Plant Essential Oils as Biocides in Sustainable Strategies for the Conservation of Cultural Heritage

Round 1

Reviewer 1 Report

The essential oils of aromatic plants mostly used as well-known biocides for medical/pharmaceutical and food usage. And these natural compounds do not alter the artworks nature, are mainly non-toxic to humans and environment, being an eco-sustainable approach. In this review, plant extracts and their usage (control of microbial degradation of cultural heritage) are assessed with reference to recent research on plant essential oils. This article covers a wide range of literature, but there is some confusion in the writing of the paper. Especially in part 2, 3, and 4, I suggest that the paragraphs be divided either by the type of plant, by the type of microorganism, or by the type of artifact. Additionally, there are slightly more keywords, so I suggest reducing them.

Author Response

Reviewer 1

The essential oils of aromatic plants mostly used as well-known biocides for medical/pharmaceutical and food usage. And these natural compounds do not alter the artworks nature, are mainly non-toxic to humans and environment, being an eco-sustainable approach. In this review, plant extracts and their usage (control of microbial degradation of cultural heritage) are assessed with reference to recent research on plant essential oils. This article covers a wide range of literature, but there is some confusion in the writing of the paper.

Especially in part 2, 3, and 4, I suggest that the paragraphs be divided either by the type of plant, by the type of microorganism, or by the type of artifact. Additionally, there are slightly more keywords, so I suggest reducing them.

1. We divided paragraphs by the type of artifact (organic and inorganic). It was difficult divide by type of plants or microorganism, they are common to many articles. For example, Thyme (in addition with other EOs) was used on many different cultural heritage and against different microorganisms (see table 2).

 

1. We reduced keywords, as suggested.

Reviewer 2 Report

The topic of manuscript is quite interesting. But title is very lengthy. It can be reduced. The paper reflects & discusses about some essential oil yielding plants with potent antimicrobial activity.

The english language is fine. Only minor checking is required.

Author Response

Reviewer 2

The topic of manuscript is quite interesting. But title is very lengthy. It can be reduced. The paper reflects & discusses about some essential oil yielding plants with potent antimicrobial activity. The english language is fine. Only minor checking is required.

1. We reduced the title and english revision was done.

Reviewer 3 Report

The presented review is quite interesting, compiling a good amount of available information that will surely be of interest to your readers. However, there are some issues that need attention before the article can be published.

Overall, the writing needs to be revised. Particularly in the introduction section, the sequence and articulation of sentences need to be reviewed so that the intended message is effectively conveyed. For instance, in the first paragraph where it is stated that "cultural heritage includes several typologies of historic artistic artworks, as well as intangible and natural heritage (landscapes and biodiversity)," followed by "Cultural heritage is made up of the most variable materials…," there is no clear differentiation between natural and man-made heritage. Everything is referred to as cultural heritage, and only human-made heritage could be "made up of the most variable materials". Another example is found in the next sentence where it states that "In fact, cultural heritage undergoes to biodeterioration by micro/macro-organisms or physical and chemical agents, that cause changes in their materials with evident aesthetic alterations." If we talk about "bio" deterioration, it is not "or physical and chemical" but rather the inherent alteration caused by the mentioned micro and macro-organisms, which may result from chemical or physical processes due to their presence… If we talk about deterioration, it can be caused by physical, chemical, and biological factors (micro and macro-organisms). Furthermore, in the following paragraph "The types of biodeterioration are also due to several factors, such as the natural/chemical composition of the material, the physical conditions of the environment (climate, temperature, lighting), the cleaning and maintenance methods…" is presented a mixture of distinct information that is confusing. What is presented is not the types of “biodeterioration” (in a rough sense, physical, chemical, and aesthetic), but rather some of the factors that will influence this process, whether they are intrinsic to the materials (such as their composition), extrinsic (such as environmental conditions), anthropogenic (resulting from human activities, such as cleaning), among others. This section needs to be thoroughly reviewed, and the terms used should be carefully and accurately applied according to their respective meanings.

These kinds of inconsistencies in writing and information presented need to be addressed throughout the entire text to ensure that the reader receives the intended message.

Also, in the introduction section, there is a discussion of organisms causing material alteration (L42 to 52), narrowing down to the specific case of fungi, followed by an information table. Some studies where these organisms (bacteria, archaea, fungi, insects, etc.) have been identified associated with deterioration processes should be included to substantiate what is said. Alternatively, a column could be added in Table 1, including references for information provided on these organisms (similar to what is done in Table 2).

