The impact of tetracycline on simultaneous biological wastewater nitrogen and phosphorus removal and its fundamental mechanisms were investigated in this study. Compared with the control, a lower concentration of tetracycline (0.2 mg L À1 ) did not exert adverse effects on biological nutrient removal; however, the presence of 2 and 5 mg L À1 of tetracycline decreased the total nitrogen removal efficiency from 80.2% to 69.2% and 65.1% respectively, but they showed marginal influence on phosphorus removal. The mechanism studies showed that most of the influent tetracycline was adsorbed by sludge, which induced the release of extracellular polymeric substances (EPS) from a sludge matrix, decreased the protective role of EPS on bacterial cells, declined the viability of sludge, increased the sludge volume index, and caused the detachment of denitrifying bacteria from sludge. Thus, the denitrifiers were more easily contacted with tetracycline. Further investigation revealed that it was the denitrifiers instead of nitrifiers being negatively affected by tetracycline, and the generation of electron donor for denitrification via intracellular polyhydroxyalkanoates (PHA) decomposition was depressed. In addition, tetracycline inhibited the activities of nitrate reductase and nitrite reductase as it was a strong chelating agent which reduced the free copper ions.

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Purpose A large-scale managed reed wetland in Yancheng Biosphere Reserve of China has been irrigated by treated papermaking wastewater (TPW) for approximately 8 to 12 years. This report details the risk evaluation of long-term TPW irrigation on the soil and its microbial viability, providing important perspective on the suitability of TPW reuse for irrigation. Materials and methods An extensive field survey was employed for assessing the impacts of long-term TPW irrigation of reed fields (F1 to F6), as compared to river water irrigated field, on soil physicochemical properties, accumulation of heavy metals (Cu, Cd, Pb), soil enzyme activities (i.e., urease, invertase, catalase, and polyphenol oxidase), and soil microbial community metabolic profiles. Results and discussion The results revealed that long-term

To explore the response of the soil microbial community to nitrobenzene (NB) exposure in a Spartina marsh, a short-term (45 d) mesocosm study was conducted at three NB concentrations of (10, 50, and 100) mg kg −1 . Dry soil, sterile and unsterile controls were also compared. The ability of the microbes to biodegrade NB was studied in an effort to predict the outcome of NB in the mesocosm. The results indicated that a microbial community is capable of doing so. Microbial enumeration and enzyme assays showed that the fluctuations in microbial communities and polyphenol oxidase activities are related to the initial NB concentration. Moreover, cluster analyses through denaturing gradient gel electrophoresis (DGGE) revealed very similar patterns (95.5%) throughout the 45 d term, indicating that the microbial community regenerates when NB is exhausted. Although volatilization and photolysis were the major processes responsible for the reduction in NB in contaminated mesocosms and the microbial community regenerated at the end of incubation, the data indicate potential ecological risks in outfall areas even if the discharged wastewater complies with the national wastewater discharge standards.

Chaetominine (CHA), an alkaloid with biological activity produced by Aspergillus fumigatus CY018, has strong anticancer activity against the human leukemia cell. However, its further research for pharmacokinetics is limited by CHA production in submerged fermentation, which is a problem urgently awaiting solutions by effective biological strategies. In this work, Ca 2+ and Al 3+ exhibited a strong promoting effect on CHA production after multiple metal ions screening. Then, the concentration of Ca 2+ and Al 3+ and the addition time was optimized. The suitable conditions were 0.5 mM Ca 2+ and 0.5 mM Al 3+ at 120 h, in which the CHA production reached 58.5 and 49.45 mg/L with optimized condition of Ca 2+ and Al 3+ respectively. The intermediate metabolites, such as DAHP, chorismate and tryptophan, were increased obviously with addition of Ca 2+ and Al 3+ . The activities of key enzymes of DAHPs, AroAs and TrpCs in CHA biosynthesis pathway were improved by 3.58-, 3.60-and 3.34-folds respectively. Meanwhile, the transcription levels of laeA, dahp, cs, and trpC were upregulated by 3.22-, 12.65-, 5.58-and 6.99-fold respectively by addition of Ca 2+ and Al 3+ . Additionally, the fermentation strategy was successfully scaled up to 5 L reactor, in which CHA production could attain 75.6 mg/L at 336 h. This work demonstrated that Ca 2+ and Al 3+ co-addition was an effective strategy for increasing CHA production, and the information obtained might be useful to the further improvement of CHA fermentation on large scale.