Impact of carbon and nitrogen conditions on E-coli surface thermodynamics

Escherichia coli cultured under different carbon and nitrogen conditions was measured for growth and surface thermodynamics to examine the impact of C/N ratio on E coli growth and its surface thermodynamics. Among the three carbon sources, glucose grown cultures had the greatest specific growth rate (0.67 and 0.44 h(-1) with ammonia and nitrate serving as the nitrogen source, respectively. and no carbon or nitrogen limitation), and yielded the least hydrophilic surface (31.49 and 22.23 mJ m(-2) of the total interfacial free energy of interaction); propionate grown cultures had the greatest stoichiometric yield coefficient (0.61 and 0.49 g biomass per g substrate), lipopolysaccharide production efficiency (0.161 and 0.149 g per g biomass), and yielded the most hydrophilic surface (46.32 and 39.32 mJ m(-2) of the total interfacial free energy of interaction). For the same carbon source, ammonia-grown cultures yielded a greater specific growth rate, growth yield and lipopolysaccharide production efficiency, and a more hydrophilic surface than nitrate grown cultures. In carbon-limited cultures, a smaller specific growth rate and lipopolysaccharide production efficiency and greater growth yield were observed as compared with cultures grown with no carbon and nitrogen limitation. In addition, under carbon-limited growth, the cells exhibited a less hydrophilic surface. When nitrogen was the limiting factor. E coli displayed a smaller specific growth rate and growth yield, greater lipopolysaccharide production efficiency and a more hydrophilic surface as compared with cultures grown with no carbon and nitrogen limitation. (C) 2002 Elsevier Science B.V. All rights reserved.