Raffinose, a trisaccharide abundantly found in soybeans, is a potential alternative carbon source for biorefineries. Nevertheless, residual intermediate di- or monosaccharides and low catabolic efficiency limit raffinose use through conventional microbial hosts. This study presents a Vibrio-based platform to convert raffinose efficiently. Vibrio sp. dhg was selected as the starting strain for the Adaptive Laboratory Evolution (ALE) strategy to leverage its significantly higher metabolic efficiency. We conducted ALE on a solid minimal medium supplemented with raffinose to prevent the enrichment of undesired phenotypes due to the shared effect of extracellular raffinose hydrolysis among multiple strains. As a result, we generated the VRA10 strain that efficiently utilizes raffinose without leaving behind degraded di- or monosaccharides, achieving a notable growth rate (0.40 h^-1) and raffinose consumption rate (1.2 g/g_dcw/h). Whole genome sequencing and reverse engineering identified that a missense mutation in the melB gene (encoding a melibiose/raffinose:sodium symporter) and the deletion of the two galR genes (encoding transcriptional repressors for galactose catabolism) facilitated rapid raffinose utilization. The further engineered strain produced 6.2 g/L of citramalate from 20 g/L of raffinose. This study will pave the way for the efficient utilization of diverse raffinose-rich byproducts and the expansion of alternative carbon streams in biorefinery applications.

2024-10-02·Nutritional Neuroscience

An extract of Hibiscus sabdariffa improves short-term memory in rats with experimental diabetic hyperglycemia

Article

作者: Ureña-Guerrero, Mónica E. ; Bañuelos-Pineda, Jacinto ; López-Pérez, Silvia J.

BACKGROUNDCalyxes of Hibiscus sabdariffa (Hs) contain anthocyanins, that normalize blood glucose levels (BGL) in diabetic patients. Diabetes also causes memory alterations, which could hypothetically decrease with the consumption of Hs.OBJECTIVESTo investigate the effect of dietary supplementation with a Hs extract on working memory and BGL in rats.METHODSDiabetic hyperglycemia (DHG) was induced with streptozotocin (STZ, 55 mg/kg i.p.) in Wistar rats. After 72 h DHG was confirmed, and the consumption of Hs extract began (50 mg/Kg/day). BGL and body weight (BW) were measured at 10, 20 and 30 days after DHG induction in controls and treated animals. Learning and short-term memory were evaluated after 30 days with Novel Object Recognition Test (NOR) and Barnes Maze (BM). The gross hippocampal structure was histologically analyzed.RESULTSSTZ-treated animals presented low BW and persistent DHG (BGL <300 mg/dL). Diabetic animals consuming the Hs extract had a dual response: some showed BGL comparable to controls, while others had levels comparable to diabetic animals not consuming extract. Diabetic animals that consumed the Hs extract had a better performance in NOR and BM than the diabetic animals not consuming the extract. At the histological level, hippocampal morphological differences were observed between diabetic animals that consumed the extract and those that did not.DISCUSSIONThe Hs extract used here could be a good co-adjuvant in the treatment of DHG, aimed at mitigating memory deficits and high BGL. These beneficial effects could be attributed to the anthocyanin content in the extract.

2024-09-01·Water Research

Mercury sources, transport, and transformation in rainfall-runoff processes: Mercury isotope approach

Article

作者: Peng, Tao ; Li, Ping ; Yan, Junyao ; Zhu, Wei ; Zhang, Lin ; Wang, Chuan ; Feng, Xinbin ; Li, Ruolan ; Yang, Shaochen ; Zhang, Leiming

Mercury (Hg) in runoff water poses significant ecological risks to aquatic ecosystems that can affect organisms. However, accurately identifying the sources and transformation processes of Hg in runoff water is challenging due to complex natural conditions. This study provides a comprehensive investigation of Hg dynamics in water from rainfall to runoff. The Hg isotope fractionation in water was characterized, which allows accurate quantification of Hg sources, transport, and transformations in rainfall-runoff processes. Δ²⁰⁰Hg and corrected Δ¹⁹⁹Hg values can serve as reliable tracers for identifying Hg sources in the runoff water and the variation of δ²⁰²Hg can be explained by Hg transformation processes. During runoff migration processes, Hg from rainfall is rapidly absorbed on the land surface, while terrestrial Hg entering the water by the dissolution process becomes the primary component of dissolved mercury (DHg). Besides the dissolution and adsorption, microbial Hg(II) reduction and demethylation of MeHg were dominant processes for DHg in the runoff water that flows through the rice paddies, while photochemical Hg(II) reduction was the dominant process for DHg in the runoff water with low water exchange rates. Particulate Hg (PHg) in runoff water is dominantly originated by the terrestrial material and derived from the dissolution and adsorption process. Tracking sources and transformations of Hg in runoff water during the rainfall-runoff process provides a basis for studying Hg pollution in larger water bodies under complex environmental factors.

100 项与 Depolymerised holothuria glycosaminoglycan 相关的药物交易

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