Figure 1
Morphology and in situ detection of N. hollandicus. (a) Phase contrast micrograph of an autotrophically grown pure culture. (b) Transmission electron micrograph of cells from the same culture as in panel a. (c) In situ detection of N. hollandicus and AOB in activated sludge from the bioreactor that was the source of the isolated N. hollandicus strain. The populations were detected by FISH using the probes Ntlc804 (specific for N. hollandicus), Cluster6a192 (specific for AOB of the N. oligotropha lineage) and the EUB338 probe mix targeting most Bacteria. Cells of N. hollandicus appear magenta, AOB green-blue and other bacteria dark blue. (d) Thin section electron micrograph of a cell from a culture that was grown mixotrophically in medium containing NO2−, HCO3/CO2 and formate. The layered cell envelope is clearly visible. N, nucleoide; CW-EL, external layer of the cell wall; CW-PG, peptidoglycane; CM, cytoplasmic membrane.
