Page 182 - IJB-10-5

International Journal of Bioprinting Control nutrients to manipulate fungal growth

Figure 2. Nutrient concentration controls the foraging behavior of P. ostreatus (top panels) and G. lucidum (bottom panels). (A) Digital images of mycelium
grown on agar plates containing varying concentrations of malt and peptone after 14 days of culture following the two-level full factorial design (see
Materials and methods section for details). Scale bars: 20 mm. (B) Growth area of the mycelium during 14 days of culture for the four different nutrient
compositions. (C) Dry biomass per unit area of the mycelium sheets harvested after 14 days of culture for the four nutrient compositions. Data are
presented as mean ± standard deviation. *p <0.05, **p <0.01. Abbreviations: H, high; L, low; M, malt; P, peptone.

but both malt and peptone complemented each other. This as described in the previous sections were analyzed using
synergy resulted in a statistically significant increase in electron microscopy (Figure 3).
absolute dry biomass obtained when the concentration of The microstructures of the mycelium sheets grown after
peptone was increased at high levels of malt concentration. 14 days (Figure 3A) are consistent with the macroscopic
While malt promoted a greater increase in dry biomass observations made from mycelium grown on agar plates
obtained, this quantity increased further in the presence of (Figure 2A). The density of the mycelium of both P. ostreatus
high levels of peptone. and G. lucidum increased when the concentration of malt
The variation in malt and peptone concentrations was increased. At low malt and peptone concentrations,
demonstrated various foraging behaviors for the two fungi there were visible gaps in the network for both strains but as
studied here. This difference in growth led to mycelium the concentration of nutrients increased, there was tighter
formation with differing macroscopic appearances, which packing of the hyphae, owing to the increased mycelium
could readily influence their properties. A microscopic density due to the higher occurrence of branching.
characterization of the mycelium was therefore conducted The surface porosity and projected hyphae diameter
to better understand the implications of the varying were also evaluated from these electron micrographs.
growth rates. The surface porosity was significantly reduced when the
concentration of malt available to the mycelium increased
3.3. Tuning nutrient concentration allows for various (Figure 3B). This holds true for both strains regardless of
morphology of the mycelium of P. ostreatus and the concentration of peptone. Meanwhile, peptone had
G. lucidum a significant influence on the reduction of the surface
To determine the effect of the nutrients and the growth porosity of the mycelium of P. ostreatus, but its effect
rates on the morphology of the mycelium of the two fungi, on the microstructure was negligible for G. lucidum. In
the mycelium sheets grown in the four nutrient conditions turn, both malt and peptone had a positive effect on the

Volume 10 Issue 5 (2024) 174 doi: 10.36922/ijb.3939