Abstract: A chromogenic .beta.-galactosidase substrate producing an insoluble precipitate of a first color when reacted upon by .beta.-galactosidase and a chromogenic .beta.-glucuronidase substrate producing an insoluble precipitate of a second, contrasting color when reacted upon by .beta.-glucuronidase are combined in test medium for quantitatively identifying and differentiating general coliforms and E. coli. The .beta.-galactosidase substrate 5-bromo-4-chloro-3-indolyl-.beta.-D-galactopyranoside which produces an indigo blue precipitate when reacted upon by .beta.-galactosidase may be used with one of the novel compounds 6-chloroindolyl-.beta.-D-glucuronide, 4,6-dichloroindolyl-.beta.-D-glucuronide, 6,7-dichloroindolyl-.beta.-D-glucuronide, and 4,6,7-trichloroindolyl-.beta.-D-glucuronide, which produce mauve or magenta precipitates when reacted upon by .beta.-glucuronidase. The .beta.-glucuronidase substrate 5-bromo-4-chloro-3-indolyl-.beta.

Abstract: Novel amino-hydroxy-alkylene sulfonic acid zwitterions are described which have the general formulas ##STR1## wherein A and B are each independently a hydrogen atom, an aliphatic, cycloaliphatic or hydroxyaliphatic group,n is one or two, andR.dbd.N is a cyclic radical comprising one or two ring nitrogen atoms, zero or one ring oxygen atoms and the remainder of the ring being carbon atoms, and water soluble salts of said acids. These organo-sulfonic acid compounds are useful as hydrogen ion buffers in biological research and particularly for tissue culture.