The Addition of a Small Dose of Cinnamomum camphora Biomass Unexpectedly Enhanced Lignocellulose Degradation during the Compost of Stropharia rugosoannulata Cultivation Materials

Round 1

Reviewer 1 Report

Aromatic plant biomass (APB) were reported capable of altering the composition and function of microbial communities in many environments. However, the effects of APB addition on the compost carbon source metabolism, a process that highly linked to microbial community of compost, were still unclarified, especially when added in small doses. Here, Cinnamomum camphora biomass was added to the initial compost of Stropharia rugosoannulata cultivation materials in mass ratio of 0, 1, 2 and 3%, respectively. The variation in carbon source contents, microbial community composition and related enzyme activities of the end compost products were measured. The results showed that Cinnamomum camphora biomass addition significantly altered the content of cellulose, hemicellulose, lignin, and protein of compost products, but did not affect the starch and soluble sugar content. 

The concept is interesting and the authors explored this aspect in the present work. I have following suggestions to improve this paper.

1. Last line of abstract: Please write it at the beginning of the abstract.

2. Write a better-concluding sentence in the abstract.

3. Please introduce the concept in Introduction, this work is applicable for what kind of crops ? Are there any specific microbes associated with some specific crops?

4. Figures are too congested, please increase the size and their visibility.

5. Fig. 2 the microbial diversity was not significantly different in all treatments, why?

 

English improvement is required.

Author Response

To Reviewer 1

Thank you so much for the valuable suggestions and corrections for this manuscript. I will respond to them one by one in the following part.

1. Last line of abstract: Please write it at the beginning of the abstract.

R: We put it at the beginning of abstract

 

2. Write a better-concluding sentence in the abstract.

R: We rewrite it as “This research provides a new sight for the recycling of APB waste and offered an improvement to the mushroom cultivation material compost.”

 

3. Please introduce the concept in Introduction, this work is applicable for what kind of crops ? Are there any specific microbes associated with some specific crops?

R: This research is mainly about the cultivation material fermentation improvement aiming to the Stropharia rugosoannulata, a mushroom. Up to date, the plant crop rhizosphere microbes were popularly investigated while the mushroom crop “rhizosphere” microbes were few explored. We believe that there would be certain specific microbes interacting with the host and promote the nutrient assimilation.

 

4. Figures are too congested, please increase the size and their visibility.

R: We adjusted the size of the pictures.

 

5. Fig. 2 the microbial diversity was not significantly different in all treatments, why?

R: In this research, composition was significantly altered while diversity was not, which indicated a trade-off of dominating taxa during the composting, and considerable rare taxa was remained during compost, thus high richness and diversity appeared in every stages. Diversity may decrease, increase and unchanged during compost, which was controlled by detailed compost processes.

 

Thank you again for your suggestions and corrections, they do helped a lot in improving the paper’s quality, especially abstract parts.

Reviewer 2 Report

The manuscript sustainability-2405371 by Zhou et al. investigated the impact of aromatic plant biomass (APB) i.e., Cinnamomum camphora on the composition and functioning of microbial communities, for the compost carbon source metabolism. The manuscript is very interesting and well prepared. Please improve the quality of Figure 3A and of x-axis text in 3B. Also, modify L212 as treatments, (plural).

N/A

Author Response

R: Thank you for your valuable suggestions, we modified the picture and correct the line 212 as “The carbon sources and enzyme activities of different treatment. C indicates control while A1, A2 and A3 indicate 1, 2 and 3% Cinnamomum camphora biomass added treatment, respectively. The a, b, c and d above the bars indicates significance of differences among treatments, one-way ANOVA Turkey’s HSD (P<0.05). LiP and MnP are abbreviations for lignin peroxidase and magnesium peroxidase, respectively.”

Reviewer 3 Report

Comments on the review are in the manuscript version in pdf file.

Comments for author File: Comments.pdf

Author Response

Dear reviewer 3:

Thanks so much for your detailed and helpful corrections and suggestions, they really helped us a lot in improving the quality of this work, and we’ll response to the comments one by one.

 

Commented [M1]: APB waste management is the central issue of the manuscript. However, an overview of the production of APs is not presented, as well as the volume of APBs waste generated.

Authors must contextualize aspects of the APBs production chain to strengthen the issue and/or central motivation for carrying out the study.

R: We added “For instance, over 6.7× 10⁴ hectares of Cinnamomum camphora were cultivated only in China since 2019, and more than 98% Cinnamomum camphora biomass became waste after industrial extraction, which indicated a huge aromatic plant biomass waste production annually [22].” in Line 47 to quantify the yielding the waste production.

 

 

Commented [M2]: Changes are expected to occur in the microbial community.

R: We changed as “the small dose addition of APBs” to focus the real question, thanks.

 

Commented [M3]: Please organize this information in a table. The cellulose, lignin and hemicellulose contents of APB residues must also be entered in the table.

R: We changed this description as table 1 accordingly, thanks for the suggestion.

 

Commented [M4]: Was this cover sufficient to prevent gas exchange in the compost pile?

If this occurred, there was favoring anaerobiosis, which impacted the compost quality.

