title: Multiple rRNA operons are essential for efficient cell growth and sporulation as well as outgrowth in Bacillus subtilis.
abstract: The number of copies of rRNA (rrn) operons in a bacterial genome differs greatly among bacterial species. Here we examined the phenotypic effects of variations in the number of copies of rRNA genes in the genome of Bacillus subtilis by analysis of eight mutant strains constructed to carry from two to nine copies of the rrn operon. We found that a decrease in the number of copies from ten to one increased the doubling time, and decreased the sporulation frequency and motility. The maximum levels for transformation activity were similar among the strains, although the competence development was significantly delayed in the strain with a single rrn operon. Normal sporulation only occurred if more than four copies of the rrn operon were present, although ten copies were needed for vegetative growth after germination of the spores. This behaviour was seen even though the intracellular level of ribosomes was similar among strains with four to ten copies of the rrn operon. Furthermore, ten copies of the rrn operon were needed for the highest swarming activity. We also constructed 21 strains that carried all possible combinations of two copies of the rrn operons, and found that these showed a range of growth rates and sporulation frequencies that all fell between those recorded for strains with one or three copies of the rrn operon. The results suggested that the copy number of the rrn operon has a major influence on cellular processes such as growth rate and sporulation frequency.
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Koichi
authors: K
authors: Yano
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Tetsuya
authors: T
authors: Wada
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Shota
authors: S
authors: Suzuki
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Kazumi
authors: K
authors: Tagami
authors: Genome Research Center, Nodai Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan.
authors: Takashi
authors: T
authors: Matsumoto
authors: Genome Research Center, Nodai Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan.
authors: Yuh
authors: Y
authors: Shiwa
authors: Genome Research Center, Nodai Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan.
authors: Taichiro
authors: T
authors: Ishige
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Yasuhiro
authors: Y
authors: Kawaguchi
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Kenta
authors: K
authors: Masuda
authors: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551, Japan.
authors: Genki
authors: G
authors: Akanuma
authors: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Hideaki
authors: H
authors: Nanamiya
authors: Department of Genetics, Graduate University for Advanced Studies, Sokendai, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.|Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.
authors: Hironori
authors: H
authors: Niki
authors: Department of Bioscience, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan.|Genome Research Center, Nodai Research Institute, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan.
authors: Hirofumi
authors: H
authors: Yoshikawa
authors: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku Nishi-ikebukuro 3-34-1, Tokyo 171-8501, Japan.
authors: Fujio
authors: F
authors: Kawamura
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D002455:Cell Division; D061269:DNA Transformation Competence; D018628:Gene Dosage; D020043:Genes, Essential; D008124:Locomotion; D009154:Mutation; D013171:Spores, Bacterial / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D014169:Transformation, Bacterial; D012407:rRNA Operon