title: Chitinase-overproducing mutant of Serratia marcescens.
abstract: Genetic modification of Serratia marcescens QMB1466 was undertaken to isolated mutants which produce increased levels of chitinolytic activity. After mutagenesis with ultraviolet light, ethyl methane sulfonate or N-methyl-N'-nitro-N-nitrosoguanidine, 19,940 colonies were screened for production of enlarged zones of clearing (indicative of chitinase activity) on chitin-containing agar plates. Forty-four chitinase high producers were tested further in shake flask cultures. Mutant IMR-1E1 was isolated which, depending on medium composition, produced two to three times more than the wild type of the other components of the chitinolytic enzyme system--a factor involved in the hydrolysis of crystalline chitin and chitobiase. After induction by chitin, endochitinase and chitobiase activity appeared at similar times for both IMR-1E1 and QMB1466, suggesting possible coordinate control of these enzymes. The results are consistent with IMR-1E1 containing a regulatory mutation which increased production of the components of the chitinolytic enzyme system and/or with IMR-1E1 containing a tandem duplication of the chitinase genes. The high rate of reversion of IMR-1E1 to decreased levels of chitinase production suggests that the overproduction of chitinase by IMR-1E1 is due to a tandem gene duplication.
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D002686:Chitin; D002688:Chitinases / Q000096:biosynthesis* / Q000235:genetics; D004790:Enzyme Induction; D009154:Mutation; D012706:Serratia marcescens / Q000201:enzymology* / Q000235:genetics
chemical_list: D002686:Chitin; D002688:Chitinases; D000118:Acetylglucosaminidase