Advantages
Eliminates overestimation of budding yeast colonies (over 100%):
- Quantifies physical cell separation to correct conventional, inaccurate viability assessments.
A simple protocol that can be implemented using existing equipment:
- Requires only the addition of microscopic observation using tools such as a hemocytometer; no expensive new equipment is needed.
Enhancing quality control for industrial yeast:
- Enables extremely accurate assessment of the viability of baker’s yeast and brewer’s yeast, contributing to improved fermentation yield and stable quality.
Background & Technology
When evaluating the stress tolerance and vitality of budding yeast, it is essential to calculate colony-forming ability, which indicates the microorganism’s capacity for survival and proliferation. Traditionally, this ability has been calculated as a ratio, with the total number of cells in suspension—measured by methods such as flow cytometry—serving as the numerator and the number of colonies on the culture medium as the denominator. However, since budding yeast proliferates in a chain of single cells (mother and daughter cells), even though each cell in suspension is counted as a “single cell” (an aggregate of single cells), the physical pressure applied when spreading the culture onto a plate with a spreader causes the cells to separate (disperse). In such cases, the separated yeast cells each form independent colonies, resulting in a contradiction where the calculated colony-forming ability significantly exceeds 100%.
This technology involves measuring the average number of elementary cells by microscopically observing budding yeast before and after spreading using a hemocytometer or similar device, and then calculating a “separation coefficient” from this data. By correcting the conventional calculation formula using this separation coefficient, it is possible to eliminate the influence of cell separation caused by the physical pressure during spreading and to evaluate the true colony-forming ability of budding yeast with extreme accuracy.
Data
Budding yeast was subjected to salt stress, and its survival rate was calculated using both conventional methods and the method described in this study. The results showed that while the colony-forming ability measured by the conventional method ranged from 190% to 240%, the value obtained using the correction method described in this study ranged from 86% to 110%, confirming that it closely matched the actual survival rate (approximately 99%; cell integrity).
Expectations
Fukuoka University is seeking companies interested in this technology. Specifically, the following types of collaboration and partnerships are desired. It is possible to disclose unpublished data through the execution of a CDA with the university, as well as to arrange direct meetings with the PI. Please feel free to contact us.
Yeast-related companies (bread yeast manufacturers, breweries and wineries, bioethanol industry):
- Joint research, including pilot-scale demonstration experiments using your company’s actual samples, and the development of specialized software for budding yeast in collaboration with AI-based automated analysis software providers.
Manufacturers of testing equipment and reagents:
- Next-generation software for automatic colony counters incorporating this computational algorithm; “research reagent kits for measuring colony-forming ability” utilizing this evaluation method; and implementation of the algorithm into existing analysis systems (such as automatic colony counters).
Principal Investigator
Hiroyuki Shindo (Professor, Faculty of Engineering, Fukuoka University)
Patents & Publications
Patent:
- Pending (unpublished)