Publication Spotlight: Submerged Fermentation of Ganoderma tsugae for the Optimized Production of Exopolysaccharides
To be honest, I had never heard of Ganoderma tsugae (also known as hemlock reishi) before I read the paper "Submerged Fermentation of Ganoderma tsugae for the Optimized Production of Exopolysaccharides" Journal of Advanced Technological Education. Vol. 3, Issue 2, 2024. DOI: 10.5281/zenodo.13377110. What I discovered is that the fungus plays a significant role in Eastern traditional medicine, and thus may have potential commercial applications in cholesterol reduction, blood pressure reduction, antivirals and antitumor therapies!
However to realize this potential, the organism must be grown at scale, and its therapeutic metabolites, for example exopolysaccharide (EPS), harvested at scale. Authors Serody, Brooks, and Hewlett investigated a stirred-tank bioreactor for submerged fermentation of mycelium in order to optimize production of EPS. Ultimately, they determined that the highest biomass and EPS production was found with a lactose-based media, with constant temperature (28 degrees Celsius), pH 5.5 and agitation of 120 rpm. They carefully varied each of these fermentation characteristics, and found a few surprises along the way as well as valuable observations.
One surprise was that there were conditions that biomass weight and EPS production correlated and conditions when they did not. I assumed that the more mycelium, the more EPS, but the authors stated that perhaps during the death phase of the fungus life cycle the EPS was being consumed as a food source. A second surprise was seen when one set of conditions seemed to support a delayed, second peak of EPS production well after the initial peak at 3-4 days that most experiments exhibited. The authors stated that this second peak needs to be more fully investigated, but could have industrial applications. The authors explored the implications of organism/substrate use and what that means in the larger context of production. G. tsugae grows well with a lactose-based media, with lactose being a common waste product in food production and manufacturing. Another experimental fungal strain, G. lucidum, grew more on glucose which is not a waste product. With this in mind, the authors pursued the strain that would not only produce the required metabolite, but do it while utilizing a waste product--a valauble "win-win" scenario.
This paper provides a window into the very necessary steps from basic research to potential product. A scientific finding that cannot be adapted to production at scale will not reach its potential, so a glimpse into the some of the work needed to go from research to product is valuable indeed.
J. Serody, M. Brooks, and J. Hewlett. Submerged Fermentation of Ganoderma tsugae for the Optimized Production of Exopolysaccharides Journal of Advanced Technological Education. Vol. 3, Issue 2, 2024. DOI: 10.5281/zenodo.13377110
This work was in part supported by the National Science Foundation (NSF) under award DUE ATE #2325500.
G. tsugae stained with lactophenol cotton blue viewed under a microscope at 400x magnifcation. Lactophenol cotton blue stains chitin present in fungal cell walls.
Credit: J. Serody, M. Brooks, and J. Hewlett. DOI: 10.5281/zenodo.13377110
