Average microbial (bacterial and archaeal) community composition of groundwater sampled in Auckland.

These results were determined by sequencing bacterial and archaeal 16S rRNA phylogenetic marker genes.

Bacteria, particularly Proteobacteria, dominate these groundwaters. Proteobacteria are a large phylum of gram-negative bacteria that have diverse metabolisms and are found within many environments. Numerous members are capable of metabolising and transforming nitrogen.

Facts about Bacteroidetes

Members of this phylum are metabolically diverse.

Some members breakdown complex organic carbon, while others metabolise nitrogen, transforming it into various forms, such as ammonium or N2 gas.

As ammonium, nitrogen is retained in groundwater, where it remains available as a nutrient for other organisms.

As N2 gas, it is returned to the atmosphere, and no longer accessible.