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 assess and compare chemical and immunochemical fecal occult blood tests (FOBTs) in diagnosis of gastrointestinal hemorrhage and their clinical significance. Methods The FOBT was carried out in 4474 in-patients, out-patients or subjects who had annual physical examination using both hemoccult Ⅱ (CFOBT) and colloidal gold chromagraphy (IFOBT) methods.Those who was positive for FOBTs would be re-tested for 2 times and followed by gastroscopy and colonoscopy as well as other examinations in order to find the reason and location of gastrointestinal hemorrhage. Results FOBT was positive in 390 (8.22%) patients, of which 163 (41.8%) were detected by CFOBT, 100(25.6%) by IFOBT, and 127(32.6%) by both CFOBT and IFOBT. The clinical, endoscopic and other examinations revealed that upper and lower gastrointestinal bleeding were found in 235 (60.3%) and 136 (34.9%) patients, respectively. The detective rates of upper and lower gastrointestinal bleeding were 90.2% and 67.6% by CFOBT respectively, and 42.5% and 93.4% by IFOBT, respectively. The obvious gastrointestinal bleeding could be detected by both CFOBT and IFOBT. The diseases related to gastrointestinal bleeding involved acute gastric mucosal lesion, peptic ulcer, gastric cancer and colonic polyp,colorectal cancer and piles, etc. Conclusions It is demonstrated that FOBT is still important in screening and diagnosis of gastrointestinal hemorrhage.The CFOBT is superior to IFOBT in detecting upper gastrointestinal bleeding, whereas the IFOBT is superior to CFOBT in detecting lower gastrointestinal bleeding.