Strategic traits of bacteria and archaea vary widely within substrate use groups.

Abstract

Quantitative traits such as maximum growth rate and cell radial diameter are one facet of ecological strategy variation across bacteria and archaea. Another facet is substrate-use pathways, such as iron reduction or methylotrophy. Here we ask how these two facets intersect, using a large compilation of data for culturable species and examining seven quantitative traits (genome size, signal-transduction protein and histidine kinase counts, growth temperature, temperature adjusted maximum growth rate, cell radial diameter, and 16S rRNA operon copy number). Overall, quantitative trait variation within groups of organisms possessing a particular substrate-use pathway was very broad, outweighing differences between substrate-use groups. Although some substrate-use groups had significantly different means for some quantitative traits, standard deviation of quantitative trait values within each substrate use pathway mostly averaged between 1.6 and 1.8 times larger than standard deviation across group means. Most likely this wide variation reflects ecological strategy: for example, fast maximum growth rate is likely to express an early-successional or copiotrophic strategy, and maximum growth varies widely within most substrate-use pathways. In general, it appears that these quantitative traits express different and complementary information about ecological strategy, compared to substrate use.