Sporulation at minimum specific growth rate in Aspergillus nidulans chemostat culture predicted using protein synthesis efficiency estimations.
Ribosomal efficiency (RE) estimates provide a quantitative descriptor of intrinsic growth rate of cell populations using readily-obtainable experimental data. In Aspergillus nidulans chemostat cultures, RE increased linearly with growth rate over the range 25-60% of maximum growth rate (mu max), consistent with increasing ribosomal usage with increased growth rate. Above 60%, RE did not increase significantly, suggesting that all ribosomes were functional at 60% of mu max, further increases in growth rate, presumably resulting from increased polypeptide chain elongation rate. Extrapolating the linear part of the RE/growth rate curve predicted zero RE at a growth rate of 0.04 h-1. Chemostat steady state cultures at 0.04 h-1 contained spores (conidia), apparently undergoing a continuous sporulation/germination cycle. We propose that the RE estimates provide a means of predicting the value of minimum specific growth rate (mu min) below which net growth cannot take place.
Bushell
M E
ME
Microbial Products Laboratory, School of Biological Sciences, University of Surrey, Guildford, UK.
Bull
A T
AT
D001233:Aspergillus nidulans / Q000378:metabolism / Q000502:physiology*; D019149:Bioreactors; D003470:Culture Media; D005656:Fungal Proteins / Q000096:biosynthesis*; D008856:Microscopy, Fluorescence; D012331:RNA, Fungal / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D013172:Spores, Fungal / Q000502:physiology
D003470:Culture Media; D005656:Fungal Proteins; D012331:RNA, Fungal