Drawing up a collaborative contract: Amino acid cross-feeding between
inter-species bacterial pairs
Abstract
Synthetic microbial communities have the potential to enable new
platforms for bioproduction of biofuels and biopharmaceuticals. However,
using engineered communities is often assumed to be difficult because of
anticipated challenges in establishing and controlling community
composition. Cross-feeding between microbial auxotrophs has the
potential to facilitate co-culture growth and stability through a
mutualistic ecological interaction. We assessed cross-feeding between 13
Escherichia coli amino acid auxotrophs paired with a leucine
auxotroph of Bacillus megaterium. We developed a minimal media
capable of supporting the growth of both bacteria and used the media to
study co-culture growth of the 13 interspecies pairs of auxotrophs in
batch and continuous culture, and on semi-solid media. In batch culture,
eight of thirteen pairs of auxotrophs were observed to grow in
co-culture. We developed a new metric to quantify the impact of
cross-feeding on co-culture growth. Six pairs also showed long-term
stability in continuous culture, where co-culture growth at different
dilution rates highlighted differences in cross-feeding amongst the
pairs. Finally, we found that cross-feeding-dependent growth on
semi-solid media is highly stringent and enables identification of the
most efficient pairs. These results demonstrate that cross-feeding is a
viable approach for controlling community composition within diverse
synthetic communities.