Intact ladderane lipids are a special kind of phospholipids in the anammoxosome membrane of AnAOB.Phospholipid organic mixture was extracted respectively from four sludge samples in anaerobic EGSB reactor,aerobic SBR reactor,autotrophic nitrogen removal SBBR reactor and anaerobic ammonium oxidation EGSB reactor.Phospholipid extracts of sludge were detected by the HPLC-ESI-MS/MS method to determine the types of intact ladderane lipids,and the specificity of intact ladderane lipids was also analyzed,at the same time,the bacterial community structure of autotrophic nitrogen removal SBBR reactor and anaerobic ammonium oxidation EGSB reactor was determined by high-throughput sequencing technology.Analytical results of intact ladderane lipids showed that intact ladderane lipids were not detected from anaerobic EGSB reactor and aerobic SBR reactor,and were detected from autotrophic nitrogen removal SBBR reactor and anaerobic ammonium oxidation EGSB reactor.Five kinds of intact ladderane lipids were detected in the phospholipid extract of sludge from autotrophic nitrogen removal SBBR reactor,and seven kinds of intact ladderane lipids were detected in the phospholipid extract of sludge from anaerobic ammonium oxidation EGSB reactor.The results of high-throughput sequencing confirmed that the autotrophic nitrogen SBBR reactor contained AnAOB of the genera Candidatus Brocadia and Candidatus Jettenia,and the anaerobic ammonium oxidation EGSB reactor contained AnAOB of the genera Candidatus Kuenenia and Candidatus Jettenia.These results illustrated that intact ladderane lipids were the peculiar phospholipids in AnAOB.
Keywords: AnAOB; high-throughput sequencing; intact ladderane lipids; phospholipid; reactor.