Lactic Acid Bacteria: Food Safety and Human Health Applications

Round 1

Reviewer 1 Report

Lactic Acid Bacteria: Food Safety and Human Health Applications

The authors present the review of properties of lactic acid bacteria (LAB), their recent classification and perspectives on industrial applications with a focus on food safety and desirable benefits to human health. In researchers opinion regular consumption of fermented dairy products, meat and vegetable origins helps maintain a healthy microbiota and prevent gut dysbiosis-linked diseases. The lactic acid bacteria (LAB) present in food enhance the digestibility of proteins, moderate the release of fatty acids, and support human health through inhabiting the gastrointestinal tract. The authors suggest the bio-preservation as one of the many attributes derived from lactic bacteria under the scope of food safety (production of bacteriocins that are able to inhibit the growth of spoilage and pathogenic bacteria in foods).  

The title of publication reflect its content. The paper written concisely and clearly. The authors are using standard and understandable professional names. The summary clearly state the objective of the study. The review  support stated conclusions with reference to the current situation with COVID 19. The results (figures and tables) were expressed in the most appropriate form with reference to the text. They are written according to the  instructions. The references are up-to-date. Lack of portion of the paper which are unnecessary or need to be extended.

Nevertheless, I will give some comments:

• The introduction is short, written well and clearly.
• Line 80: The major genera is shown on Figure 1, which is not very clear, especially in the overview tree of phylogroups of Lactobacillaceae and Leuconostocaceae. Please use italics in the Figure 1 for Latin names.
• Lines 199: In Table 3 should be: “Lactococcus lactis lactis, Lactococcus lactis ssp. cremoris, Lactobacillus delbueckii ssp. bulgaricus”; ssp. and sp. without italica.
• Lines 214: Please use Latin names consistently in all text, e.g. Lactobacillus delbueckii bulgaricus.
• Lines 255-609: This part of the text ( History of Probiotics) appears to be too long, but, in my opinion, the topic is worth the reminder in times of recent events.

The overall quality of this paper is good.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

General comments.

The review Lactic Acid Bacteria: Food Safety and Human Health Applications is relevant topic in dairy industry. The author explains the beneficial effect of these LAB. However, I consider they need to reorganize some sections and prepare new figures to give another perspective to readers.

I have started reading this review with great expectations, but they were delivering very generic information that can be found in many textbooks and in a greater number of published reviews. For example, the introduction and definition of Lactic Acid Bacteria is very general and extensive, I recommend to summarized.

The manuscript looks like was made by two different authors. For example, many times they use the term micro flora, which is no longer used, in other sections they use microbiota. That is the correct term. Please, could you change microflora by microbiota?

In the genetic context. Could you address the new generation to identify the LAB in dairy products, as well the genomic and metagenomic reports? For example, Alvarez-Sieiro et al. (2016) they describe the bacteriocins family in LAB, using in silico publicly available LAB genomes.

The LAB names need to be homogenized using “Lb.” or “L.” to indicate the genus. In table 1  some species are “Lb.” and in table 3 the same species are abbreviated “L.” casei.  

The sections 2.3. Probiotics and Human Health and 2.4. Beneficial Effects of Probiotic LAB on Human Health, look repetitive. Could you combine and summarize the sections?

Also, the authors have essential information to prepare new figures. Because the propose of the review is to provide information from another perspective. In the same topic, all the figures have low resolution.

About of 2.5 Health Benefits of Probiotics in Some Disease Conditions section, I really enjoyed the section. The author explains a detail the lactose intolerance (2.5.1. Lactose Intolerance), however I consider that the sections 2.5.2 to 2.5.6 need to be more extensive and explain more a detail the mechanism to illustrate the beneficial human effect.

P1 L36-37. Could you rewrite “that impart food with desirable flavors”

P2 L84-89. Could you address the re-classification of some LAB? (Zheng et al., Int. J. Syst. Evol. Microbiol. 2020;70:2782–2858, DOI 10.1099/ijsem.0.004107).

P3 Figure 1. A and B don’t show essential differences. I recommend include just one figure.

P4 L100-101. Could you include the reference?

P4 L100-101. Do you think that the interaction is specific with enteric bacteria? Or can be with another LAB?

P4 L115. Could you include the reference?

P4 L124-143. The author focuses in bacteriocins from LAB, however other antibacterial proteins like a lysin, endolysin, peptidoglycan hydrolases, etc., are produce from LAB. Could you address more about of these proteins?

Table 1. Lysostaphin is not a real protease. As you separate the bacteriocins classification. Could you give the characteristic property about of Class IIIa and IIIb. Change “helveticas” by “helveticus”

P9 L165. Change “microbial flora” by “microbiota”

P10 L199. Table 3 change “Cremoris” by “cremoris” and “delbueckii” by “delbrueckii”

P11 L209. Bacteriophage contamination is a dairy industry issue. Could you address about of bacteriophage tolerance?

P11 L212. Table 4, in starter bacteria column… could you specify “lactic acid bacteria” and autolytic lactic acid bacteria”?

P13 L298. Could you address about of the genetic mechanism of probiotics? Wesley Morovic ,

and Charles R. Budinoff 2020.

P13 L299-300. The authors say, “Many schools” and just added one reference (73)

L486. I consider that this is an interesting topic. Could you address the effect of LAB over diabetes and obesity? Include mechanism of action.