R: The plastic membrane is not gas permeable, and can prevent water evaporation, help keep moisture of the material. But the compost should mainly be aerobic fermented, as compost were remixed with air thoroughly several times, though anaerobic process also happened. This comment inspired us to change another gas permeable membrane for the compost, maybe we can get more excited results next time. Thank you so much!

 

Commented [M5]: Were these parameters measured in the residues of Cinnamomum camphora?

R: The parameters were the basic pH, original nutrient element content of materials, which comprised by bamboo litters, hardwood litters, etc.

 

Commented [M6]: What is the C/N ratio? How can this C/N ratio impact the other parameters of the compound?

R: We didn’t focus on the C:N ratio of Cinnamomum camphora biomass, as the additive quantity of it is low, only 3% mass ratio of Cinnamomum camphora biomass were added even in high additive treatment. And as a kind of hardwood, Cinnamomum camphora biomass should like other hardwood litters. And we hypothesize that the secondary metabolite maybe the main cause for the variation on microbial community and carbon source cycling. That’s why we didn’t measure the C:N ratio of Cinnamomum camphora biomass.

 

Commented [M7]: The use of APB residues does not seem to be a good alternative for stabilizing the carbon in the compost.

R: Yes, the LiP activity was decreased, while the laccase activity increased. The APB reshaped the dominating functional groups and helped lower the macromolecular recalcitrant carbon source, that’s its merit. Yet, we still need further investigation to maximize the stimulative effect on carbon source degradation effects.

 

Commented [M8]: What is the lignin content of C. camphora?  What is the contribution of C. camphora residues to the final quality of the compost. Good quality compost should have higher levels of labile carbon sources for better growth of S. rugosoannulata. The addition of C. camphora residues does not seem to be a good alternative for a compost material to cultivate fungus.

R: The lignin content of C. camphora is about 30%, yet, the quantity added is tiny, so this won’t lead significant change on lignin content of the material, The residue addition lowered the content of lignin, cellulose and hemicellulose of final compost products, which may facilitate the fungal cultivation. We originally supposed that the soluble sugar should be increased as the recalcitrant carbon contents were decreased by the addition of C. camphora, However, unfortunately, the soluble sugar content was not significantly altered. We don’t know the reason and it does frustrate us a lot. But considered that the carbon source metabolism is highly complexed and is complicatedly linked to microbial processes, we think that there must be other optimal ways to be found to stimulate both recalcitrant carbon degradation and labile carbon accumulation.

 

Commented [M9]: Waste management is important. However, it does not seem to be the best alternative to compost C. camhora waste to obtain a compost for growing the fungus.

R: Yes, the directly compost aromatic plant biomass to get mushroom cultivation materials seems not so good, but we only add the C. camhora waste as extra additive. The result showed that the additive could enhance the degradation of macromolecular recalcitrant carbon, and thus may facilitate the mushroom nutrient assimilation. Yet, there still needs to be further studied to get the best ratio of every material components, and isolated the specific microbes to stimulate the accumulation of labile carbon, which may enhance the mushroom yielding in step.

 

Lastly, thank you so much again for the detailed suggestions and corrections, we feel so sorry that several questions are out of our current knowledge and we can’t give plausible answers now. We’ll keep doing research in this field, and maybe we can answer the questions oneday in the future.

Reviewer 4 Report

The manuscript entitled “The small dose addition of Cinnamomum camphora biomass unexpectedly enhanced the lignocellulose degradation during the compost of Stropharia rugosoannulata cultivation materials” reports the studies on the effect of the addition of  Cinnamomum camphora biomass to the initial compost of Stropharia rugosoannulata cultivation materials. The influence was measured in terms of variation in carbon source contents, microbial community composition and related enzyme activities of the end compost products. The results showed that Cinnamomum camphora biomass addition significantly altered the content of major plant polymers of compost products, but did not affect the starch and soluble sugar content. The presented work claims to provide new insight into the recycling of aromatic plant waste and the improvement of mushroom cultivation material compost.

 

The paper shows a few interesting analyses which can help in improving the process of mushroom industry development.

There are a couple of queries/suggestions as mentioned below.

(1)  Line 114: How the 60% moisture content of compost materials was measured?

(2)  Figure 3b: On the y-axis, the effects are in terms of the fold?

 

(3)  What is the influence of the addition of Cinnamomum camphora biomass on fruiting bodies of mushrooms and final yield?  

Author Response

Thanks for your valuable suggestions, they do make this manuscript more concise and scientific. We’ll response accordingly.

• Line 114: How the 60% moisture content of compost materials was measured?

R: The technicians adjust the moisture by their experience, mainly by press the watered materials and see how much water can be squeezed, and whether the pressed materials can automatically return to original state in certain time. So, the moisture was only about “60% moisture”

• Figure 3b: On the y-axis, the effects are in terms of the fold?

R: The standard effects were mainly ranged between -1 to 1, them are not folds.

• What is the influence of the addition of Cinnamomum camphora biomass on fruiting bodies of mushrooms and final yield?  

R: We only found weakly increasing trend (not significant) on yielding, considered the yielding is not the core part of this research, we didn’t describe the yielding results here. But we found the addition of APB lead more delicious mushroom. And we still need systematic research to elucidate the relationship between materials, microbial community, yielding and flavor secondary metabolite accumulations.