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#exponential phase

2 public questions tagged with this topic.

Animal Tissue Culture 3

The phase of cell growth most suitable for drug testing is:

Pharmacological testing and chemosensitivity evaluation are most predictive during logarithmic exponential growth phase when cell population is actively cycling, metabolically robust, and homogeneous. During lag, cells are still recovering and fraction in S phase low, causing underestimation of antimetabolite efficacy. In log phase, DNA synthesis enzymes including topoisomerase II, thymidylate synthase, and kinases targeted by many drugs are highly expressed, mitochondrial activity high, ATP levels stable. Dose-response curves generated in this window show reproducible IC50 values. Plateau or

Ref: Freshney Ch.21 Drug testing log phase; NIH Assay Guidance Manual 2021 Chemosensitivity assays log phase optimal viability.

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Microbial Physiology

Which phase of bacterial growth is best suited for industrial fermentation?

Industrial fermentation aims to maximize volumetric productivity of biomass, recombinant proteins or primary metabolites in minimal time with reproducible quality. Log phase cells are physiologically most uniform population with high ribosome content, active glycolysis and TCA cycle, abundant ATP and NADPH and low stringent response. Enzyme systems for substrate uptake like PTS and product synthesis operate at peak specific activity providing fastest conversion per cell per hour. Transferring mid-exponential inoculum into production vessel shortens nonproductive lag phase improving batch turna

Ref: Lodish et al., Molecular Cell Biology, 8th ed., Chapter 12: Log Phase for Industrial Fermentation and Biomass Production.

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