Mechanism of trehalose-enhanced metabolism of heterotrophic nitrification-aerobic denitrification community under high-salt stress / 生物工程学报

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are aerobic microorganisms that can remove nitrogen under high-salt conditions, but their performance in practical applications are not satisfactory. As a compatible solute, trehalose helps microorganisms to cope with high salt stress by participating in the regulation of cellular osmotic pressure, and plays an important role in promoting the nitrogen removal efficiency of microbial populations in the high-salt environment. We investigated the mechanism of exogenous-trehalose-enhanced metabolism of HN-AD community under high-salt stress by starting up a membrane aerobic biofilm reactor (MABR) to enrich HN-AD bacteria, and designed a C150 experimental group with 150 μmol/L trehalose addition and a C0 control group without trehalose. The reactor performance and the community structure showed that NH4+-N, total nitrogen (TN) and chemical oxygen demand (COD) removal efficiency were increased by 29.7%, 28.0% and 29.1%, respectively. The total relative abundance of salt-tolerant HN-AD bacteria (with Acinetobacter and Pseudofulvimonas as the dominant genus) in the C150 group reached 66.8%, an 18.2% increase compared with that of the C0 group. This demonstrated that trehalose addition promoted the enrichment of salt-tolerant HN-AD bacteria in the high-salt environment to enhance the nitrogen removal performance of the system. In-depth metabolomics analysis showed that the exogenous trehalose was utilized by microorganisms to improve proline synthesis to increase resistance to high-salt stress. By regulating the activity of cell proliferation signaling pathways (cGMP-PKG, PI3K-Akt), phospholipid metabolism pathway and aminoacyl-tRNA synthesis pathway, the abundances of phosphoethanolamine, which was one of the glycerophospholipid metabolites, and purine and pyrimidine were up-regulated to stimulate bacterial aggregation and cell proliferation to promote the growth of HN-AD bacteria in the high-salt environment. Meanwhile, the addition of trehalose accelerated the tricarboxylic acid (TCA) cycle, which might provide more electron donors and energy to the carbon and nitrogen metabolisms of HN-AD bacteria and promote the nitrogen removal performance of the system. These results may facilitate using HN-AD bacteria in the treatment of high-salt and high-nitrogen wastewater.

Prognostic significance of NADPH quinine oxidoreductase 1 overexpression in head and neck squamous cell carcinoma / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the significance of NADPH quinine oxidoreductase 1 (NQO1) protein overexpression on prognostic evaluation of head and neck squamous cell carcinoma (HNSCC).</p><p><b>METHODS</b>NQO1 protein was detected in 162 of HNSCC, 45 cases of adjacent nontumor tissues and 26 samples of normal head and neck epithelia using EnVision immunohistochemical. Correlation between NQO1 overexpression and patients prognosis was also analyzed.</p><p><b>RESULTS</b>The positive rate and strongly positive rate of NQO1 protein were 84.0% (136/162) and 69.8% (113/162) in HNSCC, respectively, and both of which were significantly higher than either those in adjacent nontumor tissues and normal head and neck epithelia (both P < 0.01). NQO1 expression was significantly correlated with the clinical stage, pT and chemoradiotherapy of HNSCC (P < 0.01). Kaplan-Meier survival analysis showed that overall survival and disease-free survival rates were significantly higher in HNSCC patients with high level NQO1 expression than that those with low level of NQO1 expression (Log-rank = 6.625 , P = 0.010;Log-rank = 6.234 , P = 0.013). Additional analysis by Cox proportional hazard regression model showed that high level of NQO1 expression was an independent hazard predictor for overall survival of patients with HNSCC (Wald = 6.626, P = 0.008).</p><p><b>CONCLUSIONS</b>NQO1 expression level is closely correlated with the progression and prognosis of patients with HNSCC. High level of NQO1 expression may be used as an important indicator for patients with poor prognostic HNSCC.</p>