Phosphorus Transformation Routines And Genomic Analysis Of The Highly Efficient Phosphorus Accumulating Bacteria Acinetobacter

With the development of molecular biology,new types of phosphorus accumulating bacteria and special phosphorus removal mechanisms have been gradually discovered by researchers.The biological phosphorus removal mechanism of denitrifying phosphorus accumulating bacteria and Tetrasphaera bacteria is obviously different from the traditional phosphorus accumulating Mino model,and their functions in the sewage treatment system are gradually enlarged.This indicates that the diversity and metabolic mechanism of phosphorus accumulating bacteria are far more abundant than known.In this paper,by analyzing the metabolic mechanism and phosphorus conversion pathway of a novel Acinetobacter during the growth process,and combining with the functional gene annotation of the genome,the metabolic model of the phosphorus accumulating bacteria was reconstructed.The main results are as follows:1.Three high-efficiency phospho-accumulating strains with aerobic phosphorus uptake rate of more than 75% were isolated from the laboratory and identified as highly homologous to Acinetobacter,Klebsiella and Enterobacter,respectively.The NCBI registration numbers of 16 S r DNA sequences are OL519151,OL519152 and OL519153 respectively.The effects of p H value,temperature and carbon source on the three strains were investigated,and the maximum phosphorus removal efficiency reached 89.4%,85.43% and 76.95%,respectively.2.Acinetobacter sp.PK01 strain can use glucose and sodium acetate as carbon sources for growth and metabolism under aerobic conditions,and a large amount of extracellular phosphate is absorbed to synthesize poly-P,and the concentration of intracellular glycogen remains constant under all conditions.At the aerobic growth stage,experiments with different initial phosphorus concentrations showed that the strain absorbed BS-IP into cells for growth metabolism and synthesis of Poly-P,and EPS adsorption also played a certain role in phosphorus removal.After depletion of BS-IP,IP absorbed by EPS was preferentially used for cell growth and metabolism,but not for poly-P synthesis.When BS-IP and EPS-IP were depleted,poly-P could be used to decompose and transform phosphorus form and supplement IP components needed for cell metabolism.3.Under anaerobic conditions,the strain can only use glucose as an external carbon source for growth and metabolism,producing VFAs and expelling it to the outside of the cell.PHB is not produced in the bacterial cell but other lipids may exist.Poly-P is significantly decomposed while Pi does not.released into the environment.The results of phosphorus conversion distribution showed that a part of IN-IP was converted into IN-OP and SMP-OP,which indicated that the bacteria still carried out cell growth and reproduction metabolism in the anaerobic stage,and a part of IN-IP was converted into EPS-IP and EPS-OP,There was a certain correlation between the growth of EPS-OP and the change of EPS concentration,which indicated that the EPS produced by bacterial metabolism in the anaerobic stage might be dominated by organophosphorus compounds,such as phospholipids and nucleic acids.The growth of EPS-IP indicated that the anaerobic EPS still had the adsorption effect on IP,and the IP was directly derived from IN-IP.4.Reconstruct metabolic pathways based on genome functional annotations,including glycolysis,gluconeogenesis,TCA cycle,half-TCA cycle,and polyphosphate metabolism.The complete genome sequence of this strain has been deposited in the NCBI database(SUB11203395).During anaerobic and phosphorus-deficient culture,glucose enters cells through two pathways,MFS and PTS.There is no PHA synthesis gene in the genome,and acetyl-Co A generates long-chain fatty acids through the fatty acid biosynthesis pathway,which is finally synthesized into phospholipids and wax esters.The Actp system is strictly dependent on H+ and Na+ for the transport of acetic acid to the outside of the cell,and the Pit transporter can rely on the reduction of cations to cause more Pi to exist in the form of complexes,so the anaerobic phosphorus release is not obvious.During aerobic and phosphorus-rich culture,extracellular VFA and intracellular wax esters can be converted into acetyl-Co A for TCA cycle and gluconeogenesis,Pit and Pst systems simultaneously absorb extracellular IP to synthesize Poly-P.