L487 and 490. Change “flora” by “microbiota”

L509-5011. The authors say “many research” but they add only one reference (73). Also, could you add research references?

L611. I don’t share the idea to generalized that the LAB are safe… some LAB species have been reported as pathogenic

L626-628. This paragraph is not clear.

L629-632. I think it is very adventurous to mention this effect. To conclude, need to be additional clinical investigation and studies.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript entitled "Lactic acid bacteria: Food Safety and Human Health Application" by Ayivi et al. tries to present the most recent information regarding LAB as probiotics. Unfortunately, the manuscript should be improved/changed in many parts. Firstly, the title does not correspond to the manuscript as food safety issues of probiotics are not properly discussed. In a review with this title safety assessment of probiotics, risk of probiotics’ infections, harmful gene transfer, antibiotic resistance, virulence factors should be mentioned and this is not the case for the present manuscript. Consequently, the safety part is not covered. Human health applications are presented better but still very important health applications of LAB probiotics are still missing (e.g. allergy, urogenital infections, gut-brain axis). The fact that the authors promote in their manuscript the antiviral activity of LAB (due to the emerged interest of the scientific community on viruses) is very interesting. Still, the parts concerning antiviral probiotic effects have already been published in other articles and the manuscript does not provide any updated information (e.g. already published the Figure 7 and the mechanisms below, information of Table 6 also published in other reviews). Except the previous comments, the structure of the manuscript is quite strange with a lot of repetitive information (see specific comments below). The authors should think what they really want to present in this review and focus on it.

Specific comments:

1. Line 48: “Probiotics work in tandem with LAB….”, this is a serious mistake…Probiotics are the lactic acid bacteria (at least in most cases). Also in Line 18 (“Probiotics and LAB….”)
2. Paragraph 1.1. for taxonomy: please re-write, Lactobacillus group/genus consists of Lactococcus, Enteroccocus and Bifidobacterium species? Please correct
3. Paragraph 1.2. for niche and habitat of LAB: What about focusing on sources of LAB (fermented foods, intestinal tract of healthy subjects). Data for probiotics against pathogens have no sense here
4. Paragraphs 1.4, 1.5 and 1.6 can be merged, along with Tables 3 and 4. LAB in fermented foods can be presented better
5. Paragraph 1.7: Why the authors mention only this species? No explanation is given, also many details for nomenclature that are not essential.
6. Paragraph 2.1.: All strains of one species are probiotics? Strain-specificity should be discusssed
7. Lines 325-342: An updated review can be found
8. Paragraphs 2.3 and 2.4 have almost the same title and content, Figure 2 is almost the same with Figure 4
9. Lines 405-429: Some parts have been already discussed in the previous lines of the manuscript, repetitions throughout the text
10. Lines 445-474: Lactose intolerance with a lot of details, this part can be shortened
11. Antiviral activity: The interesting part of the manuscript but lack of updated information

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I know that the authors are limited to the number of pages, however I consider that they can summarize some sections in order to improve the food safety and health benefits sections, because the review title is: Food Safety and Human Health Applications.

Again, I consider that the authors need to reduce the probiotics sections in order to give more information about the other proteins with antibacterial activity, to improve the food safety section in dairy products. As well, the author describes the bacteriocin classification to detail, I suggest reducing the bacteriocins section and address other proteins or peptides, from LAB and dairy products, with antibacterial activity.

Human Health applications, I consider amplify this section and address Diabetes and Obesity, Acute Diarrheal Disease and Cardiovascular diseases.

Minor points.

-Figure 1, improve the quality and remade the figure with the new classification.
-Check all the Lb. abbreviations
-L393 delete LAB

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript entitled "Lactic acid bacteria: Food Safety and Human Health Application" by Ayivi et al. tries to present the most recent information regarding LAB as probiotics. The manuscript was improved in many aspects. The structure of the manuscript is better than before and a lot of repetitive information was excluded. Still, some parts can be improved more (see specific comments below). Please check throughout the text so as to use the abbreviation LAB, in many cases the authors use the term “lactic acid bacteria” and not its abbreviation.

Specific comments:

1. Lines 19-20: Rephrase the last sentence of the abstract
2. Lines 24-26: Correct grammatical errors, i.e. “LAB play” and not “LAB plays” and others
3. Line 61: Italics for the genus Lactobacillus
4. Lines 61-66: Please correct, the new genera are Lactobacillus, Paralactobacillus and the 23 novel genera. It is not clear. In addition, again problems with the Figure 1, it is not clear.
5. Correct ClassIib and ClassIic with ClassIIb and ClassIIc, respectively, in Table 1
6. Line 160 and line 163: Change the word “Class” with the word “Group”
7. Please shorten Paragraph 2.3. The authors have just left the text as it was before (in two separate paragraphs) and they have information repetition in this part, e.g. Lines 355-357 are the same with Lines 399-423 in more details, also Lines 393-398 have been already mentioned before in the text. Please change it
8. My comment for important health benefits of probiotics (e.g. allergy, urogenital infections, gut-brain axis) that are missing from the manuscript was not taken into account due to limited number of pages. I am not totally ok with this as you can decrease words/pages in other parts in order to ameliorate your manuscript
9. Mechanisms of probiotic action on viruses: What about antiviral properties of bacteriocins, this is quite important. If you have limitations you can exclude all the details you have for Figure 5 as it is already published. In this way, you have more words/pages to write about reported antiviral bacteriocins.

Author Response

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Author Response File: Author Response.docx