Marine Biotechnology

, Volume 11, Issue 2, pp 280–286 | Cite as

A Highly Thermosensitive and Permeable Mutant of the Marine Yeast Cryptococcus aureus G7a Potentially Useful for Single-Cell Protein Production and its Nutritive Components

  • Tong Zhang
  • Zhenming Chi
  • Jun Sheng
Original Article


The highly thermosensitive and permeable mutants are the mutants from which intracellular contents including proteins can be released when they are incubated both in the low osmolarity water and at the nonpermissive temperature (usually 37°C). After mutagenesis by using nitrosoguanidine, a highly thermosensitive and permeable mutant named Z114 was obtained from the marine yeast Cryptococcus aureus G7a. Of the total protein, 65.3% was released from the mutant cells suspended in distilled water after they were treated at 37°C overnight. However, only 12.3% of the total protein was released from the mutant cells suspended in 1.0 M sorbitol solution after they were treated at 37°C overnight. We found that intracellular density of the mutant treated at 37°C was greatly decreased, and cell volume of the mutant treated at 37°C was increased due to the increased protein release. However, no significant changes in the intracellular density and cell volume of the mutant were observed when its cells suspended in 1.0 M sorbitol solution were treated at 37°C. It was found that no big changes in cell growth, protein content, vitamin C content, nucleic acid content, fatty acids, and amino acid compositions of both the mutant and its wild type were detected. Therefore, the highly thermosensitive and permeable mutant still can be a good candidate as single-cell protein. This means that the method used in this study is a simple and efficient way to release protein from the highly thermosensitive and permeable yeast mutant cells with high protein content.


Thermosensitive and permeable mutant Single-cell protein Cryptococcus aureus G7a Marine yeasts Essential amino acids 



This research was supported by grants 2006AA09Z403 from Hi-Tech Research and Development Program of China (863).


  1. Alexandar I, Segundo PS, Venkov P, del Rey F, Vázquez de Aldana CR (2004) Characterization of a Saccharomyces cerevisiae thermosensitive lytic mutant leads to the identification of a new allele of the NUD1 gene. Intern J Biochem Cell Biol 36:2196–2213CrossRefGoogle Scholar
  2. Bradford MM (1976) A rapid and sensitive method for quantitation of microgra quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72:248–253PubMedCrossRefGoogle Scholar
  3. Brown MR, Barrett SM, Volkman JK, Nearhos SP, Nell JA (1996) Biochemical composition of new yeasts and bacteria evaluated as food for bivalve aquaculture. Aquaculture 143:341–360CrossRefGoogle Scholar
  4. Cabib E, Duran A (1975) Simple and sensitive procedure for screening yeast mutants that lyse at nonpermissive temperatures. J Bacteriol 124:1604–1606PubMedGoogle Scholar
  5. Chi ZM, Kohlwein SD, Paltauf F (1999) Role of phosphatidylinositol (PI) in ethanol production and ethanol tolerance by a high ethanol producing yeast. J Ind Microbiol Biotech 22:58–63CrossRefGoogle Scholar
  6. Chi ZM, Liu J, Zhang W (2001) Trehalose accumulation from soluble starch by Saccharomycopsis fibuligera sdu. Enzyme Microb Technol 28:240–245PubMedCrossRefGoogle Scholar
  7. Chi ZM, Liu ZQ, Gao LM, Gong F, Ma C, Wang XH, Li HF (2006) Marine yeasts and their applications in mariculture. J Ocean University China 5:251–256CrossRefGoogle Scholar
  8. Feng DX, Zhao BG (1997) Evaluation of protein quality of the new feeds by using essential amino acid index (EAAI). China Feed 7:10–13Google Scholar
  9. Gao LM, Chi ZM, Sheng J, Ni XM (2007) Single-cell protein production from Jerusalem artichoke extract by a recently isolated marine yeast Cryptococcus aureus G7a and its nutritive analysis. Appl Microbiol Biotechnol 77:825–832PubMedCrossRefGoogle Scholar
  10. Hancock RD, Galpin JR, Viola R (2000) Biosynthesis of L-ascorbic acid (vitamin C) by Saccharomyces cerevisiae. FEMS Microbiol Lett 186:245–250PubMedGoogle Scholar
  11. Kochert G (1978) Quantitation of the macromolecular components of microalgae. In: Hellebust JA, Craigie JS (eds) Handbook of physiological methods: physiological and biochemical methods. Cambridge University of Press, Cambridge, pp 190–195Google Scholar
  12. Patil RS, Ghormade V, Deshpande MV (2000) Chitinolytic enzymes: an exploration. Enzyme Microb Technol 26:473–483PubMedCrossRefGoogle Scholar
  13. Ratledge C (2004) Fatty acid biosynthesis in microorganisms being used for single cell oil production. Biochimie 86:807–815PubMedCrossRefGoogle Scholar
  14. Ravindra AP (2000) Value-added food: Single cell protein. Biotechnol Adv 18:459–479PubMedCrossRefGoogle Scholar
  15. Rhishipal R, Philip R (1998) Selection of marine yeasts for the generation of single cell protein from prawn-shell. Bioresour Technol 65:255–266CrossRefGoogle Scholar
  16. Sheng J, Chi ZM, Li J, Gao LM, Gong F (2007) Inulinase production by the marine yeast Cryptococcus aureus G7a and inulin hydrolysis by the crude inulinase. Proc Biochem 42:805–811CrossRefGoogle Scholar
  17. Strickland JDH, Parsons TR (1972) Kjehldahl method with ninhydrininish (low levels). In: Stevenson JC (ed) A practical handbook of seawater analysis. Bull: Fisheries Research Board of Canada, Ottawa, pp 227–236Google Scholar
  18. Ueda M, Tanaka A (2000) Genetic immobilization of proteins on the yeast cell surface. Biotechnol Adv 18:121–140PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.UNESCO Chinese Center of Marine BiotechnologyOcean University of ChinaQingdaoChina

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