To investigate the characteristics and metabolic mechanism of short-cut denitrifying phosphorus-removing bacteria (SDPB) that are capable of enhanced biological phosphorus removal (EBPR) using nitrite as an electron acceptor

an aerobic/anoxic sequencing batch reactor was operated under three phases. An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological

physiological

biochemical properties and 16S rDNA gene sequence analysis. Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand (COD)

phosphate

nitrite

poly-β-hydroxybutyrate (PHB)

and glycogen. The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans. As a kind of non-fermentative bacteria

the energy of strain YC was mainly generated from phosphorus release (96.2%) under anaerobic conditions with 0.32 mg P per mg synthesized PHB. Under anoxic conditions

strain YC accumulated 0.45 mg P per mg degraded PHB

which produced most of energy for phosphate accumulation (91.3%) and a little for glycogen synthesis (8.7%). This metabolic mechanism of strain YC is different from that of tradition

al phosphorus-accumulating organisms (PAOs). It is also found that PHB

a kind of intracellular polymer

plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification. Therefore

monitoring ΔP/ΔPHB and? ΔNO

2

-

-N/ΔPHB is more necessary than monitoring ΔP/ΔCOD

?ΔNO

2

-

-N/ΔCOD

or ΔNO

2

-

-N.