Bacterial Strains and Culture Conditions

R.capsulatus SB1003（Rif）24］was cultured on malate-minimal RCV medium［38］.Cells growing photosynthetically（designated PS cells）were anaerobically cultured at 30℃in completely filled screw-cap bottles（170 ml）at a light intensity of（30 W/m2）provided by a bank of lumiline lamps in an incubation chamber.The shift experiment from anaerobic（photosynthetic）to aerobic conditions was performed by abruptly shifting the PS cells to a 2-liter Erlenmeyer flask on a shaker and culturing those cells at the same light intensity and the same temperature with vigorous shaking（300 rpm）to achieve high aeration.In experiments determining the decay of specific mRNAs，cells were cultured photosynthetically to a density of 5×108 cells per ml（0.95 mg of protein per ml；8.5 μg of bacteriochlorophyll per mg of protein）.Transcription was then inhibited by the addition of proflavin（100 μg/ml）.Samples of 10 ml of cells were harvested just before adding the inhibitor to give a 0-min time point.After the cells were quickly mixed with proflavin and covered with a layer of sterile paraffin oil to exclude oxygen，the remaining cells were cultured under the same conditions and thereafter harvested by pipetting 10 ml each at various time intervals（5，10，20，or 40 min or 1，2，3，6，9，12，or 24 h）for RNA extraction.The crtA transposon mutant，KZR9A12，used for determining the crtA regulation has been previously described［43］.(https://www.daowen.com)