title: Boosting D-lactate production in engineered cyanobacteria using sterilized anaerobic digestion effluents.
abstract: Anaerobic digestion (AD) is an environmentally friendly approach to waste treatment, which can generate N and P-rich effluents that can be used as nutrient sources for microalgal cultivations. Modifications of AD processes to inhibit methanogenesis leads to the accumulation of acetic acid, a carbon source that can promote microalgal biosynthesis. This study tested different AD effluents from municipal wastes on their effect on D-lactate production by an engineered Synechocystis sp. PCC 6803 (carrying a novel lactate dehydrogenase). The results indicate that: (1) AD effluents can be supplemented into the modified BG-11 culture medium (up to 1:4 volume ratio) to reduce N and P cost; (2) acetate-rich AD effluents enhance D-lactate synthesis by ∼ 40% (1.2g/L of D-lactate in 20 days); and (3) neutral or acidic medium had a deleterious effect on lactate secretion and biomass growth by the engineered strain. This study demonstrates the advantages and guidelines in employing wastewater for photomixotrophic biosynthesis using engineered microalgae.
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA.
authors.forename: Whitney D
authors.initials: WD
authors.lastname: Hollinshead
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA; Biological and Materials Science Center, Sandia National Laboratories, Livermore, CA 94550, USA.
authors.forename: Arul M
authors.initials: AM
authors.lastname: Varman
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA.
authors.forename: Le
authors.initials: L
authors.lastname: You
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Hembree
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO 63130, USA. Electronic address: yinjie.tang@seas.wustl.edu.
authors.forename: Yinjie J
authors.initials: YJ
authors.lastname: Tang
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000693:Anaerobiosis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000096:biosynthesis*; D060847:Metabolic Engineering / Q000379:methods*; D012037:Refuse Disposal; D012722:Sewage / Q000382:microbiology; D013242:Sterilization; D046939:Synechocystis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology
chemical_list: D000085:Acetates; D019344:Lactic Acid; D012722:Sewage; D062065:Wastewater
keywords: Municipal waste; Photomixotrophic; Synechocystis 6803; d-lactate dehydrogenase