PfHMGB2 protects yellow catfish (Pelteobagrus fulvidraco) from bacterial infection by promoting phagocytosis and proliferation of PBL.

HMGB2, a member of the high mobility group box family, plays an important role in host immune responses. However, the mechanism of action of HMGB2 is not well understood. Herein, a homologue from yellow catfish (Pelteobagrus fulvidraco) was cloned and named PfHMGB2. The deduced amino acid sequence of PfHMGB2 possessed a typical tripartite structure (two DNA binding boxes and an acid tail) and shared 90% identity with the predicted HMGB2 from I. punctatus. The mRNA of PfHMGB2 was widely distributed in all 11 tested tissues in healthy fish bodies and was significantly induced in the liver and head kidney when yellow catfish were injected with inactivated Aeromonas hydrophila. Consistently, PfHMGB2 mRNA could also be induced in yellow catfish peripheral blood leucocytes (PBL) by lipopolysaccharide. The recombinant PfHMGB2 protein was purified from E. coli BL21 (DE3):pET-28a/PfHMGB2 and showed DNA-binding affinity. Moreover, rPfHMGB2 improved the phagocytosis and proliferation activity and upregulated the mRNA expression of the pro-inflammatory cytokine TNFα in yellow catfish PBL. These results indicated that PfHMGB2 could protect yellow catfish from pathogen infection by activating PBL.

Acute and persistent toxicity of Cd(II) to the microbial community of Anammox process.

In this study, the short- and long-term effects of Cd(II) on the bioactivity, nitrogen removal and microbial community of the anaerobic ammonia oxidation (Anammox) process were investigated by step-wise increasing Cd(II). The self-recovery ability of Anammox was also studied after long-term exposure in Cd(II). The bioactivity of anaerobic ammonia-oxidizing bacteria (AAOB) within short-term exposure of Cd(II) were detected by batch experiments. Results showed that Cd(II) had both acute and persistent toxicity to Anammox, the IC50 in short-term exposure was calculated as 5.43 mg L-1. Long-term exposure led to the microbial diversity increase, as well as the relative abundance decrease of AAOB in Anammox system. AAOB was continuously suppressed by Cd(II) in 1-20 mg L-1, while it had self-adaption to Cd(II) in 1-10 mg L-1. Anammox biofilm showed prominent adsorbing ability for cadmium, and the cadmium in biofilm was the key factor affecting Anammox.

Effect of Fe (II) in low-nitrogen sewage on the reactor performance and microbial community of an ANAMMOX biofilter.

In this study, the effect of Fe (II) on Anaerobic Ammonium Oxidation (ANAMMOX) process was investigated by step-wise increasing the Fe (II) in influent from 1 to 50 mg L-1. The nitrogen removal, biofilm property and the microbial community were analyzed in each phase. Results showed that, the anaerobic ammonia-oxidizing bacteria (AAOB) bioactivity and the nitrogen removal of ANAMMOX system were slightly improved to 0.58 from the initial 0.51 kg m-3 d-1 by Fe (II) in 1-5 mg L-1. The nitrogen removal was suppressed and could recover to the initial level during the same period under 10-20 mg L-1 Fe (II), while it did not recover to the initial level under 30 mg L-1 Fe (II) and showed no recovery performance under 50 mg L-1 Fe (II). The irreversible suppression threshold of Fe (II) was calculated as 50 mg L-1. The iron content in ANAMMOX biofilm presented linear correlation with the influent Fe (II) in 1-20 mg L-1, which then tended to be stable when Fe (II) was higher. Dehydrogenase activity (DHA) showed similar and faster response to Fe (II) than the microbial activity, and it was an effective pre-indicator for the nitrogen removal performance in the ANAMMOX system suffered Fe (II). The Fe (II) feeding firstly led to the relative abundance of AAOB decreased to 11.04% from the initial 35.46%, and finally picked up to 19.39% after the long-term acclimatization.

Influence of elevated Zn (II) on Anammox system: Microbial variation and zinc tolerance.

Nitrogen removal by anaerobic ammonium oxidation (Anammox) has attracted increasing attention in nowadays. An Anammox biofilter was subjected to a continuous loading of elevated Zn (II). The influence of Zn (II) on the nitrogen removal, microbial community and biofilm property was investigated in the condition of 23-26 °C and 3.5 h HRT. The nitrogen removal greatly decreased to 0.054 from the initial 0.502 kg m-3 d-1, with the Zn (II) addition. Anaerobic ammonia-oxidizing bacteria (AAOB) had self-adaption to Zn (II) in 1-10 mg L-1 and was significantly enhanced after long-term acclimatization, while the suppression threshold was 20 mg L-1. Soluble microbial products (SMP) increased correspondingly with Zn (II), while extracellular polymeric substance (EPS) climbed up initially and then decreased. Anammox biofilm performed the highest zinc adsorption as 158.27 mg g-1 SS in biofilm. High Zn (II) improved the microbial diversity and lowered the Candidatus Kuenenia abuandance to 1.38% from 20.89%.

Effect of CuO nanoparticles on ammonia removal and EPS secretion of CANON sludge in the presence of nitrite suppression.

Completely autotrophic nitrogen removal over nitrite (CANON) process was an innovative technology for nitrogen removal from wastewater. It is necessary to clear the impact of CuO nanoparticles (CuO NPs) on CANON process since the widespread utilize increased their opportunity for entering into wastewater. In this study, the short-term and long-term effects of CuO NPs on the ammonia removal and extracellular polymeric substance (EPS) secretion were analyzed in the presence of nitrite, with the CuO NPs of 0, 5, 10, 20, 50, 100, 200, and 500 mg L-1, respectively. Results suggested that low concentration of CuO NPs could enhance the ammonia removal. The inhibition threshold of CuO NPs on CANON sludge within short-term exposure was 20 mg L-1, while that of long-term exposure was 10 mg L-1. Both short-term and long-term exposure within CuO NPs significantly impacted the ammonia removal, and both the nitrite and CuO NPs influenced the EPS secretion.