The nitrite-oxidizing community in activated sludge from a municipal wastewater treatment plant determined by fatty acid methyl ester-stable isotope probing.
Metabolically-active autotrophic nitrite oxidizers from activated sludge were labeled with (13)C-bicarbonate under exposure to different temperatures and nitrite concentrations. The labeled samples were characterized by FAME-SIP (fatty acid methyl ester-stable isotope probing). The compound cis-11-palmitoleic acid, which is the major lipid of the most abundant nitrite oxidizer in activated sludge, Candidatus Nitrospira defluvii, showed (13)C-incorporation in all samples exposed to 3 mM nitrite. Subsequently, the lipid cis-7-palmitoleic acid was labeled, and it indicated the activity of a nitrite oxidizer that was different from the known Nitrospira taxa in activated sludge. The highest incorporation of cis-7-palmitoleic acid label was found after incubation with a nitrite concentration of 0.3 mM at 17 and 22°C. While activity of Nitrobacter populations could not be detected by the FAME-SIP approach, an unknown nitrite oxidizer with the major lipid cis-9 isomer of palmitoleic acid exhibited (13)C-incorporation at 28°C with 30 mM nitrite. These results indicated flexibility of nitrite-oxidizing guilds in a complex community responding to different conditions. Labeled lipids so far not described for activated sludge-associated nitrifiers indicated the presence of unknown nitrite oxidizers in this habitat. The FAME-SIP-based information can be used to define appropriate conditions for the enrichment of nitrite-oxidizing guilds from complex samples.
Rheinische Friedrich-Wilhelms-Universität Bonn, Institut für Ernährungs- und Lebensmittelwissenschaften, Abteilung Lebensmittelmikrobiologie und -hygiene, Meckenheimer Allee 168, 53115 Bonn, Germany.
Myriam
M
Kruse
Sabine
S
Zumbrägel
Evert
E
Bakker
Eva
E
Spieck
Till
T
Eggers
André
A
Lipski
D001419:Bacteria / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004952:Esters / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D007553:Isotope Labeling; D008969:Molecular Sequence Data; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater / Q000382:microbiology*
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004952:Esters; D005227:Fatty Acids; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D062065:Wastewater
Activated sludge; ECL; FAME-SIP; FISH; GC–MS; HPLC; Metabolic activity; NOB; Nitrite-oxidizing bacteria; Nitrospira; PLFA; SIM; T-RFLP; equivalent chain lengths; fatty acid methyl ester-stable isotope probing; fluorescence in situ hybridization; gas chromatography coupled with mass spectrometry; high performance liquid chromatography; nitrite-oxidizing bacteria; phospholipid fatty acid; single ion monitoring; terminal restriction fragment length polymorphism