Strategies for Growing Large-Scale Mycelium Structures

Round 1

Reviewer 1 Report

This article aims to expand the usage of fungi-based materials by proposing assembly strategies for building large building units in serpentine walls. The topic is essential, and I think it will interest other researchers.

 After reading the article, I have the following observations

1.       The statement in the article title "Hybrid Monolitic" is a pleonasm. Please correct. ("A strategy for Growing Big Mycelium Structures"? – A "tactic", used in the title, is a short series of actions to achieve a short-term goal)

2.       The author declares in the abstract (line 13) and the Introduction (lines 53 and 69) that he describes the research results. I find this statement too general. I propose to clarify (applied research ?, feasibility study?)

3.       The purpose of the article is imprecise. In the abstract: " This research seeks to expand upon the existing constructive paradigms of myco-structures through inquiry into assembly strategies for growing large building units and assembling them into efficiently formed serpentine wall prototypes" in the section "Introduction ", lines 53-55" This research is focused on applications of fungi-based materials at building scale, with the primary motivation being the excessive waste produced by contemporary construction practices with conventional materials "and lines 69-70" The research [described] in this paper is focused on design and building material applications of composite fungal biomass". I propose to declare the purpose of an abstract article without the words "constructive paradigms of myco-structures". Products made from these materials do not have "constructive paradigms". However, they have many limitations. One of these limitations is being overcome by the author of the article. As for the double declaration of the article's aim in the Introduction, I propose combining them into one declaration and moving it to the end of the "Introduction" section.

4.       Almost the entire subsection 1.4 (Introduction) is a summary and should be placed at the end of this article. Except for "The two methodologies tested each revisiting myco-welding and fabric-forming techniques for growing large mycelium "chucks" and assembling them into efficiently formed wall structures. A major focus was on developing intuitive and reusable formwork systems to reduce waste byproducts from growing and fabrication processes."

5.       The Conclusion section is really the Summary. There are no conclusions there, and there should be at least one, answering whether the article's declared purpose has been achieved. I propose to add this conclusion and change the section's title to "Summary and Conclusion".

6.       The article is interesting, but I encourage the author to use less pompous and more precise language. Some phrases discourage reading. For example, lines 7-8 "this emerging biotechnology has the inherent structural, isolative, and fire-resistant properties". Biotechnology has properties? I would like to add that, in my opinion, the structural properties are an "Achilles' heel" of this type of material.

7.       A sentence ending Abstract is inappropriate. The author wrote, "While tactically developing through fast-paced and improvisational making, a major concern was to design the formwork systems to be reusable." this type of sentence should be found at the beginning of the Abstract, while at the end, there should be conclusions from the actions described by the author.

 Despite these comments, I find the article interesting and worth publishing.

Author Response

Thank you for your constructive comments. My responses are attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors, Many thanks for the very interesting and important contribution. I recommend to accept your paper.

Comments for author File: Comments.pdf

Author Response

Thank you for the support and encouragement.

Reviewer 3 Report

The author is describing the practical application of the fungal bio-based composites. There is an extensive overview provided with insight into the case study of the application of the respective materials to construct the real object. This is an interesting manuscript, that falls within the scope of the journal.

Authors should avoid general populistic statements, that are not (always) true. Please avoid black-and-white statements, like plastic is bad, and renewable materials are good. For such statements, a detailed  LCA analysis should be performed. Based on the presented studies, it can not be concluded that the mycelium composites are more/or less environmentally friendly. There might be better options to utilize respective residues for construction application?

There are some case studies described, predominately from the US. However, the authors have to clearly state that there were some other similar attempts elsewhere. I am aware of some European attempts.

Be careful with fungal systematics. There are two approaches, that can not be mixed. If the authors are considering the phylum of the fungi, they should use the term Basidiomycota: https://www.britannica.com/science/Basidiomycota

L24, it is not true that the respective materials are not recyclable. Polymers are recycled on a commercial scale, the same as fibreglass. The question is whether recycling is economically feasible. But that is the problem of all materials, including the ones addressed in the respective manuscript.

L25-27, please address the risk of the respective materials. Sometimes the risk is not associated with polymers, but the phthalates in the PVC for example. It should be considered, that recycling of PVC from old windows is one of the best case studies on how recycling should be organized in Europe.

L29, end-of-life strategy depends on the region. Some regions have developed very good sorting and recycling approaches. Please be more specific. Express the good and bad examples.

L33-35, wood is one of the low-cost and affordable building materials. Forestry enables jobs in rural areas, and provides the materials for housing.

L59, mushroom cultivation could be more or less energy-demanding, depending on the region. If we want to produce the mycelium composites on a commercial scale, the growth chambers need to be heated to reach the optimal temperature.

Usually, the substrate is steam sterilized which is very expensive process.

L65, please specify plastic? What kind of polymer you have in mind?

L72, please replace the waste stream with the material stream. If there is a market for a material, it can not be considered a waste. There is a market for lignocellulosic residues, already.

L73, technically speaking the mycelium is not the root.

L74 hitin is not the only constituent of the hyphae. At lower fungi, hitin might be even absent.

L97, it should be considered that fire performance of the respective composites can be improved with the addition of fire-retardants … there have been respective attempts.

L103, what kind of mechanical load you have in mind? Compression? Tension? Are the mechanical properties important, if this composite is used for insulation?

L145, there should be space between the number and unit according to SI rules. Check through the manuscript.

L146, replace air with oxygen

L464, please specify the materials more precisely. There are 10.000s of fungi in the respective phylum. What kind of fungi was used, and how old was the substrate? How long it was incubated?

465, specify cold.

Author Response

Thank you so much for your comments. I've attached my point by point responses.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Author

All my comments have been incorporated into the article.

Sincerely

Round 3

Reviewer 1 Report

Dear Author,

All my comments are incuded in revised article.

Sincerely,

Maciej Sydor