Evidence for some antimicrobial properties of English churchyard lichens
This article has been Reviewed by the following groups
Discuss this preprint
Start a discussion What are Sciety discussions?Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
The emergence of multidrug-resistant bacteria has driven the need for novel antibiotics. Our investigations have focussed on lichens as they naturally produce a wide range of unique and very effective defence chemicals. The aim of this study was to evaluate some of the antimicrobial properties of ten common British churchyard lichens. The lichen material was sampled from ten species, namely Caloplaca flavescens , Diploicia canescens , Cladonia fimbriata , Psilolechia lucida , Lecanora campestris subsp. Campestris , Lecanora sulphurea, Pertusaria amara f.amara , Lepraria incana , Porpidia tuberculosa and Xanthoria calcicola . Crude acetone extracts of these lichens were tested against six bacteria ( Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonela typhimurium, Listeria monocytogenes and Lactobacillus acidophilus ) and two fungi ( Trichophyton interdigitale and Aspergillus flavus ) by the disc-diffusion susceptibility test method. Extracts of Diploicia canescens, Psilolechia lucida, Lecanora sulphurea, Pertusaria amara and Lepraria incana showed clear inhibition of the Gram-positive bacteria tested ( S. aureus, L. monocytogenes, L. plantarum ). Diploicia canescens, Pertusaria amara and Lepraria incana extracts also inhibited the dermatophyte fungi tested. The Lepraria incana sample tested here was the only extract that showed activity against any of the Gram-negative bacteria tested; it showed inhibition of Pseudomnas aeruginosa . Overall, our results showed that crude extracts of Diploicia canescens and Pertusaria amara had the most potent antimicrobial activity of all the extracts tested. Our results are in general agreement with published findings elsewhere. The activity of the Porpidia tuberculosa margin sample being different from that of the main colony material was an interesting and new finding reported here for the first time.
Article activity feed
-
-
This study would be a valuable contribution to the existing literature. This is a study that would be of interest to the field and community. After two rounds of review, I'm pleased to accept this manuscript. Congratulations and thank you for choosing Access Microbiology for publishing your work.
-
-
-
The work presented is clear and the arguments well formed. This study would be a valuable contribution to the existing literature. This is a study that would be of interest to the field and community. A reviewer from your initial round of review evaluated your revised manuscript and agrees that you have addressed the reviewer comments and the manuscript has been improved. A few minor text issues and typos were detected in your revised manuscript, and I would like to give you the opportunity to address those in your manuscript. Once these have been addressed, please resubmit your manuscript.
-
Comments to Author
The authors have properly addressed the reviewer's comments by adding information on the relevance of the microbial species tested, expanding the discussion and consolidating the style of all sections and especially of the results section. This manuscript will be useful as a reference to researchers looking into antimicrobial activities of lichen secondary metabolites. See below minor amendements The last four sentences of the abstract add a necessary summmary of results and conclusions but have to be re-written in a well constructed style Line 20: Delete although? and Line 23 however instead of although? trying to make sense of the sentence Line 30: I am not sure antimicrobiotics is a common term, I would say antimicrobials Line 38: antimicrobial resistance without capitals Line 69: avoid brackets, …
Comments to Author
The authors have properly addressed the reviewer's comments by adding information on the relevance of the microbial species tested, expanding the discussion and consolidating the style of all sections and especially of the results section. This manuscript will be useful as a reference to researchers looking into antimicrobial activities of lichen secondary metabolites. See below minor amendements The last four sentences of the abstract add a necessary summmary of results and conclusions but have to be re-written in a well constructed style Line 20: Delete although? and Line 23 however instead of although? trying to make sense of the sentence Line 30: I am not sure antimicrobiotics is a common term, I would say antimicrobials Line 38: antimicrobial resistance without capitals Line 69: avoid brackets, ..., thus etc Line 77: aspergillosis doesn't need capital Line 107: mush - typo Line 128: substitute the link with a reference Line 157: this has been correctly moved to the methods section Line 167: this section should remain in the Results Line 247: delete capitals in positive and negative Line 283: I do not think this is an appropriate summary of the main drivers of AMR - see the WHO https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance#:~:text=The%20main%20drivers%20of%20antimicrobial,access%20to%20quality%2C%20affordable%20medicines%2C Line 312 - 314 and throughout the text: avoid the use of brackets, just write sentences as subordinate clauses Line 314: define the MRSA acronym Line 343: allowed us to test whether the prothallus margins etc - I wouldn't phrase it as a question Line 362-363 avoid brackets Line 400: avoid brackets Line 410: RecA and LexA Line 413: rephrase as "could interfere with the SOS response and reduce the transmission of antimicrobial resistance genes" or alternatively "decrease the development of antimicrobial resistance " Line 416: against not in italics Line 417: do not phrase as a question Line 436: future work rather than future steps
Please rate the manuscript for methodological rigour
Good
Please rate the quality of the presentation and structure of the manuscript
Good
To what extent are the conclusions supported by the data?
