Mutants of the strain producing natamycin, Streptomyces gilvosporeus, were obtained after space-flight mutation. With respect to the sand spores and slant spores, the mutation ratios were up to 67.6% and 78.3% and the...Mutants of the strain producing natamycin, Streptomyces gilvosporeus, were obtained after space-flight mutation. With respect to the sand spores and slant spores, the mutation ratios were up to 67.6% and 78.3% and the survival ratio was 43.1% and 3.0%, respectively. An improved mutant producing natamycin, S. gilvosporeus LK-45, was screened, which showed natamycin productivity of 1420mg·L^-1. A mutant resistant to 2-deoxy glucose, S.gilvosporeus LK-119, was further obtained using a＇rational screening procedure. The natamycin productivity of 1940mg·L^-1 was achieved when glucose was used as the carbon source.展开更多
Ground cherry(Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold s...Ground cherry(Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold storage period. In order to maintain storage quality, a 1.5%(w/w) chitosan(CS) water solution containing 50 mg/L of natamycin(NA) was introduced. After all treatments were completed, the fruit was stored at 0°C and sampled every 10 d. At each sampling date, the following tests were performed: mold and yeast analyses; enzyme activity and content analyses which included superoxide dismutase(SOD), ascorbate peroxidase(APX), and malondialdehyde(MDA); and color analysis. In addition, a sensory evaluation was carried out for quality assessment at the end of the storage period. The results showed that the application of a chitosan coating combined with natamycin(CSNA) enhanced the activity of superoxide dismutase(SOD) and ascorbate peroxidase(APX), reduced the physiological rate of senescence, and inhibited pathogen attack. Thus, CSNA treatment can maintain ground cherries at an acceptable level of storage quality for 50 d.展开更多
文摘Mutants of the strain producing natamycin, Streptomyces gilvosporeus, were obtained after space-flight mutation. With respect to the sand spores and slant spores, the mutation ratios were up to 67.6% and 78.3% and the survival ratio was 43.1% and 3.0%, respectively. An improved mutant producing natamycin, S. gilvosporeus LK-45, was screened, which showed natamycin productivity of 1420mg·L^-1. A mutant resistant to 2-deoxy glucose, S.gilvosporeus LK-119, was further obtained using a＇rational screening procedure. The natamycin productivity of 1940mg·L^-1 was achieved when glucose was used as the carbon source.
基金supported by the National High-Tech R&D Program(863)of China(No.2012AA101703)
文摘Ground cherry(Physalis pubescens L.) is a kind of berry fruit favored by consumers in China; however, this fruit is particularly vulnerable to physiological senescence and pathogen attack during the traditional cold storage period. In order to maintain storage quality, a 1.5%(w/w) chitosan(CS) water solution containing 50 mg/L of natamycin(NA) was introduced. After all treatments were completed, the fruit was stored at 0°C and sampled every 10 d. At each sampling date, the following tests were performed: mold and yeast analyses; enzyme activity and content analyses which included superoxide dismutase(SOD), ascorbate peroxidase(APX), and malondialdehyde(MDA); and color analysis. In addition, a sensory evaluation was carried out for quality assessment at the end of the storage period. The results showed that the application of a chitosan coating combined with natamycin(CSNA) enhanced the activity of superoxide dismutase(SOD) and ascorbate peroxidase(APX), reduced the physiological rate of senescence, and inhibited pathogen attack. Thus, CSNA treatment can maintain ground cherries at an acceptable level of storage quality for 50 d.
