The region for homologous recombination (590,459 to 593,751) was amplified from S. elongatus genomic DNA using the primers GR005 and GR006. Growth with glucose.We tested a possible means to complement the inability of S. elongatus to grow in the dark based on our hypothesis that efficient uptake of sugars is a missing factor for heterotrophy. No changes in cellular morphology, such as size and shape of the cells grown with or without glucose, were detected by microscopic observation (magnification, 1,000×). GFP assay on plate reader.All green fluorescent protein (GFP) assays were done using a Microtek Synergy H1 plate reader (BioTek). 4A). This was also the case with the galP-containing strain, while the growth of the wild type was not altered with the addition of any amount of IPTG up to 1 mM. Wild-type assays omitted spectinomycin. The Error bars represent standard deviations (in triplicate). 1B and C). strain PCC 6803, has been expressed from a plasmid-based expression system in Synechococcus elongatus strain PCC 7942 but could not be maintained, while genomic integration led to glucose sensitivity (4). Empty and filled symbols indicate growth without and with 5 g/liter xylose, respectively. Thus, we hypothesized that some downstream enzymes for converting xylose to central metabolites efficiently are missing. PCC 7002 (Ss7002), characterized by the production of trienoic alpha-linolenic acid (ALA, C18:3 Δ 9,12,15) by Δ9 … 2D). Only the eukaryotic gene for Glut1 was codon optimized for S. elongatus. All medium modifications are described below. It has been shown that the deletion of glgC in the wild type also impaired growth (27), although the effects of ΔglgC in this study were larger than those reported previously (27). The effects of bicarbonate on heterotrophic growth were characterized (Fig. Obligate phototrophs' core metabolism is very similar to that of heterotrophic counterparts exhibiting diverse trophic behavior. To characterize the expression of galP in S. elongatus, gfp was fused to the 3′ end of galP (denoted as galP-gfp). Research is investigating efficient harvesting of glucose from cellulose as a feedstock for biofuel production. 4A). Cyanobacteria, The precise causes for this inflexible trophic behavior are currently unknown; however, the matter is being studied (1, 2). It is an obligate photoautotroph, with a genome of approximately 2.7 Mb, and two endogenous plasmids, pANL and pANS. Synechococcus elongatus, Cyanobacteria/Melainabacteria group, It is also generally accepted that progenitors of cyanobacteria are the origin of plant plastids that have evolved through endosymbiosis. To clone the gentamicin resistance gene, pBBR1MCS-5 (21) was used as the PCR template with the primers IM573 and IM574. White and shaded areas indicate the light and dark cycles, respectively. Another possibility is exploring a light pulsing stratagem similar to the light-activated heterotrophic growth seen in Synechocystis sp. Herein, Synechococcus elongatus PCC 7942, a model cyanobacterium, was engineered to produce α-farnesene from CO 2. However, the maximum growth in the dark of the xylEAB strain (0.351 ± 0.014) was faster than that of the galP strain (0.269 ± 0.083) in the presence of their respective sugars (Fig. White and shaded areas indicate light and dark cycles, respectively. Spectinomycin was purchased from MP Biomedicals (Santa Ana, CA). ©2019 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493 SRI International is an independent, nonprofit corporation. 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