Separation and identification of fatty acid esters of algal carotenoid metabolites in the freshwater mussel Dreissena bugensis , by liquid chromatography with ultraviolet/visible wavelength and mass spectrometric detectors in series

Biodegradation of triphenylmethane dye crystal violet by Cedecea davisae

The present study focuses on the biodegradation of triphenylmethane dye crystal violet (CV) by Cedecea davisae. The degradation of CV was evaluated via ultraviolet absorbance at 254 nm (UV₂₅₄) and chemical oxygen demand (COD) removal, and the kinetics was used to evaluate the degradation efficiency. Intermediate products were analyzed via UV-vis spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), and high-performance liquid chromatography (HPLC). Results showed that C. davisae was able to decolorize the CV, and the maximum decolorization ratio reached 97%. COD reduction was observed after decolorization, with average removal rates of >90% after 48 h. Moreover, 50% of UV₂₅₄ can be removed after 14 h. The removal efficiency of CV by C. davisae followed first- and second-order reaction kinetics at temperature ranged from 20 °C to 40 °C and pH 4.0 to 6.0, respectively. By using UV, the peak representing the CV disappeared 14 h after CV decolorization, and the degradation of aromatic and naphthalene rings was attributed to the formation of a new metabolite. The FTIR spectra of metabolites showed that a new functional group of OH, CH, CH₂, CH₃, NH, CN, CN, or CO was produced. The chromatograms of HPLC recorded at 589 nm at retention time decreased and were not detected following incubation for 8 h by C. davisae.

A novel strategy for isolation and purification of fucoxanthinol and fucoxanthin from the diatom Nitzschia laevis

In this study, the microalga Nitzschia laevis (N. laevis) can accumulate a marine carotenoid fucoxanthinol. In particular, fucoxanthinol was firstly isolated from microalgae, accompanied by its derivative fucoxanthin. The identification and quantification of fucoxanthinol and fucoxanthin were determined by ultra-performance liquid chromatography coupled to photodiode array detector-quadrupole/travelling-wave ion mobility mass spectrometry/time-of-flight mass spectrometry (UPLC-PDA-TWIMS-QTOF-MS). Furthermore, a cost-effective approach mediated with solid-phase extraction (SPE) and thin-layer chromatography (TLC) technique was used to isolate and purify fucoxanthinol and fucoxanthin from the extracts of N. laevis. This two-step method can obtain 98% fucoxanthinol and 95% fucoxanthin, with the recovery efficiencies of around 85% for fucoxanthinol and 70% for fucoxanthin, respectively. Moreover, ¹H and ¹³C nuclear magnetic resonance (NMR) techniques were adopted to record the purified compounds for supporting the above results. In all, the developed method has a promising potential to purify fucoxanthinol and fucoxanthin of microalgae for food and pharmaceutical applications.