Hydrocarbon emulsification by Candida tropicalis and Debaryomyces polymorphus

Area of Science:

• Microbiology
• Biotechnology
• Environmental Science

Background:

• Biosurfactants are surface-active compounds with diverse applications.
• Microbial production of biosurfactants is an area of significant research interest.
• Utilizing waste materials for microbial cultivation is crucial for sustainable processes.

Purpose of the Study:

• To investigate the potential of Candida tropicalis and Debaryomyces polymorphus to produce bioemulsifiers/biosurfactants.
• To evaluate the emulsification activity of these microorganisms on hexadecane and oily waste.
• To characterize the properties of the produced bioemulsifying compounds.

Main Methods:

• Shake cultivation of C. tropicalis and D. polymorphus using hexadecane and oily waste as substrates.
• Measurement of emulsification activity, specifically towards aromatic hydrocarbons.
• Stability testing of the culture broth's emulsification activity under varying pH, NaCl concentrations, and temperatures.
• Characterization of the isolated bioemulsifying factor's composition (lipid, protein, carbohydrate).

Main Results:

• C. tropicalis exhibited superior emulsification activity compared to D. polymorphus, with notable specificity for aromatic hydrocarbons.
• The emulsification activity of C. tropicalis culture broth demonstrated good stability across a range of pH and NaCl concentrations (up to 5%).
• Activity was marginally affected by heat but significantly inhibited (90%) by 0.3% CaCl2. The isolated factor comprised 40% lipid, 22% protein, and 17.5% carbohydrate.

Conclusions:

• Candida tropicalis is a promising candidate for biosurfactant production, especially for aromatic hydrocarbon remediation.
• The bioemulsifier produced by C. tropicalis possesses favorable stability characteristics.
• Further research into the isolated bioemulsifying factor could lead to novel biotechnological applications.