Regarding Table 1, in the line of fungi, it says "Rizine action." Rizine?? Perhaps you meant "hyphae"?

In section "Antimicrobial effects of Essential oils: in vitro assays" on line 158, it is stated that "Several studies have been conducted in order to test the antimicrobial activity of many plant extracts against microorganisms (such as fungi, bacteria, and insect pests) associated with biodeterioration in archives, libraries, museums and external/outdoor monuments [2]." Is this the correct and intended reference for what is being said?

Finally, throughout the different sections where various studies on the use of essential oils are mentioned, many times it is stated that a particular study was conducted to test a specific oil, without further alluding to the final result of the study. For example, "O. vulgare EO has been tested against seven Aspergillus species isolated from different cultural heritage substrata (paper, silk, and stone) in Serbia, even comparing its biocide activity with commercial products [54]." So, what did they conclude? Is it the same? Better? Even if briefly summarized, the study and the main conclusion should be indicated. Additionally, the species name should be written in full at the beginning of sentences, rather than abbreviated. These aspects should be reviewed throughout the text.

The comments regarding the quality of English are indicated in the above section "Comments and Suggestions for Authors".

Author Response

Reviewer 3

The presented review is quite interesting, compiling a good amount of available information that will surely be of interest to your readers. However, there are some issues that need attention before the article can be published.

Overall, the writing needs to be revised. Particularly in the introduction section, the sequence and articulation of sentences need to be reviewed so that the intended message is effectively conveyed. For instance, in the first paragraph where it is stated that "cultural heritage includes several typologies of historic artistic artworks, as well as intangible and natural heritage (landscapes and biodiversity)," followed by "Cultural heritage is made up of the most variable materials…," there is no clear differentiation between natural and man-made heritage. Everything is referred to as cultural heritage, and only human-made heritage could be "made up of the most variable materials". Another example is found in the next sentence where it states that "In fact, cultural heritage undergoes to biodeterioration by micro/macro-organisms or physical and chemical agents, that cause changes in their materials with evident aesthetic alterations." If we talk about "bio" deterioration, it is not "or physical and chemical" but rather the inherent alteration caused by the mentioned micro and macro-organisms, which may result from chemical or physical processes due to their presence… If we talk about deterioration, it can be caused by physical, chemical, and biological factors (micro and macro-organisms). Furthermore, in the following paragraph "The types of biodeterioration are also due to several factors, such as the natural/chemical composition of the material, the physical conditions of the environment (climate, temperature, lighting), the cleaning and maintenance methods…" is presented a mixture of distinct information that is confusing. What is presented is not the types of “biodeterioration” (in a rough sense, physical, chemical, and aesthetic), but rather some of the factors that will influence this process, whether they are intrinsic to the materials (such as their composition), extrinsic (such as environmental conditions), anthropogenic (resulting from human activities, such as cleaning), among others. This section needs to be thoroughly reviewed, and the terms used should be carefully and accurately applied according to their respective meanings.

These kinds of inconsistencies in writing and information presented need to be addressed throughout the entire text to ensure that the reader receives the intended message.

Also, in the introduction section, there is a discussion of organisms causing material alteration (L42 to 52), narrowing down to the specific case of fungi, followed by an information table. Some studies where these organisms (bacteria, archaea, fungi, insects, etc.) have been identified associated with deterioration processes should be included to substantiate what is said. Alternatively, a column could be added in Table 1, including references for information provided on these organisms (similar to what is done in Table 2).

1. A) We revised all the manuscript sections as rightly suggested by the reviewer, and added references to table 1.

Regarding Table 1, in the line of fungi, it says "Rizine action." Rizine?? Perhaps you meant "hyphae"?

1. We corrected table1 and deleted this part.

In section "Antimicrobial effects of Essential oils: in vitro assays" on line 158, it is stated that "Several studies have been conducted in order to test the antimicrobial activity of many plant extracts against microorganisms (such as fungi, bacteria, and insect pests) associated with biodeterioration in archives, libraries, museums and external/outdoor monuments [2]." Is this the correct and intended reference for what is being said?

