Effect of hyphal micromorphology on bioreactor performance of antibiotic-producing Saccharopolyspora erythraea cultures

When Saccharopolyspora erythraea biomass from submerged culture was filtered (100-120 mu m sintered glass filter) the antibiotic yield of the retentate (mean hyphal particle diameter 103 mu m) was significantly higher [1.740 mg (mg biomass)(-1)] than that of the filtrate [1.286 mg (mg biomass)(-1); mean hyphal particle diameter 88 mu m], A hypothesis to explain this is that there is a critical hyphal particle diameter, below which the particle is incapable of producing antibiotic. This would be a consequence of the site of antibiotic production occurring at a fixed distance from the growing hyphal tip. A protocol is proposed for calculation of the hypothetical critical hyphal diameter (88 mu m in this case), The proportion of retentate (more productive) fraction of biomass varied between 60% and 30% during the course of a batch culture, Bioreactor stirrer speed significantly affected mean hyphal particle diameter (70 mu m at 1500 r,p,m,; 124 mu m at 750 r,p,m,) and antibiotic productivity [0.867 mg (mg biomass)(-1) at 1500 r,p,m.; 0.913 mg (mg biomass)(-1) at 750 r.p.m.].