Hydrodynamic Effects on Biofilm Development and Recombinant Protein Expression

Area of Science:

• Biotechnology
• Microbiology
• Biochemical Engineering

Background:

• Hydrodynamics significantly influence cell attachment, nutrient/oxygen transfer, and biofilm development.
• Biofilm characteristics directly impact recombinant protein production efficiency.
• Understanding flow effects is crucial for optimizing bioprocesses.

Purpose of the Study:

• To investigate the impact of varying hydrodynamic conditions on Escherichia coli biofilm formation.
• To assess the effect of flow rates on the expression of enhanced green fluorescent protein (eGFP) in biofilms.
• To determine the relationship between flow velocity and plasmid copy number in planktonic and biofilm cells.

Main Methods:

• Culturing Escherichia coli planktonic and biofilm cells in a recirculating flow cell system for 7 days.
• Applying two distinct flow rates: 255 L h⁻¹ (Re=4600) and 128 L h⁻¹ (Re=2300).
• Utilizing fluorometric analysis to quantify eGFP production and flow cytometry for eGFP-expressing cell percentage and plasmid copy number (PCN).

Main Results:

• Specific eGFP production was significantly higher in biofilms compared to planktonic cells (3-fold at 255 L h⁻¹, 2-fold at 128 L h⁻¹).
• The percentage of eGFP-expressing cells in biofilms increased by 52% at the higher flow rate (255 L h⁻¹).
• Higher flow velocity led to increased plasmid copy number in both planktonic and biofilm cells.

Conclusions:

• Elevated flow velocities positively correlate with enhanced eGFP expression in Escherichia coli biofilms.
• Hydrodynamic conditions are a critical factor in optimizing recombinant protein yields from bacterial biofilms.
• The study highlights the potential of manipulating flow rates to improve biotechnological applications using engineered biofilms.