Improvement in citric acid production by haploidization of Aspergillus niger diploid strains |
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Affiliation: | 1. Department of Genetic Engineering, College of Life Science and Graduate School of Biotechnology, Kyung Hee University, Seochun-dong, Kiheung-ku, Yong In, 17104, South Korea;2. College of Medicine/East-West Medical Research Institute, Kyung Hee University, 1 Hoegi-dong, Dongdaemun-gu, Seoul, 02447, South Korea;1. Department of Botany, The Swedish Museum of Natural History, P.O. Box 50007, SE-104 05, Stockholm, Sweden;2. Department of Biology, Geology, Physic and Inorganic Chemical, Rey Juan Carlos University, Móstoles, 28932, Spain;1. Institute of Marine Science, University of Auckland, Auckland 1142, New Zealand;2. National Oceanography Centre, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK;3. Natural History Museum Vienna, Department of Geology and Palaeontology, Burgring 7, 1010 Vienna, Austria;1. Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, PR China;2. Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, Hainan, PR China |
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Abstract: | Segregation of diploid strains by a haploidizing agent was used to improve citric acid producing strains of Aspergillus niger. Stable diploid strains were obtained via protoplast fusion between two citric acid-producing strains from different genealogies, one for shaking culture and the other for solid culture. Diploid strains were treated by benomyl as a haploidizing agent, and many segregants were obtained. Prototrophic segregants were selected and their haploidy was confirmed by their conidial size and DNA contents. The prototrophic segregants were very variable in their citric acid productivities, some of them better either in shaking culture or in solid culture than both the parental strains. The presence of methanol stimulated citric acid production by the parental and the diploid strains. However, all prototrophic segregants derived from one diploid strain had higher productivities in solid cultures without methanol than in those with methanol. |
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