Complete Genomes of the Anaerobic Degradation Specialists <b><i>Aromatoleum petrolei</i></b> ToN1^T and <b><i>Aromatoleum bremense</i></b> PbN1^T

Abstract

The betaproteobacterial genus &lt;i&gt;Aromatoleum&lt;/i&gt; comprises facultative denitrifiers specialized in the anaerobic degradation of recalcitrant organic compounds (aromatic and terpenoid). This study reports on the complete and manually annotated genomes of &lt;i&gt;Ar. petrolei&lt;/i&gt; ToN1&lt;sup&gt;T&lt;/sup&gt; (5.41 Mbp) and &lt;i&gt;Ar. bremense&lt;/i&gt; PbN1&lt;sup&gt;T&lt;/sup&gt; (4.38 Mbp), which cover the phylogenetic breadth of the genus &lt;i&gt;Aromatoleum&lt;/i&gt; together with previously genome sequenced &lt;i&gt;Ar. aromaticum&lt;/i&gt; EbN1&lt;sup&gt;T&lt;/sup&gt; [Rabus et al., Arch Microbiol. 2005 Jan;183(1):27–36]. The gene clusters for the anaerobic degradation of aromatic and terpenoid (strain ToN1&lt;sup&gt;T&lt;/sup&gt; only) compounds are scattered across the genomes of strains ToN1&lt;sup&gt;T&lt;/sup&gt; and PbN1&lt;sup&gt;T&lt;/sup&gt;. The richness in mobile genetic elements is shared with other &lt;i&gt;Aromatoleum&lt;/i&gt; spp., substantiating that horizontal gene transfer should have been a major driver in shaping the genomes of this genus. The composite catabolic network of strains ToN1&lt;sup&gt;T&lt;/sup&gt; and PbN1&lt;sup&gt;T&lt;/sup&gt; comprises 88 proteins, the coding genes of which occupy 86.1 and 76.4 kbp (1.59 and 1.75%) of the respective genome. The strain-specific gene clusters for anaerobic degradation of ethyl-/propylbenzene (strain PbN1&lt;sup&gt;T&lt;/sup&gt;) and toluene/monoterpenes (strain ToN1&lt;sup&gt;T&lt;/sup&gt;) share high similarity with their counterparts in &lt;i&gt;Ar. aromaticum&lt;/i&gt; strains EbN1&lt;sup&gt;T&lt;/sup&gt; and pCyN1, respectively. Glucose is degraded via the ED-pathway in strain ToN1&lt;sup&gt;T&lt;/sup&gt;, while gluconeogenesis proceeds via the reverse EMP-pathway in strains ToN1&lt;sup&gt;T&lt;/sup&gt;, PbN1&lt;sup&gt;T&lt;/sup&gt;, and EbN1&lt;sup&gt;T&lt;/sup&gt;. The diazotrophic, endophytic lifestyle of closest related genus &lt;i&gt;Azoarcus&lt;/i&gt; is known to be associated with nitrogenase and type-6 secretion system (T6SS). By contrast, strains ToN1&lt;sup&gt;T&lt;/sup&gt;, PbN1&lt;sup&gt;T&lt;/sup&gt;, and EbN1&lt;sup&gt;T&lt;/sup&gt; lack &lt;i&gt;nif&lt;/i&gt; genes for nitrogenase (including cofactor synthesis and enzyme maturation). Moreover, strains PbN1&lt;sup&gt;T&lt;/sup&gt; and EbN1&lt;sup&gt;T&lt;/sup&gt; do not possess &lt;i&gt;tss&lt;/i&gt; genes for T6SS, while strain ToN1&lt;sup&gt;T&lt;/sup&gt; does and facultative endophytic “&lt;i&gt;Aromatoleum&lt;/i&gt;” sp. CIB is known to even have both. These findings underpin the functional heterogeneity among &lt;i&gt;Aromatoleum&lt;/i&gt; members, correlating with the high plasticity of their genomes.

IncP‐type plasmids carrying genes for antibiotic resistance or for aromatic compound degradation are prevalent in sequenced Aromatoleum and Thauera strains

“…aromaticum EbN1 T and Ar. bremense PbN1 T (92%–99.8% identity; Weiten et al, 2021), suggesting a common evolutionary history of the plasmids in the genus Aromatoleum .…”

Evaluation of the plant biostimulant effects of selected eukaryotic green microalgae

“…Aromateleum petrolei, a closely related species, was ten times more prevalent in control samples than in MA-treated samples. This species and its relatives can cause anaerobic degradation of resistant organic compounds, such as aromatic and terpenoid compounds (Weiten et al, 2021). Azoarcus and Aromateleum are both anaerobic degradation specialists that degrade organic molecules that are typically conversion products in anaerobic conditions.…”