Microorganisms generation time

The mechanisms of resistance can vary. In bacterial resistance to antibiotics, these include pumping the antibiotic out of the cell, changing the cell wall to avoid the antibiotic, enzymatic destruction of the antibiotic, and the development of substitute proteins not targeted by the antibiotic.24 It may take longer to develop resistance in insects and plants than in microorganisms simply because the generation times are longer. 

These predictions are most easily tested in cultures of microorganisms because of the short generation time and the ease of manipulation of culture parameters. In the light of the present hypothesis it is hardly surprising that many bacteria cultured under optimum growth conditions express no or insignificant amounts of secondary... 

It remains an open question how the microorganisms in subsurface sediments are able to survive on the extremely low energy and carbon flux available for each cell. By DNA/RNA based techniques it could be shown that a significant fraction of the bacteria are alive and active rather than dormant or even dead (Schippers et al. 2005). Yet, calculations from cell numbers and measured or modeled mineralization rates show that the organic carbon flux available in million year old sediments allows only generation times of years to thousands of years (Whitman et al. 1998 Schippers et al. 2005). 

Temperature influences the growth rate of all microorganisms. As with chemical reactions, it accelerates biochemical reactions. Cellular activity (resulting from all of the involved enzyme activities) and consequently growth vary with temperature according to a bell curve. At the optimum temperature, generation time is the quickest. This curb not only varies with the species and strains but also with the environment in which the bacteria multiply. 

Estimate the food-microorganism ratio (F/M) and sludge age (solid retention time) of an activated sludge process designed to reduce the BOD5 of the spent stream generated from a biological production plant from 1500 mg/L to 50 mg/L. The wastewater flow is Q = 15,000 GPD, aeration tank volume = 45 m, MLVSS = 3000 mg/L, and net biomass yield coefficient (Tn) = 0.28 kg/kg. Also compute the performance efficiency of the plant. 

---