Production of rhamnolipid biosurfactants in solid-state fermentation: process optimization and characterization...

Area of Science:

• Microbiology
• Biotechnology
• Biochemistry

Background:

• Rhamnolipids are extracellular biosurfactants produced by Pseudomonas species.
• They have diverse environmental and industrial applications.
• Agro-industrial residues offer potential for sustainable biosurfactant production.

Purpose of the Study:

• To identify and optimize key process parameters for rhamnolipid synthesis by Pseudomonas aeruginosa PTCC 1074s.
• To utilize soybean meal as a substrate in solid-state fermentation for enhanced rhamnolipid production.

Main Methods:

• Fractional factorial design was employed to screen nutritional and environmental parameters.
• Response surface methodology was utilized to optimize significant factors.
• Biosurfactant characterization included TLC, FT-IR, and H-NMR analysis.

Main Results:

• Optimal conditions (34.5°C, 80% humidity, 1.4 mL inoculum, 5% glycerol) yielded 19.68 g/kg dry substrate of rhamnolipids.
• The biosurfactant reduced water's surface tension from 71.8 to 32.2 mN/m.
• The rhamnolipid exhibited stability across a broad range of pH, temperature, and NaCl concentrations.

Conclusions:

• Agro-industrial residues, like soybean meal, show significant potential for rhamnolipid production.
• Optimization of process parameters enhances rhamnolipid yield.
• This study validates the use of sustainable substrates for biosurfactant manufacturing.