Figure 1
Listing of cultivation conditions applied in (upper part), and presentation and comparative characterization of specific productivities determined (lower part) for fermentations of the present study; single fermentations runs, except for where indicated a-c (three biological replicas). SMM-TE, trace elements solution of medium SMM [26]; PEG, polyethylene glycol 6000; TES, N-Tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid; TMS1, trace mineral solution 1; const. agit. or min. DO, cultivation performed at given constant agitation from the start/culture started at min. agitation (~325 rpm) or agitation was adjusted automatically to maintain at least the given percentage of dissolved oxygen (DO); 900/1100/1300 (ferm. #16a-c) indicates manual change of constant agitation from 900 to 1100 to 1300 rpm after 21 and 26 h, respectively, in each of three biological replicas to prevent a DO of lower than approx. 50%, returned to 900 rpm after 45 h. Ferm. #18a-c and #19a-c were experiments with massive volume reduction due to high resolution time-series sampling. Ferm. #21, L-glutamate amount exchanged with ammonium sulfate of the respective molar amount of nitrogen; ferm. #24/25, use of custom-made 350 mL fermentation vessels with 200 mL working volume; ferm. #25, use of 20 g/L fully 13 C-labelled D-glucose (*). All fermentations were performed at 30°C and pH 7.0, automatically adjusted with 2 M HCl and 2 M NaOH. Initial specific productivity qPinit of secondary metabolites determined by measuring the pigment levels in culture samples using the RED/TBP assays and plotting the data as a function of time, linear regression of the initial production data points after production start (usually within the first 15 h after sec. metabolites have first been detected); max CDW, maximum biomass concentration (cell dry weight). X symbols indicate the maximum biomass concentration, red and blue bars the initial specific productivity of RED and TBP, respectively. Bold font indicates changes in cultivation conditions in the order of presentation from ferm. #1 to ferm. #25.