Pyropia yezoensis (red algae) or commonly known as nori, is highly regarded for its nutritional benefits and distinct taste, leading to its widespread consumption. The bio-activity and sensory characteristics of P. yezoensis are attributed to the metabolites it contains. In this study, identification and quantification of the diverse range of metabolites of P. yezoensis and metabolomic analysis were conducted using gas chromatography-mass spectrometry (GC-MS). Furthermore, the impact of high temperature on its metabolites regulation was also investigated. Due to metabolomic analysis, a diverse range of metabolites were identified in P. yezoensis , including lipids, amino acids, carbohydrates, and secondary metabolites. Several known bioactive compounds, including alcohol and polyols, amines, amino acids-peptides-analogues, beta hydroxy acids and derivatives, carbohydrates and carbohydrate conjugates, cholestane steroids, dicarboxylic acid and derivatives, and fatty acids and conjugates were detected in abundance, highlighting the nutritional and functional properties of P. yezoensis . Additionally, the metabolites composition of P. yezoensis was significantly affected in high temperatures, which led to up-regulation of considerable primary metabolites and few were down-regulated, and suggested a potential response and adaptation mechanism of P. yezoensis to elevated temperature conditions. This research highlighted the metabolomics of P. yezoensis , provided insights into its metabolite composition and regulatory responses to high temperature conditions, enhanced our knowledge of the biochemical pathways and adaptive mechanisms of P. yezoensis , which can assist the improvement strategies of utilization and cultivation to promote this valuable alga in response to fluctuating environmental conditions.
Despite the increased research efforts aimed at understanding iron-based conductive materials (CMs) for facilitating chain elongation (CE) to produce medium chain fatty acids (MCFAs), the impact of these materials on microbial community functions and the adaptation mechanisms to their biotoxicity remain unclear. This study found that the supply of zero-valent iron (ZVI) and magnetite enhanced the MCFAs carbon-flow distribution by 26 % and 52 %, respectively. Metagenomic analysis revealed the upregulation of fatty acid metabolism, pyruvate metabolism and ABC transporters with ZVI and magnetite. The predominant functional microorganisms were Massilibacterium and Tidjanibacter with ZVI, and were Petrimonas and Candidatus_Microthrix with magnetite. Furthermore, it was demonstrated that CE microorganisms respond and adapt to the biotoxicity of iron-based CMs by adjusting Two-component system and Quorum sensing for the first time. In summary, this study provided a new deep-insight on the feedback mechanisms of CE microorganisms on iron-based CMs.
The microbial reduction of nitrate in the presence of nanoscale zero-valent iron (nZVI) was evaluated to assess the feasibility of employing nZVI for biological denitrification treatment. The effect of modified nZVI on the growth, metabolism, and denitrification performance of Alcaligenes sp. TB under aerobic conditions was studied. Results showed that Alcaligenes sp. TB with nZVI/Pd had 31.5% increase in nitrate removal and 18.1% decrease in nitrite accumulation within 28 h. nZVI/Pd exhibited less inhibition on the cell growth (OD 600 = 0.725), NADH/NAD + ratio (86% of control), and electron transfer system activity (68.5% of control). In addition, nZVI/Pd decreased the membrane fluidity by increasing the trans/cis isomerization ratio (317.7% of control) to enhance the resistance of nZVI. This study underlines the effects of nZVI/Pd on membrane susceptibility via membrane fatty acid transformation during denitrification and suggests the influence of engineered nanomaterials on denitrification.
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