Partially support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is there a potential financial or other conflict of interest between yourself and the author(s)?
No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?
No: Does not involve animal or human work
-
Comments to Author
The authors evaluated the antimicrobial properties of common English lichens, in a Buckinghamshire churchyard. In spite of the scientific value of the subject, it lacks more detailed information about the antibacterial action of English churchyard lichens. I have several comments listed below. In my opinion, the research needs more data proving this property other than disc diffusion method. IN ABSTRACT, Add a broad conclusion in a well constructed writing style. Moreover, what is the evidence for inhibition of bacteria? LINE 3: Add at the end of the introduction section. LINE 4: Not aim. LINE 7: The authors should not add tittles in the introduction section. LINE 21: The authors must talk about the problem they deal with. LINE 43: Where is the clinical importance of the investigated bacteria and …
Comments to Author
The authors evaluated the antimicrobial properties of common English lichens, in a Buckinghamshire churchyard. In spite of the scientific value of the subject, it lacks more detailed information about the antibacterial action of English churchyard lichens. I have several comments listed below. In my opinion, the research needs more data proving this property other than disc diffusion method. IN ABSTRACT, Add a broad conclusion in a well constructed writing style. Moreover, what is the evidence for inhibition of bacteria? LINE 3: Add at the end of the introduction section. LINE 4: Not aim. LINE 7: The authors should not add tittles in the introduction section. LINE 21: The authors must talk about the problem they deal with. LINE 43: Where is the clinical importance of the investigated bacteria and fungi LINE 64: This is not materials. LINE 78: Where is the method used? Please, add in details. LINE 88: Were expected?????? LINE 215: Where is the statistical analysis? LINE 250: Add in footnotes of the table Table 4: What is the relevance for 1,2,3. Moreover, there are empty cells. LINE 258: Not detail all results. Focus only on the most important findings. LINE 266: What is the significance relevance for these results? LINE 296: The same comments for bacteria must be considered here. LINE 316: Not add titles. LINE 439: What are the possible modes of actions for these extracts on the bacterial and fungal isolates? LINE 456: All discussion needs interpretation.
Please rate the manuscript for methodological rigour
Good
Please rate the quality of the presentation and structure of the manuscript
Good
To what extent are the conclusions supported by the data?
Partially support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is there a potential financial or other conflict of interest between yourself and the author(s)?
No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?
No: The manuscript does not involve any human and/or animal work.
-
The reviewers have raised concerns about the formatting of the manuscript and made suggestions for improvement in this area. There are also points raised about the experimental work, for example if disk diffusion assays are sufficient to support your claims and the choice of media used. Please address these points in writing in your revision. Further experimental work is not required, but should you choose to do that and will need more time, please let us know. This study would be a valuable contribution to the existing literature. This is a study that would be of interest to the field and community. The reviewers have highlighted minor concerns with the work presented. Please ensure that you address their comments.
