Comparative study of the bioconversion process using R-(+)- and S-(-)-limonene as substrates for Fusarium oxysporum...

Area of Science:

• Biotechnology
• Microbial Biotransformation
• Enzyme Catalysis

Background:

• Fusarium oxysporum 152B is a known biocatalyst for R-(+)-limonene to α-terpineol conversion.
• Limonene bioconversion pathways are crucial in producing valuable chemical compounds.

Purpose of the Study:

• To compare the bioconversion of S-(-)-limonene to limonene-1,2-diol with the established R-(+)-limonene to α-terpineol pathway.
• To characterize the optimal conditions for S-(-)-limonene bioconversion using Fusarium oxysporum 152B.

Main Methods:

• Utilized Fusarium oxysporum 152B as the biocatalyst for both R-(+)- and S-(-)-limonene.
• Tested S-(-)-limonene bioconversion under cell permeabilization, anaerobic conditions, and biphasic systems.
• Employed ultra-structural analysis for cellular detoxification characterization.

Main Results:

• Biocatalyst showed resistance to permeabilization but lost viability and activity without limonene-1,2-diol production.
• S-(-)-limonene bioconversion is an aerobic process catalyzed by intracellular limonene-1,2-epoxide hydrolase.
• The process is cofactor-dependent, as no product was detected under anaerobic conditions.

Conclusions:

• S-(-)-limonene bioconversion to limonene-1,2-diol requires specific aerobic, intracellular, and cofactor-dependent enzymatic activity.
• Cellular integrity and viability are critical for biocatalyst function in limonene biotransformation.
• This study provides the first characterization of S-(-)-limonene bioconversion using cellular detoxification and ultra-structural analysis.