Diverse bacteria exhibit superadditive growth on mixed classes of carbon sources

Diverse bacteria have been observed to demonstrate superadditive growth when exposed to a mixture of functionally-distinct carbon sources, according to a recent study. This finding sheds light on the potential benefits of such bacterial diversity in natural environments. Researchers grew dozens of strains from four different phyla on defined mixtures representing five classes of carbon sources, and discovered that many of these strains exhibited growth that exceeded the expected sum of growth on more concentrated subsets of similar compounds.

Further investigation into the underlying mechanisms revealed that superadditive growth was associated with enhanced carbon consumption in the mixed-class medium. Importantly, this growth was also accompanied by a reduced dependence on amino acid and nucleotide biosynthesis. The researchers used exometabolomics, pooled genetic screens, and proteomics to arrive at these conclusions.

Notably, superadditive growth could be predicted based on the genomes of the tested strains, and was correlated with a genomically encoded preference for sugar over acid. These results highlight a previously unrecognized aspect of physiological variation among heterotrophs, and open up new avenues for understanding the biochemical and evolutionary basis of this diversity.