Lactobacillus acidophilus in Aquaculture: A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper reviews current research on the use of Lactobacillus acidophilus in aquaculture. The authors analyze this probiotic organism's effects on growth, digestive morphology, microbial community, immune system, and resistance to pathogens within aquaculture. It should be noted that this paper is not entirely aligned with the special issue “The Role of Microorganisms in Waste Treatment,” although it addresses a similar area.

The manuscript is well-structured; each topic covered is supported by numerous examples from published research. The references cited include both seminal and recent publications from the last five years, demonstrating the review's relevance. Of particular note is the balanced approach of the authors, who consider not only positive, but also neutral or negative results of L. acidophilus. This approach provides an objective and comprehensive coverage of the issues. In addition, the authors outline promising areas of research in this field (e.g., selection of optimal dosage, effect of co-administration with other probiotic microorganisms), which increases the practical significance of the review. Despite the abundance of general reviews on the use of probiotics, the present work, focused on a specific species, has high scientific value. It allows for the consolidation of specific scientific data, the determination of L. acidophilus's efficacy, and the assessment of its prospects for application in aquaculture.

Despite the completeness of the presented information on the use of L. acidophilus, the authors, it is felt, do not adequately address the molecular and cellular mechanisms of action of probiotics.

Specific comments:

- The genus Lactobacillus is one of many taxa of lactic acid bacteria (LAB) with probiotic properties. Therefore, it is recommended that the authors provide a brief overview of other probiotic LAB species and their potential applications in aquaculture in the introduction.
    
- It should be emphasized that the species L. acidophilus is characterized by significant heterogeneity across various biochemical and genetic markers. This leads to potentially significant differences in functional properties and probiotic efficacy between individual strains. In this regard, it is crucial to include the names of specific L. acidophilus strains in the text of the manuscript and tables where applicable.
    
- For example, in Section 4, which discusses the stimulatory effects of probiotics on the host immune system through specific and nonspecific components (lines 138-142), it is useful to briefly mention the key role of pattern recognition receptors (PRRs), which preferentially mediate the stimulation of the nonspecific immune response.
    
- Similarly, in Section 5, which summarizes the improvement in host resistance to pathogens (lines 172-175), the authors should further highlight the known mechanisms by which probiotics act on pathogenic and opportunistic microorganisms, such as competitive exclusion, competition for adhesion sites, inhibition of quorum sensing, and competition for nutrients (including production of siderophores).
    
- The inclusion of such brief yet precise clarifications regarding the mechanisms of action in each relevant section (1-5) will greatly enhance the informative value of the manuscript, especially for readers who are not specialized experts in the field.

Author Response

This paper reviews current research on the use of Lactobacillus acidophilus in aquaculture. The authors analyze this probiotic organism's effects on growth, digestive morphology, microbial community, immune system, and resistance to pathogens within aquaculture. It should be noted that this paper is not entirely aligned with the special issue “The Role of Microorganisms in Waste Treatment,” although it addresses a similar area.

The manuscript is well-structured; each topic covered is supported by numerous examples from published research. The references cited include both seminal and recent publications from the last five years, demonstrating the review's relevance. Of particular note is the balanced approach of the authors, who consider not only positive, but also neutral or negative results of L. acidophilus. This approach provides an objective and comprehensive coverage of the issues. In addition, the authors outline promising areas of research in this field (e.g., selection of optimal dosage, effect of co-administration with other probiotic microorganisms), which increases the practical significance of the review. Despite the abundance of general reviews on the use of probiotics, the present work, focused on a specific species, has high scientific value. It allows for the consolidation of specific scientific data, the determination of L. acidophilus's efficacy, and the assessment of its prospects for application in aquaculture.

Despite the completeness of the presented information on the use of L. acidophilus, the authors, it is felt, do not adequately address the molecular and cellular mechanisms of action of probiotics.

Specific comments:

- The genus Lactobacillus is one of many taxa of lactic acid bacteria (LAB) with probiotic properties. Therefore, it is recommended that the authors provide a brief overview of other probiotic LAB species and their potential applications in aquaculture in the introduction.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have added several common types of lactic acid bacteria (Lactobacillus plantarum and Lactobacillus bulgaricus), and have provided references (References 3, 4, 9 and 10). In our brief introduction of the functions of these additional bacterial strains, we have ensured they relate to the primary focus of this study (Lactobacillus acidophilus). However, expanding on the roles of other bacterial species in aquaculture would deviate from our research topic. So we did not add any more information. (line 30-33)

 

- It should be emphasized that the species L. acidophilus is characterized by significant heterogeneity across various biochemical and genetic markers. This leads to potentially significant differences in functional properties and probiotic efficacy between individual strains. In this regard, it is crucial to include the names of specific L. acidophilus strains in the text of the manuscript and tables where applicable.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 121, line 219, line 254)

 

- For example, in Section 4, which discusses the stimulatory effects of probiotics on the host immune system through specific and nonspecific components (lines 138-142), it is useful to briefly mention the key role of pattern recognition receptors (PRRs), which preferentially mediate the stimulation of the nonspecific immune response.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 155-163).

 

- Similarly, in Section 5, which summarizes the improvement in host resistance to pathogens (lines 172-175), the authors should further highlight the known mechanisms by which probiotics act on pathogenic and opportunistic microorganisms, such as competitive exclusion, competition for adhesion sites, inhibition of quorum sensing, and competition for nutrients (including production of siderophores).

