with 41 metabolic pathways, primarily involving lipids and lipid constituents, organic acids and their derivatives, and heterocyclic organic compounds. Liquid fermentation also increased antioxidant compounds such as sedanolide, pomegranate acid, and epigallocatechin, along with aromatic volatile substances such as delta-tridecanolactone, γ-nonanolactone, and 3-acetyl-2, 5-dimethylfuran. These insights establish a conceptual framework for advancing the use of human milk-derived lactic acid bacteria for fermenting medicinal and edible homologous products. To our knowledge, this is the first study to elucidate the role of human milk-derived probiotics in enhancing the bioactive compounds of P. cocos through fermentation. Our findings can provide a theoretical foundation for the development of medicinal and edible homologous products fermented with human milk-derived Lactobacillus strains.

Sugar esters are a relevant class of important bio-surfactants. In comparison to the chemical procedure, enzymatic transesterification by microbial lipases prefers gentle reaction conditions and minimal energy costs. In this work, a novel sugar ester was synthesized by the modified cold-adapted lipase (lip-∆lid, lip-F144A, lip-F144V). In addition, combined with the immobilization of organic-inorganic hybrid nanoflowers, the effects of three metal ions on the activity of immobilized lipase were investigated, LHNs(Ca) has the highest activity, k_cat/K_m of LHNs(Ca)-lip-∆lid is twice that of the free enzyme. Furthermore, comparing the conversion rate of fructose laurate ester synthetized, LHNs(Ca)-lip-∆lid (58.36%) is significantly higher than that of LHNs(Ca) (41.73%) for 48 h at 40 °C, even much higher than commercial lipase CALB and RML, which indicated that the substrate affinity and catalytic efficiency of Lip ZC12 modified by lid truncation were significantly improved. Fructose lauric acid monoester and diester behave like ordinary surfactants, that can act as a detergent, with potential applications in a variety of cleaning processes. The emulsification of monoester is higher than SDS in soybean oil phase, and both higher than diester, Therefore, these findings indicated that the LHNs(Ca) nanoparticles are suitable carriers for immobilizing modified cold-adapted lipase, and the immobilized lipase can be used as an innovative green approach to the synthesis of sugar esters in food industry.