Page 187 - IJB-10-5

International Journal of Bioprinting Control nutrients to manipulate fungal growth

dense mycelium network was limited to the zones of origin. the same environment and with the same nutrient levels
When the mycelium began to extend into the surrounding was observed as well. This expands on the possibility of
low-nutrient level zones, the network became sparser. This different fungi exhibiting different growth patterns on ELMs
creates a contrast in the mycelium network between the two when generalizing this technology to other strains of fungi.
zones, allowing for underlying patterns to be discernible. In While the difference between explorative and exploitative
contrast, for designs with the surrounding zones containing growth was previously investigated in literature, this was
a high nutrient level, the density of the network was higher, conducted only to optimize the concentration of malt to
eliminating the underlying pattern of the zone of origin. be included in their final ink composition. In contrast,
Owing to the inherent exploitative behavior of G. lucidum, the nutrient content in the ink used in this study was
pattern generation was more successful when this species purposely adjusted to elicit the changes in growth behavior
was used, with the letterings being distinguishable after of the mycelium at various locations of the structure. Also,
attaining complete mycelium growth on day 10. Meanwhile, the peptone was included as a second source of nutrients
since it is established that the mycelium of P. ostreatus besides malt to determine its main effect on fungal growth
tends to extend in all directions, pattern generation on the and its interaction with malt content.
surface of the substrate is less successful, despite the visible
difference in mycelium density between the high- and low- 4. Conclusion
nutrient zones. In this study, the effect of different nutrient content on
While the effect of nutrient heterogeneity on fungal the foraging behavior of mycelium was explored. With
growth was previously demonstrated in the literature, 21,27,41 two fungal strains used as case studies, their behaviors
this study significantly expands these prior discoveries. on multi-material constructs with localized variations in
Firstly, preceding studies sought to understand fungal nutrient content fabricated using DIW were investigated.
growth behavior in soil, and thus, the substrates used were In regions with low-nutrient content, both fungi exhibited
at most 2D. This study does not have such a limitation guerrilla behavior with mycelium of low density formed,
and therefore also investigates growth in all three spatial while phalanx behavior was observed in regions of
dimensions. There is also potential to utilize this knowledge high-nutrient content, resulting in the formation of
to create fungal-based ELMs and mycelium-bound dense mycelium. G. lucidum is more exploitative, with
composites of greater complexity. Regarding the creation less tendency to extend its hyphae in all directions, as
of a heterogeneous nutrient environment, previous studies compared to P. ostreatus, resulting in greater conformation
achieved this by manually arranging various cubes of to the underlying ELM. In the development of existing
agar to form a tessellation. This study utilizes modern fungal-based ELMs, this fundamental study provides
fabrication methods in the form of DIW to fabricate shapes a possibility of controlling the growth of mycelium on
with greater complexity and dimensions, in contrast to the structure using nutrients to create more complex
those with simple patterns and arrangements. This study structures with expanded functionalities. While there
also investigates how both factors of the carbon (malt) was no particular application explored in this study, it is
and nitrogen (peptone) sources interact with each other expected that the findings here will provide reference for
to affect the growth of fungi on such substrates. On the future developments towards the following applications.
contrary, previous studies either focused on comparing Improving the esthetics of apparels made using mycelium
between different media formulations 21,33,42 or only is possible by creating patterns containing either high- or
investigated a single component at a time. Finally, the low-nutrient content on the surface of such textiles. There
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application of fabricating patterned structures leveraging is also the potential of using such ELMs as a miniature
the ability to manipulate the foraging behavior of fungi model of a particular environment to model the behavior
was demonstrated in this work, underscoring the potential of fungi in said environment. This can subsequently be
utility of this phenomenon. used to better understand the capabilities and effectiveness
of using fungi to mycoremediate and remove contaminants
While the use of 3D printing to fabricate fungal-based
engineered living materials has been established, notably from the environment, or to evaluate the efficacy of anti-
by the study conducted by Gantenbein et al., this work fungal products. The 3D printing system is also capable of
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seeks to expand on their findings. In this study, instead modeling 3D ecosystems with complex shapes and is not
of a homogenous structure, multi-material samples with limited to just creating a 2D ecosystem.
heterogeneous distribution of nutrients were fabricated Beyond the investigation of malt and peptone, other
using a multi-nozzle 3D printing system. A second strain nutrient sources can also be explored as well. The effect
of fungi, P. ostreatus was explored and the difference in its of other materials on the growth and foraging behavior of
growth behavior with G. lucidum on 3D-printed ELMs in mycelium such as metal ions and other microorganisms

Volume 10 Issue 5 (2024) 179 doi: 10.36922/ijb.3939