The biological nitrogen removal technology utilizing heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has shown effectiveness in wastewater treatment. However, the nitrogen removal efficiency of HN-AD bacteria significantly decreases as the salinity increases. To tackle the challenge of treating high-salt and high-nitrogen wastewater, we isolated a moderately halophilic HN-AD strain 5505 from a salt lake in Xinjiang. The strain was identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence. Single-factor experiments were carried out with NH₄⁺-N, NO₃^--N, and NO₂^--N as sole or mixed nitrogen sources to study the nitrifying effect, denitrifying effect, and nitrogen metabolism pathway of the strain. The strain was identified as Halomonas sp.. It can grow in the presence of 1%-25% (W/V) NaCl and exhibited efficient nitrogen removal ability in the presence of 3%-8% NaCl. At the optimal NaCl concentration (8%), the strain showed the NH₄⁺-N, NO₃^--N and NO₂^--N removal rates of 100.0%, 94.11% and 74.43%, respectively. Strain 5505 removed inorganic nitrogen mainly by assimilation, which accounted for over 62.68% of total nitrogen removal. In the presence of mixed nitrogen sources, strain 5505 showed a preference for utilizing ammonia, with a potential HN-AD pathway of NH₄⁺→NH₂OH→NO₂^-→NO₃^-→NO₂^-→NO/N₂O/N₂. The findings provide efficient salt-tolerant bacterial resources, enhance our understanding of biological nitrogen removal, and contribute to the nitrogen removal efficiency improvement in the treatment of high-salt and high-nitrogen wastewater.
Halomonas/classification* ; Nitrogen/isolation & purification* ; Denitrification ; Nitrification ; Wastewater/microbiology* ; Aerobiosis ; Biodegradation, Environmental ; Salinity

OBJECTIVE To investigate the role of several xenobiotic metabolism-associated CYP450 isoforms in the auto-activation of hepatic stellate cells(HSCs) invitro. METHODS HSCs were isolated from adult Wistar rats and cultured on plastic as an in vitroauto-activation model. Positive expression of α-smooth muscle actin(α-SMA)was used as an activated marker of HSCs and detected by immunocytochemical staining in HSCs cultured for 1,2,5 or 11 d. The expressions of CYP450 isoforms were analyzed by real-time RT-PCR in the HSCs. RESULTS The immunocytochemical stai-ning showed no α-SMA expression in HSCs cultured for 1 d,while its expression gradually increased during culture since day 2. ln terms of α-SMA expression,HSCs cultured for 1,2,5,and 11 d were classified as the quiescent,early,middle and later stages of activation,respectively. The RT-PCR results revealed that CYP1B1,CYP2B1/ 2,and CYP2E1 mRNA were expressed at high levels in the early stage of HSCs activation(at day 2),which were 2.1-,1.6-,and 23.9-fold those in the quiescent HSCs(day 1),respectively. Further study revealed that mRNA expressions of these up-regulated CYPs in the early stage of activation were diminished at the subsequent two stages. The levels of CYP1A1 and CYP1A2 mRNA decreased constantly throughtout the activation process. CONCLUSION Multiple xenobi-otic metabolism-associated CYP450 isoforms might be involved in the auto-activation of rat HSCs invitro.

AIM: To activate hepatic stellate cells (HSC) in vitro in precision-cut liver slices (PCLS) stimulated by acetaldehyde for studying and screening anti-fibrotic drugs. METHODS: PCLS were prepared by the vibratome, and incubated with 700 ?m?L~-1 acetaldehyde for 0, 2, 4 and 6 h. The medium and homogenate were retained to determine glutathione S-transferase (GST) activity, lactate dehydrogenase (LDH) leakage and hydroxyproline (Hyp) content. PCLS were prepared for paraffin sections. The expression of ?-smooth muscle actin (?-SMA) was evaluated by immunohistochemistry, and the result was analyzed with image analysis software. RESULTS: The leakages of GST and LDH were increased significantly compared with those in 0 h group (P