Rapid evolution in necromass use under resource limitation reduces persistence in producer-decomposer microbial biospheres
This study employs a synthetic microbial biosphere model to investigate system persistence under resource limitation. Escherichia coli (E. coli) strain MC4100 was incubated in matter-closed systems in an isotonic saline solution without added nutrients for 60 days in spatially homogeneous or heterogeneous conditions. We observed phenotypic adaptive changes in E. coli populations, including loss of motility, enhanced biofilm formation, and improved growth on various carbon sources, which were specific to the spatial structure conditions. While these changes were beneficial for E. coli persistence in monoculture, during co-culture with the alga Chlamydomonas reinhardtii the adapted populations exhibited a 25% reduction in persistence under spatially heterogeneous conditions compared to co-cultures containing non-adapted E. coli populations. Critically, adaptive changes in monoculture affected the dynamics of co-cultures, demonstrating that microbial evolution can constrain coexistence with other species and may be a fundamental determinant of ecosystem sustainability.