Combined Dairy Manure-Food Waste Digestate as a Medium for Pleurotus djamor—Mineral Composition in Substrate and Bioaccumulation of Elements in Fruiting Bodies

Round 1

Reviewer 1 Report

The current manuscript entitled “Bioaccumulation of Elements in Pleurotus djamor Mushroom Fruiting Bodies Cultivated on Combined Dairy Manure-food Waste Digestate and the Residual Elemental Content in Spent Mushroom Substrate” by Jasinska et al. deals with a detailed study on analysis of 38 elements in the mushroom compost and fruiting bodies. After a careful reading, I found this manuscript very interesting and suitable for publication in the Horticulturae journal. The experiments are conducted wisely and the reported results are well acceptable. However, I would like to suggest some moderate changes in the current version. I suggest a major revision. My specific comments are:

1.      Title change: Bioaccumulation of Selected Elements in Pink Oyster (Pleurotus djamor) Mushroom Cultivated on Dairy Manure-food Waste Digestate and the Spent Mushroom Substrate.

2.      Mention the strain of Pleurotus djamor in both abstract and methods.

3.      Line22: Experimental sites are not necessary for abstract. They seem to be fine under methods only.

4.      L20: Change “employing” to “by using”.

5.      L27: three flushes, and delete (I, II, and III).

6.      Several abbreviations are not defined at their first use. Avoid abbreviations in the keywords.

7.      L170: provide strain and spawn collection sites.

8.      What system did the authors use for climate control?

9.       Reference missing for analytical works.

10.   80-120% recovery is not fine for ICP instruments. Herein, the error is very high i.e., 20%.

11.   P. djamor is not italicized in several places.

12.   The table and figure captions are poorly written with no logical information. Extend them to provide more relevant information about the data provided.

13.   I suspect about the Cr content in the fruiting bodies of P. djamor. Mushrooms hardly accumulate <2 mg/kg DW of Cr. Also, the safe limit of Cr in mushrooms is 2.3 mg/kg DW. Authors must justify these results.

14.   Why do the levels of elements increase in later harvested mushrooms? Mycelia becomes weak with time and thus their capacity also decreases.

15.   Bioconcentration factors>1 are considered to be toxic for humans, especially in the case of potentially toxic elements, how do authors justify this?

16.   The manuscript should be checked for grammatical and syntax errors carefully.

Author Response

Respected reviewer,    Thank you very much for your time reflected for reviewing our manuscript. Youc comments were very valuable, below you will find our answers:

1. We elaborated the title and changed it for: "Combined Dairy Manure-food Waste Digestate as a Medium for Pleurotus djamor  -  Mineral composition in substrate and Bioaccumulation of Elements in Fruiting Bodies"
2. Mention the strain of Pleurotus djamor in both abstract and methods. MENTIONED

3.      Line22: Experimental sites are not necessary for abstract. They seem to be fine under methods only. CORRECTED

4.      L20: Change “employing” to “by using”. CORRECTED

5.      L27: three flushes, and delete (I, II, and III). CORRECTED

6.      Several abbreviations are not defined at their first use. Avoid abbreviations in the keywords. CORRECTED

7.      L170: provide strain and spawn collection sites. CORRECTED

8.      What system did the authors use for climate control? 

INFORMATION ON THE CULTIVATION CONDITIONS ARE IN SUPPLEMENTARY FILES.

9.       Reference missing for analytical works. CORRECTED

10.   80-120% recovery is not fine for ICP instruments. Herein, the error is very high i.e., 20%.

Thank you for your mention, however this values are correct.

11.   P. djamor is not italicized in several places. CORRECTED

12.   The table and figure captions are poorly written with no logical information. Extend them to provide more relevant information about the data provided. CORRECTED

13.   I suspect the Cr content in the fruiting bodies of P. djamor. Mushrooms hardly accumulate <2 mg/kg DW of Cr. Also, the safe limit of Cr in mushrooms is 2.3 mg/kg DW. Authors must justify these results. 

Thank you for your vigilance, after your suggestion we have double checked our results, and we found an error in calculations and folding results in Excel, which was fixed. After recalculating the results we have the values of 0.34 to 0.42 ppm in mushroom fruiting bodies."

14.   Why do the levels of elements increase in later harvested mushrooms? Mycelia becomes weak with time and thus their capacity also decreases. -

Thank you for your comment, as for our knowladge there are no published studies on levels of elements in subsequent mushroom harvestm therefore our hyphotesis is that there is a loss of substratres DM during the growing period as well as due to its metabolism and removal of substances from the substrate for the construction of the fruit body (Rajarathnam and Bano, 1992). - Written in the text. 

15.   Bioconcentration factors>1 are considered to be toxic for humans, especially in the case of potentially toxic elements, how do authors justify this? 

Actually, BCF measures the relationship between the metal concentration in mushrooms and the metal concentration in the underlying soil where mushrooms grow; a BCF>1 indicates an accumulation of metal ions by the mushrooms while a BCF<1 shows that the mushrooms are bioexclusors of the metal ions. So it is showing how good mushroom is in accumulating certain element. If the element in fungi is toxic for humans or not, the estimated daili intake (EDI) is more informative, becasue it explains on how much of the element from the mushroom can be safely consumed by humas.

16.   The manuscript should be checked for grammatical and syntax errors carefully. CORRECTED

Reviewer 2 Report

First of all, I would like to thank Horticulturae editorial office for choosing me as a reviewer. The manuscript is an attempt of a multi-elemental analysis of elements employing inductively coupled plasma optical emission spectrometry (ICP-OES) in EMS, mushroom fruiting bodies and SMS. The information presented in the manuscript is interesting. The amount of data presented is adequate to understand and interpret its scientific content. However, the manuscript needs review wording and journal style, in such form is difficult to read and accept.

