Optimization, characterization and biosafety of carotenoids produced from whey using Micrococcus luteus

Area of Science:

• Microbiology
• Biotechnology
• Natural Products Chemistry

Background:

• Micrococcus luteus produces valuable carotenoid pigments.
• Optimization of culture conditions is crucial for enhancing pigment yield and characterizing bioactivity.
• Understanding the antimicrobial, antioxidant, and cytotoxic properties is essential for potential applications.

Purpose of the Study:

• To optimize the production of carotenoid pigments from Micrococcus luteus (ATCC 9341) using statistical media screening.
• To characterize the antimicrobial, antioxidant, cytogenetic, and cytotoxic activities of the produced carotenoids.
• To evaluate the biosafety and potential applications of M. luteus carotenoids.

Main Methods:

• A Box-Behnken design was employed to optimize media components (whey concentration, inoculum size, pH, temperature, agitation speed).
• High-performance liquid chromatography (HPLC) was used for carotenoid identification.
• Antimicrobial activity was assessed via inhibition zone diameters (IZD).
• Antioxidant activity was determined using the DPPH assay (IC50).
• Cytotoxicity was evaluated against normal mouse liver cells, and cytogenetic effects were analyzed.

Main Results:

• Optimized conditions yielded 2.19 g/L of carotenoids, with a productivity of 0.045 g L-1 h-1.
• HPLC analysis identified 12 distinct carotenoid compounds.
• Extracts showed moderate antimicrobial efficacy against Gram-positive bacteria (e.g., Bacillus cereus, Staphylococcus aureus, E. faecalis) but limited activity against Gram-negative bacteria.
• Antioxidant activity (IC50) was 152.80 mg/100mL.
• Cytotoxicity was low (IC50 > 300 μg/mL) with no significant genotoxic effects observed.

Conclusions:

• Statistical optimization significantly enhanced carotenoid production from M. luteus.
• M. luteus carotenoids exhibit promising moderate antimicrobial and antioxidant properties.
• The characterized low cytotoxicity and biosafety profile support the potential application of these carotenoids.