Maximize rhamnolipid production with low foaming and high yield

Area of Science:

• Microbiology
• Biotechnology
• Biochemical Engineering

Background:

• Rhamnolipids are microbial surfactants with diverse applications.
• High production costs due to foaming, low productivity, and yield limit rhamnolipid applications.
• Optimization of fermentation parameters is crucial for cost-effective rhamnolipid production.

Purpose of the Study:

• To optimize fermentation parameters (dissolved oxygen, pH, carbon source) for enhanced rhamnolipid production.
• To investigate the impact of different carbon sources (glycerol vs. soybean oil) on rhamnolipid productivity, yield, and composition.
• To mitigate foaming issues associated with aerobic rhamnolipid fermentation.

Main Methods:

• Fermentation optimization by adjusting dissolved oxygen (DO) and pH levels.
• Comparative analysis of glycerol and soybean oil as carbon sources for Pseudomonas aeruginosa.
• Analysis of rhamnolipid composition using liquid chromatography-mass spectrometry (LC-MS).

Main Results:

• Optimal conditions identified as 10% DO and pH 5.5-5.7, balancing growth, production, and foam control.
• Soybean oil significantly outperformed glycerol, increasing specific rhamnolipid productivity to 25.8 mg/g cells-h and halving foam volume.
• Rhamnolipid composition varied, with soybean oil favoring monorhamnolipids (82%) and glycerol favoring dirhamnolipids (64%).
• Achieved a high rhamnolipid concentration of 42 g/l, with a yield of ~47% and volumetric productivity of 220 mg/l-h.

Conclusions:

• Optimized fermentation parameters and the use of soybean oil substantially improve rhamnolipid production efficiency.
• This study presents a viable strategy to overcome key limitations in microbial rhamnolipid manufacturing.
• The findings suggest a pathway towards more economical and scalable production of rhamnolipids for industrial applications.