I have some doubts and suggestions after reading manuscript:

-          Line 8-13: seems incorrect, double check.

Abstract:

-          Improvement of abstract with more informative and concise is needed.

-          Line 41: they----> mushroom cultivation or agro- and industrial waste residues, unclear.

-          Introduction: For me, the introduction seems verbose – rewrite and put the authors’ interest in conducting research concisely.

Materials and methods:

-          It is more interesting for readers, if the authors could put the picture or figure of the climate-controlled mushroom growing chamber.

-          I do not find ethical statement thorough the manuscript.

-          Line 179-180: so, what is authors’ manure used? Dairy or chicken or mixed of which?

-          Line 211-212: The format is inconsistent with earlier.

-          Line 287: what do the authors mean of non-traditional substrate?

Results: unclear about the treatments used EMS vs SMS; Flush 1, 2, 3, those are from the mean of EMS or SMS?

Discussion:

-          Lines 433-454: Improvement with using relevant references is needed.

-          Lines 472-506: Improve these paragraphs with using relevant references.

-          Lines 516-562: Improve these paragraphs with using relevant references.

-          Lines 566-617: Improve these paragraphs with using relevant references.

-          Lines 619-682: Improve these paragraphs with using relevant references.

Conclusion: Put the most current study findings and clear implication - rewrite.

 

References:

-          could the authors reduce the references up to 50 – 60?

-          Could the author use the MDPI refence style?

Author Response

Reviewer 2: 

Respected reviewer, thank you for your time comited to review and comment our manuscripts. The correction and our answers are listed below:

Line 8-13: seems incorrect, double check. CORRECTED

Abstract:

Improvement of abstract with more informative and concise is needed. CORRECTED

Linene 41: they----> mushroom cultivation or agro- and industrial waste residues, unclear. CORRECTED

Introduction: For me, the introduction seems verbose – rewrite and put the authors’ interest in conducting research concisely.

CORRECTED

Materials and methods:

It is more interesting for readers, if the authors could put the picture or figure of the climate-controlled mushroom growing chamber.

Thank you for the comments, but the cultivation method was not the subject of the study, therefore we do not think pictures or figures of the chamber are necessary. 

I do not find ethical statement thorough the manuscript.

No need for ethical statement. Int the research no human, animal, cell lines, no rare plants of fungi, or clinical trials were involved in the study. Thus, ethical statement is not needed. 

Line 179-180: so, what is authors’ manure used? Dairy or chicken or mixed of which? CORRECTED 

Line 211-212: The format is inconsistent with earlier. CORRECTED

Line 287: what do the authors mean of non-traditional substrate? INFO ADDED

Results: unclear about the treatments used EMS vs SMS; Flush 1, 2, 3, those are from the mean of EMS or SMS?  

CORRECTED and necessary additional info added

Discussion:

Thank you for your comments, however I must underline that the published studies and research on the digestate based substrate mushroom cultivation are limited, also a very limited amount of information deals with mineral content of the cultivation substrates, SMS or the fruiting bodies from this type of cultivation. Therefore, we think the discussion uses relevant references for justifying the results and not comparing with substrates which are completely different in composition, or with not relevant mushroom species. 

Also, the yield was not the subject of the experiment, but only means for obtaining the fruiting bodies and calculations for minerals content. Therefore, this section is described as short and adequate for the importance of it for the manuscript. 

Conclusion: Put the most current study findings and clear implication - rewrite.

References:

 could the authors reduce the references up to 50 – 60?  

As the MS is novel in this regard, the most recent and relevant references are used through the MS and reducing the list of references to 60 will be quite difficult.

Reviewer 3 Report

In this manuscript, are present a plausible approach for using the combined digestate from dairy manure and food waste as a potential substrate for the cultivation of P. djamor to achieve comparable yields and BE.

Considering the questionability of using such non-traditional substrates (digestate) in mushroom production, this study also calculated the estimated daily intake (EDI), which reflected that the P. djamor fruiting bodies grown on EMS can serve as an excellent source of Ca, Mg and Na (MEE’s), Mn, Mo, Ni and most importantly Se and Zn (ETE’s) which are noteworthy. On the other hand, EDI values for K, Cu, Fe, Ag, Ba, Cd, Al, Sb and Sr were greater than the referred guideline values corresponding to higher intake and associated risks.

The manuscript is well formulated. The results are presented clearly and they are well discussed. The manuscript is meaningful, organized and therefore I recommend it for publication in the Horticulturae.

Author Response

Respected reviewer, we would like to thank you for your time commited to read, review and comment our research described in the manuscript. 

Sincelry,

Round 2

Reviewer 1 Report

Dear Authors, I checked revised version of your manuscript. All queries/corrections are addressed as per my comments but I still suspect about the Cr contents. If this was mistake in calculations, the readings must have been corrected in table 4 as well as in whole text. Table 4 still contains Cr values higher than 30. Moreover, the study of Zsigmond et al. (line 509) reported Cr of 40 mg/kg which is not even close to your result (0.28-0.35 mg/kg). I suggest deleting this statement that these results are in line with your findings. On the other hand, the values of bioaccumulation factor and risk assessment indices should also be revised as a result of change in overall Cr value.

Author Response

Dear Reviewer,

Thank you once again for your comments, the corrections were made and addressed as advised. 

Reviewer 2 Report

With all due respects, the authors' response is difficult to follow. The way to mention "CORRECTED" with no line number that is inappropriate.
I give you the second chances to revise your manuscript.

Author Response

Dear Reviewer, 

Please find attached file with the corrections and comments. 

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

All questions and concerns are answered to enhance the paper quality by authors. I recommend this paper as accept in present form.

Best wishes