Bromothymol blue and carbohydrate-sensitive plating media.
A new plating medium using bromothymol blue (BTB) indicator is described and compared with eosin-methylene blue (EMB), MacConkey, and Endo media. These media were tested with L-arabinose by plating fermenting and nonfermenting mutant strains of Escherichia coli. The minimum concentrations of L-arabinose that permitted differentiation of these strains were determined. Different concentrations were required for differentiating confluent patches of cells, isolated colonies, and closely spaced or adjacent colonies. L-Arabinose, L-rhamnose, D-lactose, and D-galactose were tested with modified enteric media and with BTB medium, again to determine minimum usable concentrations. BTB media and reformulated conventional media allowed detection of acidification, aerobically, at one-fifth to one-hundredth the (1%, wt/vol) concentration of carbohydrate used in standard indicator plates.
D000332:Aerobiosis; D001089:Arabinose / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D001979:Bromthymol Blue; D050260:Carbohydrate Metabolism; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D009154:Mutation; D010461:Peptones / Q000378:metabolism; D013237:Stereoisomerism; D013943:Thymol / Q000031:analogs & derivatives
D003470:Culture Media; D007202:Indicators and Reagents; D010461:Peptones; D013943:Thymol; D001089:Arabinose; D001979:Bromthymol Blue