Butanol fermentation from microalgae-derived carbohydrates after ionic liquid extraction.

Area of Science:

• Biotechnology and Biofuels
• Renewable Energy Sources
• Algal Biomass Utilization

Background:

• Lipid extracted algae (LEA) is a non-food crop rich in fermentable carbohydrates, making it a promising feedstock for alcohol fuel production.
• Current research focuses on lignocellulosic materials, but LEA presents an alternative with readily available starch.
• Efficiently converting algal biomass into biofuels is crucial for sustainable energy solutions.

Purpose of the Study:

• To compare the efficacy of ionic liquid extracted algae (ILEA) and hexane extracted algae (HEA) for acetone, butanol, and ethanol (ABE) fermentation.
• To evaluate the impact of acid hydrolysis and detoxification on ABE fermentation yields from LEA.
• To assess the feasibility of co-producing biodiesel and butanol from a single algal feedstock.

Main Methods:

• Extraction of lipids from algae using ionic liquid (ILEA) and hexane (HEA) methods.
• Acid hydrolysis of extracted algal biomass to produce fermentable sugars.
• Acetone, butanol, and ethanol (ABE) fermentation of algal hydrolysates and direct starch fermentation.
• Detoxification of hydrolysates when necessary to support microbial fermentation.

Main Results:

• The highest butanol titer (8.05 g L(-1)) was achieved using acid hydrolysates of HEA, though detoxification was required.
• ILEA hydrolysates supported product formation without detoxification.
• Direct fermentation of ILEA and HEA starches yielded 4.99 g L(-1) and 6.63 g L(-1) butanol, respectively, simplifying the process.
• The study confirmed the compatibility of producing both biodiesel and butanol from the same algal feedstock.

Conclusions:

• Both ILEA and HEA are suitable feedstocks for ABE fermentation, with HEA yielding higher butanol titers after acid hydrolysis and detoxification.
• Direct fermentation of algal starch offers a simplified and effective route to butanol production.
• Co-production of biodiesel and butanol from algae can reduce feedstock costs and enhance process economics.