Combinatorial pretreatment and fermentation optimization enabled a record yield on lignin bioconversion.

Area of Science:

• Biotechnology
• Biorefining
• Microbial lipid production

Background:

• Lignin valorization is crucial for sustainable biorefineries, offering a feedstock for value-added products.
• Oleaginous bacteria like Rhodococcus opacus can convert aromatic substrates into lipids for biofuels.
• Challenges include low lignin reactivity and underdeveloped fermentation hindering efficient bioconversion.

Purpose of the Study:

• To improve lignin valorization into lipids using Rhodococcus opacus PD630.
• To evaluate combinatorial pretreatment and optimized fermentation strategies.
• To enhance the production of microbial lipids from lignin.

Main Methods:

• Combinatorial pretreatment of lignin was employed.
• Detoxification strategies (e.g., heating) were applied to the lignin stream.
• Fermentation optimization, including fed-batch strategies and laccase treatment, was performed.
• Scale-up studies were conducted in a 2.0-l fermenter.

Main Results:

• Combinatorial pretreatment yielded 12.8-75.6% higher lipid concentrations compared to single pretreatment.
• Detoxification, particularly heating, further increased lipid concentration by 2.9-9.7%.
• Fed-batch fermentation with laccase treatment achieved a cell dry weight of 10.1 g/l and lipid concentration of 1.83 g/l.

Conclusions:

• Combinatorial pretreatment and fermentation optimization effectively enhance lipid production from lignin.
• This integrated strategy facilitates lignin bioconversion into lipids, promoting biorefinery applications.
• The study demonstrates a viable pathway for lignin valorization into biofuels.