title: High-level production of  -galactosidase by Escherichia coli merodiploids.
abstract: Two merodiploids of Escherichia coli that contain genes for the lac operon on both chromosome and episome were tested for production of lac enzymes after growth on various carbon sources. The specific activity of beta-galactosidase (and of thiogalactoside transacetylase) was about twice that from haploid cells when grown on glycerol. With succinate as carbon source, the specific activity increased by an additional factor of 3. Up to 25% of the soluble cell protein is beta-galactosidase in these strains, one of which is inducible and the other constitutive. The enzyme is purified easily in high yield by ammonium sulfate fractionation and electrophoresis.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000645:Ammonium Sulfate; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D001431:Bacteriological Techniques; D002474:Cell-Free System; D011232:Chemical Precipitation; D002845:Chromatography; D002951:Citrates / Q000378:metabolism; D003470:Culture Media; D004171:Diploidy; D004586:Electrophoresis; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development; D005690:Galactose; D005696:Galactosidases / Q000096:biosynthesis* / Q000302:isolation & purification; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006027:Glycosides; D006238:Haploidy; D007785:Lactose / Q000378:metabolism; D013386:Succinates / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D003470:Culture Media; D006027:Glycosides; D013386:Succinates; D000123:Acetyltransferases; D005696:Galactosidases; D005947:Glucose; D007785:Lactose; D005990:Glycerol; D000645:Ammonium Sulfate; D005690:Galactose