Molecular indicators of Nitrobacter spp. population and growth activity during an induced inhibition event in a bench scale nitrification reactor

摘要: Abstract The Nitrobacter spp. ribosomal RNA gene (rDNA) and transcript (rRNAt) abundance were quantified in a bench scale nitrification reactor during baseline periods of high efficiency an intervening staged inhibition event. to ratio (rRNAt/rDNA) was highly sensitive changes the nitrite oxidation rate. During efficiency, rRNAt/rDNA metric displayed range from 0.68 2.01 with one-sided ( α  = 0.10) lower upper prediction intervals 0.70 1.78, respectively. When inhibited by disabling pH control system, this activity metric declined order magnitude ∼0.05, well below interval reflecting efficiency. decline rapid (2 h) preceded significant drop performance, which occurred as ammonia accumulated. remained low (∼0.05) for several days after system re-enabled at setpoint 8.0, otherwise induced accumulated produced free concentrations. timing subsequent increase ratio, which transiently exceeded established period not coincidental resumption 7.2 that lowered concentrations non-inhibitory levels. Rather, resumed increased only complete, reduced oxygen demand. In summary,  rRNAt/rDNA activity reflected timely easily recognizable activity, illustrating that molecular data can be used diagnose poor biological wastewater treatment performance.