Cultivation And Genomics Of Members Of Group 4 Aigarchaeota

Event Center BC

Aigarchaeota is a deeply branching, thermophilic clade within in the domain Archaea that has no cultivated representatives. Based on 16s rRNA phylogenies, 9 genus level groups have been identified within Aigarchaeota. This work is part of a larger project focusing on one of these groups, Group 4 Aigarchaeota (Aig G4), with the following goals: definition and analysis of an Aig G4 metagenome bin, and testing genomics-based predictions on laboratory enrichment cultures of Aig G4. Aig G4 was found to be relatively abundant in in situ lignocellulose (corn stover) enrichments established at ~85 °C in Great Boiling Spring (GBS), NV. A metagenome derived from the GBS in situ enrichments, yielded an Aig G4 metagenome bin of ~1.48 Mb in size, and an estimated completeness of 90%. Maximum likelihood phylogenomic analysis confirmed that the selected bin from the metagenome does represent a member of Aigarchaeota. Annotation of the Aig G4 genome was done using RAST sequence database, and BLAST to compare the percent homology between AigG4 protein sequences to functional proteins identified in other archaea. From the annotation, genes to complete glycolysis and further processing of pyruvate to acetate or ethanol were identified. Genes involved in the catabolism of amino acids were found, but several genes in known amino acid catabolic pathways are missing. Tungsten aldehyde oxidoreductases (AOR) and a tungsten specific ABC transporter were identified, which may participate in sugar or amino acid catabolism. Enrichment cultures containing Aig G4 have been established in the laboratory, and were used to test various genomicsbased predictions. Aig G4 can be grown in semisynthetic media containing GBS spring water and the major growth substrate cornstover, but growth and long-term maintenance is not observed in synthetic medium containing corn stover, suggesting that a in GBS water, resulted in consistent growth of Aig G4 at levels comparable to cultures grown on semi-synthetic medium. This suggests that tungsten may be an important trace nutrient for Aig G4, as predicted by the presence of the tungsten containing AOR, and that these genes may be critical for Aig G4 metabolism. Future experiments on these laboratory cultures will be used to determine what other component(s) of GBS spring water is useful to Aig G4 and to determine the role of tungsten AOR in Aig G4 metabolism. Stable isotope probing will also be employed to determine whether Aig G4 can use sugars and/or amino acids as growth substrates and carbon sources.