Applied Microbiology and Biotechnology

, Volume 102, Issue 10, pp 4467–4475 | Cite as

The effects of gene disruption of Kre6-like proteins on the phenotype of β-glucan-producing Aureobasidium pullulans

  • Hirofumi Uchiyama
  • Atsushi Iwai
  • Hideo Dohra
  • Toshiyuki Ohnishi
  • Tatsuya Kato
  • Enoch Y. Park
Biotechnologically relevant enzymes and proteins


Killer toxin resistant 6 (Kre6) and its paralog, suppressor of Kre null 1 (Skn1), are thought to be involved in the biosynthesis of cell wall β-(1 → 6)-D-glucan in baker’s yeast, Saccharomyces cerevisiae. The Δkre6Δskn1 mutant of S. cerevisiae and other fungi shows severe growth defects due to the failure to synthesize normal cell walls. In this study, two homologs of Kre6, namely, K6LP1 (Kre6-like protein 1) and K6LP2 (Kre6-like protein 2), were identified in Aureobasidium pullulans M-2 by draft genome analysis. The Δk6lp1, Δk6lp2, and Δk6lp1Δk6lp2 mutants were generated in order to confirm the functions of the Kre6-like proteins in A. pullulans M-2. The cell morphologies of Δk6lp1 and Δk6lp1Δk6lp2 appeared to be different from those of wild type and Δk6lp2 in both their yeast and hyphal forms. The productivity of the extracellular polysaccharides, mainly composed of β-(1 → 3),(1 → 6)-D-glucan (β-glucan), of the mutants was 5.1–17.3% less than that of wild type, and the degree of branching in the extracellular β-glucan of mutants was 14.5–16.8% lower than that of wild type. This study showed that the gene disruption of Kre6-like proteins affected the cell morphology, the productivity of extracellular polysaccharides, and the structure of extracellular β-glucan, but it did not have a definite effect on the cell viability even in Δk6lp1Δk6lp2, unlike in the Δkre6Δskn1 of S. cerevisiae.


Aureobasidium pullulans β-glucan Polysaccharides Killer toxin resistant 6 Mutant 


Author contributions

Conceived and designed the experiments: H.U., T.K., and E.Y.P. Performed the experiments: H.U. Analyzed the data: H.U. and A.I. Contributed reagents/materials/analysis tools: H.D., T.O., T.K., and E.Y.P. Wrote the paper: H.U. and A.I.

Compliance with ethical standards

Conflict of interest

There are potential competing interests to declare. Hirofumi Uchiyama and Atsushi Iwai are employees of Aureo-Science Co., Ltd. The β-(1 → 3),(1 → 6)-D-glucan-containing A. pullulans-culture broth and its derivatives are marketed by Aureo Co., Ltd., and by Aureo-Science Co., Ltd. There are no other patents, products in development, or marketed products to declare.

Supplementary material

253_2018_8947_MOESM1_ESM.pdf (262 kb)
ESM 1 (PDF 261 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Laboratory of Biotechnology, Integrated Bioscience Section, Graduate School of Science and TechnologyShizuoka UniversityShizuokaJapan
  2. 2.Aureo-Science Co., Ltd.SapporoJapan
  3. 3.Instrumental Research Support Office, Research Institute of Green Science and TechnologyShizuoka UniversityShizuokaJapan
  4. 4.Laboratory of Organic Chemistry of Natural Products, Green Chemistry Research Division, Research Institute of Green Science and TechnologyShizuoka UniversityShizuokaJapan
  5. 5.Laboratory of Biotechnology, Green Chemistry Research Division, Research Institute of Green Science and TechnologyShizuoka UniversityShizuokaJapan

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