Isolation of γ-Aminobutyric Acid (GABA)-Producing Lactic Acid Bacteria with Anti-Inflammatory Effects from Fermented Foods in Korea

Round 1

Reviewer 1 Report

The authors of the present study isolated lactic acid bacteria from various Korean fermented foods and evaluated the anti-inflammatory effects of GABA-producing strains on macrophages to determine their potential use as probiotics. They selected four L. brevis strains exhibiting the ability to convert glutamate, into GABA.  All these strains exhibited anti-inflammatory activity inhibiting NO and iNOS production, and NF-kB activity.

The selected strains, by virtue of their anti-inflammatory activity and the production of GABA, could be used in functional foods to increase neurological stability and to reduce blood pressure.

The paper is interesting and well executed, however, in the Introduction, the assertion that “artificially" synthesized GABA exhibits several side effects, including loss of appetite, constipation, and diarrhea”, seems groundless, no citations are indicated. Why in your opinion GABA obtained “artificially” should have different side effects than GABA obtained by natural fermentation?

Author Response

26 June, 2023

Article ID: Fermentation-2479242

Dear reviewer in fermentation

We are very grateful for the comments of reviewers to improve the quality of the article.

This manuscript has been revised based on the comments in the review.

Thanks for your attentive comments.

Below is a summary of the answers to each comment.

Reviewer 1.

The paper is interesting and well executed, however, in the Introduction, the assertion that “artificially" synthesized GABA exhibits several side effects, including loss of appetite, constipation, and diarrhea”, seems groundless, no citations are indicated. Why in your opinion GABA obtained “artificially” should have different side effects than GABA obtained by natural fermentation?

Reply:

Thank you for your comment.

According to reviewer’s comments, I would like to delete the relevant part and add new content and reference to the introduction part as follows.

 Recent studies have reported that GABA improves plasma growth hormone level, brain protein synthesis, memory, and cognitive ability; lowers blood pressure; and relaxes the nerves [3,4]. Several studies have focused on the mass production of GABA; however, artificially synthesized GABA exhibits several side effects, including loss of appetite, constipation, and diarrhea. Therefore, research is being conducted to increase the natural production of GABA [5]. In addition, GABA produced by microbial fermentation is eco-friendly and safe, so GABA has the potential to provide new products beneficial to health [5]. [Page 1, line 28-29]

5. Saikusa, T.; Okada, T.; Murai, H.; Ohmori, M.; Mori, Y.; Horino, T.; Itou, M.; Onoda, A. The Effect of Defatting with Organic Solvent on Accumulation of 4-Aminobutyric Acid (GABA) in the Rice Germ. Nippon Shokuhin Kagaku Kogaku Kaishi 2001, 48, 196–201, doi:10.3136/NSKKK.48.196.

     5. Dhakal, R.; Bajpai, V.K.; Baek, K.H. Production of gaba (γ - Aminobutyric            acid) by microorganisms: a review. Braz J Microbiol. 2012, 43(4):1230-41.              doi: 10.1590/S1517-83822012000400001. Epub 2012 Jun 1. PMID:                 24031948; PMCID: PMC3769009.

Reviewer 2 Report

Cell viability

After suspending RAW 264.7 cells in DMEM con-122 taining 10% FBS, 100 μL of the cell suspension was added to 96-well plates (Corning, 123 USA), with 1 × 105 cells in each well

 The comment is How the cells (1 × 105) was adjusted

Author Response

26 June, 2023

Article ID: Fermentation-2479242

Dear reviewer in fermentation

We are very grateful for the comments of reviewers to improve the quality of the article.

This manuscript has been revised based on the comments in the review.

Thanks for your attentive comments.

Below is a summary of the answers to each comment.

Reviewer 2.

1. After suspending RAW 264.7 cells in DMEM containing 10% FBS, 100 μL of the cell suspension was added to 96-well plates (Corning, 123 USA), with 1 × 10⁵cells in each well

 The comment is How the cells (1 × 10⁵) was adjusted.

Reply:

Thank you for your comment.

We performed cell counting using a cell counter (EVE plus Automated Cell Counter, NanoEntek) according to the manufacturer's manual and seeded 1x10⁵ cells/well in a 96-well plate.