Partial denitrification is an alternative process to provide stable nitrite for anammox. In this study, based on full-scale and lab-scale experiments, achieving and control of partial denitrification and the microbial mechanism were studied for 17 months in municipal wastewater treatment plant (MWWTP). Using glucose (GLC) as sole carbon source, partial denitrification was successfully achieved with nitrite accumulation percentage (NAP) higher than 90%; whereas, using sodium acetate (NaAc) as sole carbon source, nitrite accumulation was effectively controlled with economic and efficient carbon usage. Candidatus Competibacter and Thaurea were the dominant communities for partial denitrification. Denitrifying glycogen accumulating organisms (DGAOs), Thauera, denitrifying phosphorus accumulating organisms (DPAOs), GAOs, PAOs and denitrifiers coexisted in MWWTP, resulting in COD specific removal rate (CODSRR) of 883.10 ~ 1188.92mgN/gMLVSS/h during partial denitrification. Through adjustment of Anoxic-Oxic (A/O) operation to anoxic operation, the growth of GAOs and PAOs could be limited.

Doped graphite-like coating (GLC) has aroused great interest as one of the most promising protective materials in marine applications. However, there is a lack of systematic research on the tribocorrosion and antifouling performance of doped GLC coatings in harsh marine environments. Herein, a multifunctional (Cr, Cu)-GLC coating with combined antifouling and tribocorrosion properties was prepared via a magnetron sputtering method. The experimental results indicate that the resultant coatings changed from a dense structure to a loose columnar structure with the increment of Cr and Cu doping amount. At the same time, the hardness of the coating gradually decreases, but the contact angle between coating and seawater gradually increases. The algae adhesion test reveal that the algae density on the surface of the (Cr, Cu)-GLC coating decreases from about 565 to 70/mm2 as the amount of doping increased. However, on the contrary, the friction coefficient of the coating under OCP condition increases from 0.06 to about 0.35. Overall, the mild doped (Cr, Cu)-GLC coating exhibits the best comprehensive properties, combining antifouling and tribocorrosion properties. The corresponded mechanisms are discussed in terms of the coating microstructure, antifouling, and tribocorrosion behavior.

Kakkalide and irisolidone, the main isoflavones of Flos Puerariae, exhibit a wide spectrum of bioactivities. Intestinal bacteria biotransformation plays an important role in the metabolic pathways of flavones, and is directly related to the bioactivities of the prodrugs after oral administration. To the best of our knowledge, the metabolic pathways of kakkalide and irisolidone in vitro have not been comprehensively studied yet. This paper describes the strategy using ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF MS) for the rapid analysis of the metabolic profiles of kakkalide and irisolidone after incubated with human and rat intestinal bacteria. Bacteria incubated samples were prepared and analyzed after incubated under anaerobic conditions for 48 h. A total of 17 metabolites, including parent compounds, were detected in human and rat intestinal bacteria incubated samples. The results obtained indicate that hydrolysis, dehydroxylation, demethoxylation, demethylation, hydroxylation, decarbonylation, and reduction were the detected metabolic pathways of kakkalide and irisolidone in vitro. The conversion rate of irisolidone in human and rat bacteria was 8.57% and 6.51%, respectively. Biochanin A was the relatively main metabolite of irisolidone, and the content of biochanin A in human and rat bacteria was 3.68% and 4.25%, respectively. The conversion rate of kakkalide in human and rat bacteria was 99.92% and 98.58%, respectively. Irisolidone was the main metabolite of kakkalide, and the content of irisolidone in human and rat bacteria was 89.58% and 89.38%, respectively. This work not only provides the evidence of kakkalide and irisolidone metabolites in vivo, but also demonstrates a simple, fast, sensitive, and inexpensive method for identification of metabolites of other compounds transformed by intestinal bacteria.

The thermostable 1,3-1,4-β-glucanase PtLic16A from the fungus Paecilomyces thermophila catalyzes stringent hydrolysis of barley β-glucan and lichenan with an outstanding efficiency and has great potential for broad industrial applications. Here, we report the crystal structures of PtLic16A and an inactive mutant E113A in ligand-free form and in complex with the ligands cellobiose, cellotetraose and glucotriose at 1.80Å to 2.25Å resolution. PtLic16A adopts a typical β-jellyroll fold with a curved surface and the concave face forms an extended ligand binding cleft. These structures suggest that PtLic16A might carry out the hydrolysis via retaining mechanism with E113 and E118 serving as the nucleophile and general acid/base, respectively. Interestingly, in the structure of E113A/1,3-1,4-β-glucotriose complex, the sugar bound to the -1 subsite adopts an intermediate-like (α-anomeric) configuration. By combining all crystal structures solved here, a comprehensive binding mode for a substrate is proposed. These findings not only help understand the 1,3-1,4-β-glucanase catalytic mechanism but also provide a basis for further enzymatic engineering.