1. We changed the reference that was incorrect.

Finally, throughout the different sections where various studies on the use of essential oils are mentioned, many times it is stated that a particular study was conducted to test a specific oil, without further alluding to the final result of the study. For example, "O. vulgare EO has been tested against seven Aspergillus species isolated from different cultural heritage substrata (paper, silk, and stone) in Serbia, even comparing its biocide activity with commercial products [54]." So, what did they conclude? Is it the same? Better? Even if briefly summarized, the study and the main conclusion should be indicated. Additionally, the species name should be written in full at the beginning of sentences, rather than abbreviated. These aspects should be reviewed throughout the text.

1. A) We implemented the manuscript sections as suggested by reviewer, describing better the results of each study.

Reviewer 4 Report

The review focus on summarizing the studies that addressed the use of essential oils to avoid biodeterioration of cultural heritage. Although some recent reviews addressed similar subject, the focus on EO is unique and the text is well written and interesting. Nevertheless, to be accepted, the manuscript should undergo improvement, as suggested:

An item describing database screening and search criteria should be presented in order to the reader fell sure that the literature was covered.

Table 1 should contain a footnote with the references used that allowed this knowledg (association between the biological systems x physical damages x chemical damages x materials)

Section “Antimicrobial effects of Essential oils: in vitro assays” was not numbered, is not part of section 2 and, as a matter of fact, seems out of context. The in vitro assays do not cover, for sure, all in vitro assays with antimicrobial purposes done with EO. Some paragraphs do not disclose whether the study was performed with a human pathogen of a pathogen more often found in cultural heritage, that do not seem to be the same. In fact, it would be more interesting if the authors compiled the pathogens found in the review (including a column in Table 2) and, e.g., provided a pie chart with the distribution of microorganisms (it could be two, one for organic and the other inorganic cultural assets) so that the reader can observe the most prevalent microorganisms associated with these biodegradation.  

A pie chart demonstrating the country of origin of these studies would be interesting as well, so that one can make correlations of the places where the sustainable use of EO in cultural heritage conservation is being studied, if that is related with the existence of historic monuments, and so on). In fact, the review lacks some data discussion based on the findings distribution. 

Please cite the recent review of Kakakhel et al. (https://doi.org/10.1016/j.ibiod.2019.104721) that is closely related to this topic, showing the differences with your review. 

 

Author Response

Reviewer 4

The review focus on summarizing the studies that addressed the use of essential oils to avoid biodeterioration of cultural heritage. Although some recent reviews addressed similar subject, the focus on EO is unique and the text is well written and interesting. Nevertheless, to be accepted, the manuscript should undergo improvement, as suggested:

An item describing database screening and search criteria should be presented in order to the reader fell sure that the literature was covered.

1. We described databases and search criteria at the end of the introduction section.

Table 1 should contain a footnote with the references used that allowed this knowledg (association between the biological systems x physical damages x chemical damages x materials)

1. We added references in table1, as rightly suggested.

Section “Antimicrobial effects of Essential oils: in vitro assays” was not numbered, is not part of section 2 and, as a matter of fact, seems out of context. The in vitro assays do not cover, for sure, all in vitro assays with antimicrobial purposes done with EO. Some paragraphs do not disclose whether the study was performed with a human pathogen of a pathogen more often found in cultural heritage, that do not seem to be the same. In fact, it would be more interesting if the authors compiled the pathogens found in the review (including a column in Table 2) and, e.g., provided a pie chart with the distribution of microorganisms (it could be two, one for organic and the other inorganic cultural assets) so that the reader can observe the most prevalent microorganisms associated with these biodegradation.  A pie chart demonstrating the country of origin of these studies would be interesting as well, so that one can make correlations of the places where the sustainable use of EO in cultural heritage conservation is being studied, if that is related with the existence of historic monuments, and so on). In fact, the review lacks some data discussion based on the findings distribution. 

1. We numbered the section “Antimicrobial effects of Essential oils: in vitro assays”. This section was written precisely because, reading the articles, we realized that authors did not declare from which artefacts the microorganisms were extracted, suggesting that they used microorganisms grown in vitro in the laboratory. Sometimes they were vague. This is the reason why we made a separate section. However, at the beginning of this paragraph we tried to explain briefly the reason of this part.

 

1. We provided table 3 and table 4 to describe microorganisms isolated from artefacts, described in this review, considering that most microorganisms can be pathogenic, directly or indirectly, for humans. Moreover, a pie chart with the countries of origin of the studies included in this review was reported.

Please cite the recent review of Kakakhel et al. (https://doi.org/10.1016/j.ibiod.2019.104721) that is closely related to this topic, showing the differences with your review. 

