Isolation and partial characterization of carotenoid underproducing and overproducing mutants from an extremely thermophilic Thermus thermophilus HB27 |
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| Affiliation: | 1. Institute of Food Research, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan;2. Zao Dairy Center, 251-4 Nanokahara, Togatta-onsen, Zao-machi, Katta, Miyagi 989-0916, Japan;3. Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan;4. Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan;5. Higuchi Matsunosuke Shoten, 1-14-2 Harimacho, Abeno-ku, Osaka 545-0022, Japan;1. College of Food and Biological Engineering, Jimei University, Xiamen 361021, China;2. Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen 361021, China;3. Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China;1. WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium;2. de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium;3. Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium;4. Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium;5. Department of Biochemistry and the Redox Biology Center, University of Nebraska, Lincoln, NE 68588, USA;6. Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-neuve, Belgium;7. Université Paris-Saclay, CNRS UPR 2301, Institut de Chimie des Substances Naturelles, 91198 Gif-sur-Yvette, France;8. European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany |
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| Abstract: | Twenty-two carotenoid underproducing and thirteen overproducing mutants were obtained from Thermus thermophilus HB27. The strain HB27 was found to produce at least seven colored carotenoids, believed to be identical to those produced by Thermus aquaticus YT1. Based on the results of the genetic analyses performed on twelve carotenoid underproducing mutants, they were classified into three groups; groups 1, 2 and 3. No colored carotenoid was extracted from the cells of mutants belonging to groups 2 and 3, although the accumulation of phytoene, a colorless carotenoid, was observed in group 2 strains. Group 1 was subdivided into groups 1-a and 1-b, where 1-a strains produced neither colored carotenoids nor phytoene and 1-b strains produced two polar colored carotenoids. All of the overproducing mutants produced about twelve times as much seven colored carotenoid mixtures as the parental strain. The mutation loci among all the overproducing mutants were very close to one another, possibly in the same gene. Carotenoid overproducing mutants showed an extensive resistancy to UV-irradiation and showed poorer growth at higher temperatures. Carotenoid underproducing mutants were slightly more UV-sensitive but they grew almost normally at higher temperatures. These results suggest that carotenoids are secondary metabolites which are not essential for growth of T. thermophilus. |
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