Genomic insights into metabolic potentials of two simultaneous aerobic denitrification and phosphorus removal bacteria Achromobacter sp. GAD3 and Agrobacterium sp. LAD9

Abstract

Bacteria capable of simultaneous aerobic denitrification and phosphorus removal (SADPR) are promising to establish novel one-stage wastewater treatment systems. Nevertheless, insights into metabolic potentials of SADPR related bacteria are limited. Here, comprehensive metabolic models of two efficient SADPR bacteria Achromobacter sp. GAD3 and Agrobacterium sp. LAD9 were yielded for the first time by high-throughput genome sequencing. With succinate as the preferred carbon source, both strains employed a complete TCA cycle as the major carbon metabolism for various organic acids and complex carbon oxidation potentials. Complete and truncated aerobic denitrification routes were confirmed in GAD3 and LAD9, respectively, facilitated by all major components of electron transfer chain via oxidative phosphorylation. Comparative genome analysis revealed distinctive ecological niches involved in denitrifying potential among different phylogenetic clades within Achromobacter and Agrobacterium. Excellent phosphorus removal capacities were contributed by inorganic phosphate uptake, polyphosphate synthesis and phosphonate metabolism. Additionally, the physiology of GAD3/LAD9 is different to that displayed by most available polyphosphate accumulating organisms (PAOs), and reveals both strains to be more versatile, carrying out diverse organics degradation potentials and outstanding SADPR capacity within a single organism. The functional explorations of SADPR bacteria broaden their significant application prospects in concurrent carbon and nutrients removal aerobically.

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