title: Improved tolerance of recombinant Escherichia coli to the toxicity of crude glycerol by overexpressing trehalose biosynthetic genes (otsBA) for the production of β-carotene.
abstract: This study aims to investigate whether overexpressing the trehalose biosynthetic gene, otsBA operon, in β-carotene-producing recombinant Escherichia coli protects cells from toxic impurities in crude glycerol. The concentrations of potassium and methanol in crude glycerol were too low to inhibit cell growth. Cell growth and production in control cell culture were inhibited significantly in the presence of a small amount of crude fatty acids. Peroxides were generated in the presence of crude fatty acids during autoclaving and, thus, the inhibitory effect of crude fatty acids was caused primarily by these peroxides. Engineered cells overexpressing otsBA tolerated crude fatty acids (≤42 wet-g/L), methanol (≤7.5 g/L), and t-BuOOH (≤60 μM) in separate experiments and tolerated up to 60 g/L crude glycerol. These results demonstrate that overexpressing otsBA endowed cells with the capacity to tolerate the toxicity of crude glycerol for direct use.
authors.affiliation: Department of Chemical & Biological Engineering and ERI, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Anh Do Quynh
authors.initials: Ado Q
authors.lastname: Nguyen
authors.forename: You Geun
authors.initials: YG
authors.lastname: Kim
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Kim
authors.forename: Chang-Joon
authors.initials: CJ
authors.lastname: Kim
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005964:Glucosyltransferases / Q000235:genetics*; D005990:Glycerol / Q000633:toxicity*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D010957:Plasmids; D011995:Recombination, Genetic; D014199:Trehalose / Q000096:biosynthesis*; D019207:beta Carotene / Q000096:biosynthesis*
chemical_list: D029968:Escherichia coli Proteins; D019207:beta Carotene; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; C518654:OtsB protein, E coli; D010744:Phosphoric Monoester Hydrolases; D005990:Glycerol
keywords: Crude glycerol; Recombinant Escherichia coli; Tolerance; Trehalose biosynthetic operon; β-Carotene