Publications

4561

A novel anaerobic ammonium-oxidizing (anammox) bacterium was detected in an upflow column reactor treating synthetic nitrogen-rich saline solution. Here, we assembled a 4.59-Mb draft genome sequence of this bacterium, identified as a member of the genus “ Candidatus Scalindua,” that has 84% nucleotide-level genomic similarity with the closest related anammox bacterium (“ Candidatus Scalindua rubra”).

“ Candidatus Serratia symbiotica” is a facultative bacterial symbiont of aphids that affects various ecological traits of the host insects. Here, we report the complete genome sequence of “ Candidatus Serratia symbiotica” strain IS, consisting of a 2,736,352-bp chromosome and an 82,605-bp plasmid, from the pea aphid Acyrthosiphon pisum .

‘ Candidatus Liberibacter asiaticus’ ( CL as) is associated with the most destructive disease of citrus, huanglongbing ( HLB ). The most widely used methods for detection of CL as are PCR ‐based and require purification of DNA from plant samples. Elution of DNA from tissue prints made on nitrocellulose membranes followed by qPCR ( TPE ‐ qPCR ) was compared to DNA extraction of plant tissue followed by PCR (X‐ PCR ) by testing the same tissue samples. The former estimated a higher CL as population in tissue prints than the latter ( t ‐test; P  =   0.009). All extracts prepared for TPE ‐ qPCR throughout the experiment were also tested by conventional PCR and 80.8% were identified as positive. A similar set of stem and petiole tissue samples was tested by TPE ‐ qPCR and immunoassay. Although the detection rate by TPE ‐ qPCR was higher than by immunoassay, about 6% of tissue prints were positive by immunoassay but not by TPE ‐ qPCR . Thus, a higher detection rate would be achieved by combining TPE ‐ qPCR with immunoassay. Significant differences were observed in the performance of nitrocellulose membranes from different manufacturers in these assays. Immunotissue prints showed that the spatial distribution pattern of CL as infection varied widely from one sample to another, but the patterns were highly correlated among serial sections from the same sample, suggesting that CL as preferentially colonizes adjacent phloem cells in a vertical rather than horizontal direction.

“ Ca. Nitrotoga” is a NOB of high environmental relevance, but physiological data exist for only a few representatives. Initially, it was detected in specialized niches of low temperature and low nitrite concentrations, but later on, its ubiquitous distribution revealed its critical role for N removal in engineered systems like WWTPs. In this study, we analyzed the competition between Nitrotoga and Nitrospira in bioreactors and identified conditions where the K strategist Ns. defluvii was almost replaced by Nitrotoga sp. BS. We show that the pH value is an important factor that regulates the composition of the nitrite-oxidizing enrichment with a dominance of Nitrotoga sp. BS versus Ns. defluvii at a neutral pH of 7.4 in combination with a temperature of 17°C. The physiological diversity of novel Nitrotoga cultures improves our knowledge about niche differentiation of NOB with regard to functional nitrification under suboptimal conditions.