Fig. 1
Description and fermentation performance of the W105F strain in CWPR and CWP. a Design of a chromosomally integrated ethanol production pathway, indicating the candidate promoters and the integration loci. Straight arrows: coding sequences; curved arrows: promoters; half ovals: ribosome binding sites (RBSs); T symbol: transcriptional terminator; straight line: chromosomal DNA. The HA and HB regions represent the DNA sequences flanking the integration site that are used in homologous recombination, with the two selected loci in which integration occurred listed below. b MacConkey plate qualitatively showing the different color outputs of the indicated strains. For each strain, 2 μL of culture from long-term stock was pipetted on a non-selective MacConkey plate and incubated overnight at 37 °C. Control spots were prepared by using the W strain (DSM 1116), which has a wild-type mixed acid fermentation, and the TOP10 E. coli strain (Invitrogen), which is unable to consume lactose and no mixed acid fermentation is expected to occur. c, d Fermentation time course data from pH-controlled bioreactor experiments. Time series indicate the concentrations of sugars and ethanol with data points representing the average of two replicates and error bars the standard deviation. e Metabolic profiles from pH-controlled bioreactor experiments. Pie charts represent the distribution of residual sugars (Res sugars), fermentation products (EtOH, ethanol; Lac, lactic acid; Succ, succinic acid; Ac, acetic acid) and non-recovered carbon (Other). The c–e panels correspond to data of the plasmid-based ethanologenic WΔLFP-pL13 strain, used as a reference, in CWPR (c), the W105F strain in CWPR and CWP (d) and the metabolic profiles in these conditions (e). f Time series indicating the percentage of WΔLFP-pL13 or W105F bacterial population that maintained an ethanologenic phenotype over a month upon subculturing every 5 days