| 1 | Quorum sensing systems regulate heterotrophic nitrification-aerobic denitrification by changing the activity of nitrogen-cycling enzymes显示文摘Heterotrophic nitrification-aerobic denitrification(HNAD)is essential in diverse nitrogen-transforming processes.How HNAD is modulated by quorum sensing(QS)systems is still ambiguous.The QS system in Pseudomonas aeruginosa manipulates colony behavior.Here,we described the influence of the Pseudomonas quinolone signal(PQS)and N-acyl-L-homoserine lactone(AHL)on HNAD.The HNAD of P.aeruginosa was inhibited by the oversecretion of PQS.AHL-or PQS-deficient P.aeruginosa mutants had a higher ability for nitrogen removal.QS inhibited heterotrophic nitrification mainly via controlling the activity of nitrite oxidoreductase(NXR)and the depressed aerobic denitrification by regulating the catalytic abilities of nitric oxide reductase(NOR),nitrite reductase(NIR),and nitrate reductase(NAR).The addition of citrate as the sole carbon source increased the nitrogen removal efficiency compared with other carbon sources.Nitrite,as the sole nitrogen source,could be used entirely with only the moderate concentration of PQS contained.AHL and PQS controlled both nitrification and denitrification,suggesting that QS plays an important role in nitrogen cycle under aerobic conditions. | Ziqian Zhu Yang Yang Anran Fang Yu Lou Guojun Xie Nanqi Ren Defeng Xing | 2020 | Environmental Science and Ecotechnology2020，，2： | 2 |
| 2 | Direct evidence of microbiological water quality changes on bacterial quantity and community caused by plumbing system显示文摘Drinking water quality deteriorates from treatment plant to customer taps, especially in the plumbing system. There is no direct evidence about what the differences are contributed by plumbing system. This study compared the water quality in the water main and at customer tap by preparing a sampling tap on the water main. The biomass was quantified by adenosine triphosphate(ATP) and the microbial community was profiled by 454 pyrosequencing.The results showed that in distribution pipes, biofilm contributed >94% of the total biomass,while loose deposits showed little contribution(< 2%) because of the low amount of loose deposits. The distribution of biological stable water had minor effects on the microbiocidal water quality regarding both quantity(ATP 1 ng/L vs. 1.7 ng/L) and community of the bacteria. Whereas the plumbing system has significant contribution to the increase of active biomass(1.7 ng/L vs. 2.9 ng/L) and the changes of bacterial community. The relative abundance of Sphingomonas spp. at tap(22%) was higher than that at water main(2%), while the relative abundance of Pseudomonas spp. in tap water(15%) was lower than that in the water from street water main(29%). Though only one location was prepared and studied, the present study showed that the protocol of making sampling tap on water main offered directly evidences about the impacts of plumbing system on tap water quality, which makes it possible to distinguish and study the processes in distribution system and plumbing system separately. | Jun Li Anran Ren Ed van der Mark Gang Liu | 2022 | Journal of Environmental Sciences2022，34，6： | 0 |
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