Abstract
Microalgae are recognized as a third generation feedstock for biofuel production due to their rapid growth rates and lignin-free characteristics. In this study, a lipid extracted microalgal biomass residues was used as the raw material to produce isoprene, α-pinene and β-pinene with an engineered E. coli strain. We adopted an optimal sulfuric acid hydrolysis method (1:7 ratio of solid to acid solution, 32% (w/v) concentration of sulfuric acid solution at 90 °C for 90 min) to efficiently convert holocellulose into glucose efficiently (6.37 g/L). Futhermore, we explored a novel detoxification strategy (phosphoric acid/calcium hydroxide) to remove inhibitors and notably acetic acid, furfural and 5-hydroxymethylfurfural (5-HMF) were reduced by 5.32%, different number given later 99.19% and 98.22%, respectively. Finally, the fermentation concentrations of isoprene (223.23 mg/L), α-pinene (382.21 μg/L) and β-pinene (17.4 mg/L) were achieved using the detoxified hydrolysate as the carbon source, equivalent to approximately 86.02%, 90.16% and 88.32% of those produced by the engineered E. coli strain fermented on pure glucose, respectively.
Highlights
As the simplest member of isoprenoids, isoprene is an important platform chemical which could be used for producing medicines, pesticides, fragrances, and especially synthetic rubber [1,2,3].Its derivatives, α-pinene and β-pinene, have the potential to be used for aviation fuel production owing to their compact structures and reactive olefin functionality properties [4,5].Currently, because of the structural complexity of isoprenoids, the reduced availability of fossil resources, and the rapid growth of microorganisms, there is potential for isoprenoids production using biosynthetic methods to replace chemical synthesis [4,5]
These results revealed that the carbon sources, including pure glucose, raw hydrolysate, and hydrolysates detoxified by methods
lipid extracted microalgal biomass residues (LMBRs) are a potential raw material for biofuel production due to their absence of lignin and the presence of fermentable sugar in the microalgal residual biomass. 6.37 g/L glucose was achieved after hydrolyzing the lipid extracted microalgae with 1:7 ratio of solid to acid solution, 32% (w/v) concentration of sulfuric acid at 90 ◦ C for 90 min
Summary
As the simplest member of isoprenoids, isoprene is an important platform chemical which could be used for producing medicines, pesticides, fragrances, and especially synthetic rubber [1,2,3].Its derivatives, α-pinene and β-pinene, have the potential to be used for aviation fuel production owing to their compact structures and reactive olefin functionality properties [4,5].Currently, because of the structural complexity of isoprenoids, the reduced availability of fossil resources, and the rapid growth of microorganisms, there is potential for isoprenoids production using biosynthetic methods to replace chemical synthesis [4,5]. As the simplest member of isoprenoids, isoprene is an important platform chemical which could be used for producing medicines, pesticides, fragrances, and especially synthetic rubber [1,2,3]. Α-pinene and β-pinene, have the potential to be used for aviation fuel production owing to their compact structures and reactive olefin functionality properties [4,5]. Because of the structural complexity of isoprenoids, the reduced availability of fossil resources, and the rapid growth of microorganisms, there is potential for isoprenoids production using biosynthetic methods to replace chemical synthesis [4,5]. A heterologous MVA pathway was used to produce isoprene, α-pinene and β-pinene with suitably engineered E. coli strains (YJM25, YJM29, FHR-2, respectively). Due to the bottleneck of feedstock availability, biotechnology need to be applied to isoprenoids production by using more economical resources
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