1. We added the suggested citation.

Round 2

Reviewer 3 Report

The authors have made the changes and corrections as proposed to them. Below, I include some further corrections and suggestions that still require attention:

L46-47 – "...they contain inorganic compounds such as salts due to manufacturing procedures and/or inorganic substances from inks." Please confirm if both cases should be inorganic.

L70-71 – "Also in outdoor systems, however, monitoring the status of artwork should not be underestimated." This sentence needs to be revised to make sense. Consider using something similar: " Also, in outdoor systems, although it may be difficult to monitor and control all the factors that impact the biodeterioration process, it is essential not to underestimate the significance of monitoring the condition of historical assets"

Section 4. Antimicrobial activity of EOs on organic cultural asset – The following referenced studies still do not include the final remarks (conclusions reached at the end of the essay): Study from L209 to L213; Study from L213 to L215; Study from L225 to L228; and finally, the study from L233 to L236.

L300 – "...and wooden substrata..." This mention does not make sense in the section dedicated to inorganic materials.

L382 – C. zeylanicum is in bold and lacks italics.

L387-396 – The entire paragraph about food does not make any sense to be included in an article focusing on cultural heritage.

L412 – "...referred to..." is duplicated.

Table 3 and 4 – Some information is missing in these tables, e.g., Stachybotrys chartarum, considered one of the top 10 most dangerous fungi, has been identified in heritage sites.

Please review and address these issues accordingly.

There are still some minor writing errors that need to be corrected, such as:

L36-37 - "In fact, they undergoes to different deterioration processes..." refers to cultural heritage, so it would be more appropriate to say "these assets" or "these materials" or something similar.

L38 - "such as micro/macro-organisms (biodeterioration), or by physical and chemical agents..." It should be "and" instead of "or" to indicate that both micro/macro-organisms and physical and chemical agents can contribute to deterioration (in a synergistic manner).

This review should be applied throughout the entire text.

Author Response

Response to reviewer Comments and Suggestions for Authors

 The authors have made the changes and corrections as proposed to them. Below, I include some further corrections and suggestions that still require attention:

 

L46-47 – "...they contain inorganic compounds such as salts due to manufacturing procedures and/or inorganic substances from inks." Please confirm if both cases should be inorganic.

1. It is confirmed.

 

L70-71 – "Also in outdoor systems, however, monitoring the status of artwork should not be underestimated." This sentence needs to be revised to make sense. Consider using something similar: " Also, in outdoor systems, although it may be difficult to monitor and control all the factors that impact the biodeterioration process, it is essential not to underestimate the significance of monitoring the condition of historical assets"

1. A) Changed as suggested.

 

Section 4. Antimicrobial activity of EOs on organic cultural asset – The following referenced studies still do not include the final remarks (conclusions reached at the end of the essay): Study from L209 to L213; Study from L213 to L215; Study from L225 to L228; and finally, the study from L233 to L236.

1. A) Added the final remarks.

 

L300 – "...and wooden substrata..." This mention does not make sense in the section dedicated to inorganic materials.

1. A) The reviewer request is correct, but we cannot omit this data as the authors reported it.

 

L382 – C. zeylanicum is in bold and lacks italics.

1. A) Corrected the mistake.

 

L387-396 – The entire paragraph about food does not make any sense to be included in an article focusing on cultural heritage.

1. A) We agree with the reviewer, but we would like to stress the use of the mixture of Essential oils even making some example on food, since few articles of EOs mix on cultural heritage are till now published.

 

L412 – "...referred to..." is duplicated.

1. A) Corrected the mistake.

 

Table 3 and 4 – Some information is missing in these tables, e.g., Stachybotrys chartarum, considered one of the top 10 most dangerous fungi, has been identified in heritage sites.

 

Please review and address these issues accordingly.

1. A) We corrected tables as suggested.

 

Comments on the Quality of English Language

There are still some minor writing errors that need to be corrected, such as:

 

L36-37 - "In fact, they undergoes to different deterioration processes..." refers to cultural heritage, so it would be more appropriate to say "these assets" or "these materials" or something similar.

1. A) Corrected the errors.

 

 

L38 - "such as micro/macro-organisms (biodeterioration), or by physical and chemical agents..." It should be "and" instead of "or" to indicate that both micro/macro-organisms and physical and chemical agents can contribute to deterioration (in a synergistic manner).

 

1. A) Corrected the minor error.

 

 

This review should be applied throughout the entire text.

1. A) Revised english.

Author Response File: Author Response.docx