-
Comments to Author
I enjoyed reading this manuscript and I found it interesting as it highlights lichens as a potential source of natural products with antimicrobial activity. The authors aimed at assessing the antimicrobial activities of secondary metabolites produced by churchyard lichens . They successfully extracted chemicals from ten species and tested them against six bacterial and two fungal species via disk diffusion test. The authors were able to draw conclusions with regards to the antimicrobial activities of the lichen extracts, although more detail is needed as to why the metabolites may be active against specific pathogens. The choice of media for antimicrobial susceptibility testing also needs to be justified. Finally, the manuscript needs formatting to bring it in line with scientific publishing. Here are …
Comments to Author
I enjoyed reading this manuscript and I found it interesting as it highlights lichens as a potential source of natural products with antimicrobial activity. The authors aimed at assessing the antimicrobial activities of secondary metabolites produced by churchyard lichens . They successfully extracted chemicals from ten species and tested them against six bacterial and two fungal species via disk diffusion test. The authors were able to draw conclusions with regards to the antimicrobial activities of the lichen extracts, although more detail is needed as to why the metabolites may be active against specific pathogens. The choice of media for antimicrobial susceptibility testing also needs to be justified. Finally, the manuscript needs formatting to bring it in line with scientific publishing. Here are some suggestions which in my opinion would improve the manuscript. The first methods paragraph should not be included, as it does not describe a method. The authors could briefly comment on the choice of using acetone as the most appropriate solvent in the results section, if they wished. The second Methods paragraph is also redundant and non-informative, as later paragraphs describe in depth the antimicrobial susceptibility test procedure that they followed. The choice of growth media for the pathogens should also be justified, as Mueller-Hinton agar is most commonly used for disk diffusion tests for bacteria. The choice of bacterial and fungal species tested should also be made more explicit, with reference to their pathogenicity. The use of sterile technique can be given for granted for this kind of study and doesn't need to be specified. Standardising the stock extract solutions to the same concentration or the load per disc would have been helpful for the interpretation of results. The authors should point out why and where this was not possible. The first results paragraph should be moved to the Methods section. In Table 4 and 5, it would be helpful to include the average with standard deviation of the three triplicate experiments, rather than listing them individually. The full description of the table should be moved on top of it and the meaning of the notation "NT" should be included. The introduction and discussion sections should not have subtitles, and the aims should be moved at the end of the introduction. Throughout the manuscript there are formatting inconsistencies which need to be corrected. Antibiotics like chloramphenicol and the names of metabolites and acids do not require the capital letter and units of measure should be separated with a spacing from the number. Line 431, typo. Line 356, delete "(apparently!)". The authors explained in depth with references to the literature why lichens are hypothesised as a source of novel antimicrobials. Some of the tested lichen species did indeed show antimicrobial activity, while others, in disagreement with previous literature, did not. The authors discuss which lichen metabolites could be responsible for the antimicrobial activity and why some lichen extracts did not show the expected activity. I would suggest that the authors include more detail as to why the metabolites have antimicrobial activity and which are the supposed mechanisms of inhibition of pathogens growth. It would also be helpful to comment on why some lichen extracts have more activity on Gram positive species rather than Gram negative and why A. flavus appears to be more resistant than T. interdigitale. Interestingly, the authors also state that they were able to test whether different parts of the same lichen contained different amounts of metabolites. However, the details on sampling which led to the possibility of testing this hypothesis should have been described in the methods section. I think the discussion of limitations of the study raises a compelling and important point.
Please rate the manuscript for methodological rigour
Satisfactory
Please rate the quality of the presentation and structure of the manuscript
Poor
To what extent are the conclusions supported by the data?
Partially support
Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?
No
Is there a potential financial or other conflict of interest between yourself and the author(s)?
No
If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?
Yes
-