Pectin lyase overproduction by Penicillium griseoroseum mutants resistant to catabolite repression

Abstract Expression of pectinolytic genes is regulated by catabolic repression limiting the production of pectin lyase (PL) if the natural inducer, pectin, is missing from the growth medium. Here, we report the isolation of Penicillium griseoroseum mutants resistant to 2-deoxy-d-glucose (DG) that show resistance to catabolite repression and overproduce PL. Three spontaneous and nine UV-induced mutants were obtained. Some mutants produced sectors (segments morphologically different) that were also studied. The mutants were analyzed for pectinases production on pectinase-agar plates and five mutants and two sectors showing larger clearing zones than the wild type were selected for quantitative assay. Although PL production higher than the wild type has been found, phenotype instability was observed for most of the mutants and, after transfers to nonselective medium, the DG resistance was no longer present. Only mutants M03 and M04 were stable maintaining the DG-resistance phenotype. When growing for 120 h in liquid medium containing glucose with or without pectin, both mutants showed higher PL production. In the presence of glucose as sole carbon source, the mutant M03 produced 7.8-fold more PL than the wild type. Due its phenotypic stability and PL overproduction, the mutant M03 presents potential for industrial applications.

Preparation of catalitaxol-deficient defective strains by using ultraviolet mutagenesis / 生物工程学报

Secondary metabolites of endophytic fungi FSN002 from Juglans mandshurica Maxim have excellent liver cancer resistance. Preparation of mutant strains is an important means to study the biosynthesis mechanism of catalitaxol. Fungal spores germinating young hyphae with 4 to 6 cells after culturing for 13 hours were used as starting materials of ultraviolet (UV) mutagenesis. UV light intensity and irradiation time have a linear relationship with fungal mortality. The two factors had no obvious interactions. When UV light was 90 000 μJ/cm2 and irradiation time for 6 s, the mortality of fungi was around 95%. Under the optimization mutation condition, two mutant strains were obtained, of which one lost the synthesis ability of catalitaxol completely, and the another synthetized only 16% catalitaxol of the wild strain. Our findings may serve basis for further study on the biosynthesis mechanism and efficient production of catalitaxol.

Screening and mutation of a marine Bacillus megaterium to resolute 3-chloro-1, 2-epoxypropane / 中国药学杂志

OBJECTIVE: To obtain and mutate a marine Bacillus megaterium to resolute pharmaceutical intermediate, 3-chloro-1,2-epoxypropane. METHODS: From marine sediment, a 3-chloro-1,2-epoxypropane-resolute strain was isolated and mutated by ultraviolet rays and N+ ion. RESULTS: The strain was identified as Bacillus megaterium on the basis of biophysical and biochemical test. The optimum salinity for growth was 2%, and the result of optimum salinity showed that the microbe was a typical marine microorganism. A positive mutant exhibited excellent resolution with ee value of 99% and yield of 42%. CONCLUSION: The marine bacillus megaterium shows a large potential for industrial production.

The Molecular Genetics Of Skin Diseases.

There are many aspects to the molecular genetics of skin diseases. This paper is comprehensive in that it deals with structural components of the skin and the disease which can result from defect in these components. It also deals with pigmentation, ultraviolet mutagenesis, and tumors of the skin, immunology and autoimmunity and some virus disease of the skin. All of these subjects are necessarily dealt with superficially: in each case there is an introduction to the literature of the 1990s for further reading. Key references to older literature are also included.