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 195-215)

 

- The inclusion of such brief yet precise clarifications regarding the mechanisms of action in each relevant section (1-5) will greatly enhance the informative value of the manuscript, especially for readers who are not specialized experts in the field.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 47-48, line 101-105, line 119-125, line 155-163, line 219-224)

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Author,

You made a good effort in this review. I have few suggestions and questions. Please address them carefully.

Beast wishes.

• Please include a critical discussion on the limitations and inconsistent findings of L. acidophilus use in aquaculture.
• Add a section comparing the effects of different probiotic strains (example: Lactobacillus plantarum etc.), not only L. acidophilus.
• The current review summarizes positive studies only; consider discussing studies that showed no effect or negative outcomes.
• Explain the molecular mechanisms behind immune modulation and growth promotion in more detail.
• Remove repeated content—several sentences and data are repeated in both text and tables.
• Add a visual summary figure to show how L. acidophilus works in aquatic systems.
• Improve the conclusion by suggesting specific future research directions, not general statements.
• Include more recent studies from the last 2–3 years to strengthen the review.
• Please cite more recent probiotic application studies in marine fish species (probiotics (Lactobacillus) sourced from fish and applied on fish farms etc.).
• Please improve English grammar and sentence clarity throughout the manuscript.

Comments on the Quality of English Language

English Proofreading is recommended

Author Response

You made a good effort in this review. I have few suggestions and questions. Please address them carefully.

Beast wishes.

Please include a critical discussion on the limitations and inconsistent findings of L. acidophilus use in aquaculture.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 85-95)

 

Add a section comparing the effects of different probiotic strains (example: Lactobacillus plantarum etc.), not only L. acidophilus.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. Currently, while there are numerous studies comparing Lactobacillus acidophilus with other Lactobacillus species (such as https://doi.org/10.1128/AEM.02675-08,  https://doi.org/10.1016/j.ijantimicag.2016.05.014, https://doi.org/10.1016/j.foodchem.2020.127922, https://doi.org/10.1111/j.1574-695X.2010.00662.x, https://doi.org/10.1080/08905436.2012.724037, https://doi.org/10.1590/S0004-2803.201800000-87, https://doi.org/10.3389/fnut.2022.833906, DOI: 10.4103/ijabmr.IJABMR_329_16, https://doi.org/10.1016/j.lwt.2022.114104), very few focus on fish as the research subject (DOI: 10.22059/ijvm.2018.235444.1004816, https://doi.org/10.1038/s41598-020-62655-y), which is insufficient to warrant a dedicated section. Consequently, these references have been included in the introduction. Most research subjects are plants, humans, and mice; therefore, adding a section to compare the functions of Lactobacillus acidophilus with other lactobacilli would be inappropriate. The central theme of this study is the role of Lactobacillus acidophilus in aquaculture, so only a brief overview of other lactobacilli is provided in the introduction. Thank you once again for your suggestions. (line 30-33)

 

The current review summarizes positive studies only; consider discussing studies that showed no effect or negative outcomes.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 85-95)

 

Explain the molecular mechanisms behind immune modulation and growth promotion in more detail.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have already supplemented the relevant information. (line 119-125, line 155-163, line 195-215, line 219-224)

 

Remove repeated content—several sentences and data are repeated in both text and tables.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have revised the Table.

 

Add a visual summary figure to show how L. acidophilus works in aquatic systems.

 Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We added a visual summary figure. (line 292)

 

Improve the conclusion by suggesting specific future research directions, not general statements.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We put forward some specific suggestions. (line 294-303)

 

Include more recent studies from the last 2–3 years to strengthen the review.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have added 18 references, 7 of which were published between 2023 and 2025. (reference 9, 10, 20, 39, 43, 54, 64)

 

Please cite more recent probiotic application studies in marine fish species (probiotics (Lactobacillus) sourced from fish and applied on fish farms etc.).

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We have added 6 references, including fish and shrimp. (reference 22, 31, 32, 42, 46, 48)

 

Please improve English grammar and sentence clarity throughout the manuscript.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We asked colleagues whose native language is English to perform a comprehensive grammar check on the text.

Reviewer 3 Report

Comments and Suggestions for Authors

Comments on the manuscript with ID (microbiolres-3735911-peer-review-v1)

There are a lot of comments in the reference section. I highlighted these comments and used track changes to allow the authors to revise. My advice to the authors is to cite only the papers presented in the PubMed database and ignore others. I found that the authors had multiple non-indexed Chinese references.

Tables: You should add a list of abbreviations below each table.

You should abbreviate the Latin names after their first appearance in the text.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

 The English could be improved to more clearly express the research.

Author Response

Comments on the manuscript with ID (microbiolres-3735911-peer-review-v1)

There are a lot of comments in the reference section. I highlighted these comments and used track changes to allow the authors to revise. My advice to the authors is to cite only the papers presented in the PubMed database and ignore others. I found that the authors had multiple non-indexed Chinese references.

Answer: Thank you for the reviewers' suggestions. Our standard for citing references includes publicly published papers. Even if the journal is a regular publication, these studies are of great importance to this research. At the same time, we have modified the format of all references. Thank you once again for your comments.

 

Tables: You should add a list of abbreviations below each table.

Answer: Thank you for the reviewers' suggestions. We have changed the content of the table.

 

You should abbreviate the Latin names after their first appearance in the text.

Answer: Thank you for the reviewers' suggestions. These recommendations have significantly improved the manuscript. We conducted a full text check and made corrections.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors appropriately responded to the points and questions raised by the reviewer