A handy method to remove bacterial contamination from fungal cultures

PLoS One. 2019 Nov 6;14(11):e0224635. doi: 10.1371/journal.pone.0224635. eCollection 2019.

Abstract

Contamination control and removal are very important technical aspects of microbiological research. Bacterial contamination is very common in fungal cultures. Currently, the commonly used approach for inhibiting bacteria is antibiotic treatment; however, there are drawbacks to using antibiotics, including incomplete removal, limited antibacterial spectra, tendency toward recontamination, effects to fungal strains, and potential risks to the environment. Therefore, in the present work, we developed a new method for bacterial removal from fungi cultured on solid medium, the Cabin-Sequestering (CS) method, based on the different culture characteristics between fungi and bacteria. First, 3-5 mm round or square holes (the "cabin") are excavated on a solid medium plate. The fungal strain containing possible bacterial contamination is inoculated into the cabin. The cabin is then covered with a sterilized coverslip, followed by incubation at the appropriate temperature. After 7-10 days of culturing, fungal hyphae grow out along the edge of the coverslip; however, the contaminating bacteria cannot pass through the space formed between the medium and the coverslip and, thus, remain in the cabin. The newly grown fungal hyphae around the coverslip are re-inoculated into fresh culture plates, where they form bacteria-free fungal colonies. The CS method is easy handling, with a short experimental cycle and rare recontamination. When necessary, it can also be used in combination with antibiotics in bacterial removal operations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria*
  • Cell Culture Techniques / instrumentation
  • Cell Culture Techniques / methods*
  • Culture Media
  • Feasibility Studies
  • Fungi*
  • Hyphae
  • Microbiological Techniques / instrumentation
  • Microbiological Techniques / methods*

Substances

  • Culture Media

Grants and funding

This work was funded by National Natural Science Foundation of China grant number 31170136 and 31470249 to JW; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products grant number 2010DS700124-221804 to JW; National Key Research and Development Program of China grant number 2016YFD0300707; Key Technology Research and Development Program of Zhejiang province grant number 2019C02010.