TY - JOUR
T1 - Exploring the onset of B12-based mutualisms using a recently evolved Chlamydomonas auxotroph and B12-producing bacteria
AU - Bunbury, Freddy
AU - Deery, Evelyne
AU - Sayer, Andrew P.
AU - Bhardwaj, Vaibhav
AU - Harrison, Ellen L.
AU - Warren, Martin J.
AU - Smith, Alison G.
N1 - Funding Information: This work was supported by: the UK's Biotechnology and Biological Sciences Research Council (BBSRC) Doctoral Training Partnership (grant no. BB/M011194/1) to F.B., A.P.S. and A.G.S.; BBSRC grant (BB/S002197/1) to M.J.W. and E.D.; the Gates Cambridge Trust (PhD scholarship to V.B.); the MELiSSA Foundation (FB European Space Agency) (grant no. CO-90-16-4078-02) to A.G.S. and E.H.
Acknowledgements: The authors are grateful for helpful discussions with Dr Payam Mehrshahi and Dr Katrin Geisler (University of Cambridge) and Dr Katherine Helliwell (Marine Biological Association of the UK) and technical support from Geraldine Heath and Lorraine Archer.
PY - 2022/7
Y1 - 2022/7
N2 - Cobalamin (vitamin B12) is a cofactor for essential metabolic reactions in multiple eukaryotic taxa, including major primary producers such as algae, and yet only prokaryotes can produce it. Many bacteria can colonize the algal phycosphere, forming stable communities that gain preferential access to photosynthate and in return provide compounds such as B12. Extended coexistence can then drive gene loss, leading to greater algal–bacterial interdependence. In this study, we investigate how a recently evolved B12-dependent strain of Chlamydomonas reinhardtii, metE7, forms a mutualism with certain bacteria, including the rhizobium Mesorhizobium loti and even a strain of the gut bacterium E. coli engineered to produce cobalamin. Although metE7 was supported by B12 producers, its growth in co-culture was slower than the B12-independent wild-type, suggesting that high bacterial B12 provision may be necessary to favour B12 auxotrophs and their evolution. Moreover, we found that an E. coli strain that releases more B12 makes a better mutualistic partner, and although this trait may be more costly in isolation, greater B12 release provided an advantage in co-cultures. We hypothesize that, given the right conditions, bacteria that release more B12 may be selected for, particularly if they form close interactions with B12-dependent algae.
AB - Cobalamin (vitamin B12) is a cofactor for essential metabolic reactions in multiple eukaryotic taxa, including major primary producers such as algae, and yet only prokaryotes can produce it. Many bacteria can colonize the algal phycosphere, forming stable communities that gain preferential access to photosynthate and in return provide compounds such as B12. Extended coexistence can then drive gene loss, leading to greater algal–bacterial interdependence. In this study, we investigate how a recently evolved B12-dependent strain of Chlamydomonas reinhardtii, metE7, forms a mutualism with certain bacteria, including the rhizobium Mesorhizobium loti and even a strain of the gut bacterium E. coli engineered to produce cobalamin. Although metE7 was supported by B12 producers, its growth in co-culture was slower than the B12-independent wild-type, suggesting that high bacterial B12 provision may be necessary to favour B12 auxotrophs and their evolution. Moreover, we found that an E. coli strain that releases more B12 makes a better mutualistic partner, and although this trait may be more costly in isolation, greater B12 release provided an advantage in co-cultures. We hypothesize that, given the right conditions, bacteria that release more B12 may be selected for, particularly if they form close interactions with B12-dependent algae.
UR - http://www.scopus.com/inward/record.url?scp=85130438601&partnerID=8YFLogxK
U2 - 10.1111/1462-2920.16035
DO - 10.1111/1462-2920.16035
M3 - Article
C2 - 35593514
AN - SCOPUS:85130438601
SN - 1462-2912
VL - 24
SP - 3134
EP - 3147
JO - Environmental Microbiology
JF - Environmental Microbiology
IS - 7
ER -