Compare L-lysine, Penicillin and Erythropoietin with Respect to Harvest Timing, Process Type and Production Strategy

Name a primary metabolite, a secondary metabolite, and a recombinant protein, respectively

. L-lysine, penicillin and erythropoietin (EPO)

What areas do they differ

microbial growth, regulation, and stability, and therefore requires different fermentation strategies and harvest timings

L - product type and metabolism

L-lysine is a primary metabolite, meaning it is essential for normal cellular growth and metabolism. It is therefore growth-associated and produced during active cell division.

L production characteristics

• Produced by bacteria such as Corynebacterium glutamicum

• Production occurs mainly during the exponential growth phase

• Cellular control systems are manipulated to increase pathway flux

L - harvesting time

Because lysine production is linked directly to growth:

• Fermentation is harvested at the end of exponential phase or early stationary phase

• Harvesting later reduces productivity as growth slows

L - process strategy

• Typically produced in batch fermentation

• Requires good aeration and control of pH and nutrients

• High volumetric productivity is achieved by maximising growth rate

P - production type and metabolism

Penicillin is a secondary metabolite and is not required for growth. It is produced only after growth has slowed, often as a response to nutrient limitation or stress.

P - production characteristics

• Produced by the fungus Penicillium chrysogenum

• Biomass formation occurs first as fungus grows and accumulates mycelial mass.

• Penicillin synthesis begins during the stationary phase

P - harvesting timing

Because penicillin is non-growth-associated:

• Fermentation is harvested late in stationary phase

• Harvesting too early results in very low antibiotic yield

P - process strat

• Usually produced in batch or fed-batch culture

• Media are designed to:

  • support initial growth

  • then limit nutrients to trigger secondary metabolism

E - product type and metabolism

Erythropoietin is a recombinant protein. It is not naturally produced by the host organism and is synthesised following genetic modification.

E - production characteristics

• Produced in eukaryotic systems to allow correct protein folding and glycosylation

• Expression is often induced at a specific stage of growth

• Product stability is a major concern

E - Harvesting time

Harvest timing balances:

• maximum expression

• avoidance of protein degradation

Typically:

• Harvest occurs in late exponential or early stationary phase

• Before prolonged stationary phase causes cell stress or lysis

E - process strat

• Tight control of conditions

• Emphasis on product quality rather than maximum growth

• Downstream processing is critical and costly due to high purity requirements