In a chemostat operating under steady state, a bacterial culture can be grown at a dilution rate higher than maximum growth rate by (A) partial cell recycling (B) using sub-optimal temperature (C) pH cycling (D) substrate feed rate cycling

Answer: (A) partial cell recycling
In a chemostat, partial cell recycling allows the culture to maintain a higher dilution rate than the maximum growth rate by retaining some of the biomass, effectively increasing the total biomass concentration and extending the effective growth rate of the culture. Other options do not typically achieve this.