Exploring the Influence of Light Wavelength Ranges and Nutrients Reduced Availability’s Impacts on Polyhydroxyalkanoates Accumulation in Purple Phototrophic Bacteria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title: Exploring the influence of light wavelength ranges and nutrients
reduced availability’s impacts on polyhydroxyalkanoates accumulation in
purple phototrophic bacteria.
Manuscript ID: fermentation-3577238.
The study presents an innovative approach by integrating continuous light wavelength exposure with a two-stage nutrient reduction system to enhance PHA biosynthesis. This approach is commendable for its originality and relevance to the field of sustainable wastewater treatment. The manuscript effectively highlights the dominant role of light type in influencing PHA production, a crucial parameter often overlooked in similar studies. This focused approach is highly commendable. The paper is well-structured, providing a concise yet comprehensive overview of the research. The logical flow from objectives to findings ensures clarity and coherence, which is essential for engaging the reader. I greatly appreciate the research team and I recommend this paper for acceptance in FERMENTATION journal

Author Response

Reviewer Comment: The study presents an innovative approach by integrating continuous light wavelength exposure with a two-stage nutrient reduction system to enhance PHA biosynthesis. This approach is commendable for its originality and relevance to the field of sustainable wastewater treatment. The manuscript effectively highlights the dominant role of light type in influencing PHA production, a crucial parameter often overlooked in similar studies. This focused approach is highly commendable. The paper is well-structured, providing a concise yet comprehensive overview of the research. The logical flow from objectives to findings ensures clarity and coherence, which is essential for engaging the reader. I greatly appreciate the research team and I recommend this paper for acceptance in FERMENTATION journal

Response: We greatly appreciate the positive feedback and recommendation of the reviewer. Thank you.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,

 

I reviewed your intriguing manuscript, which describes the production of PHA by phototrophic purple bacteria from fuel synthesis wastewater. The effect of nitrogen and phosphate limitation on nutrient consumption and biomass and PHA formation was studied, as well as the impact of different illumination regimes. It was shown that especially the light supply plays a decisive role for the biotechnological process.

The work is scientifically sound, and contributes to our understanding of the coupling of waste water treatment and bio-production of value-added products. Some aspects should be addressed on order to further improve your submission:

1. Line 81, 88, 88, etc.: genus and species names need to be italicized.
2. Check your text again carefully: lines 116-124 is a pure repletion of previous text parts, the same goes for the entire section 2.2 (line 200-210).
3. Line 222 etc.: unit “mg-COD/L∙d” should be “mg COD / (L∙d)”
4. Figure 2: this is a fed-batch profile as visible by the substrate increase at day 7; hence, there you need to insert an arrow shown that a substrate feeding pulse was supplied. This arrow needs to be explained in the figure legend.

Author Response

Comments 1: Line 81, 88, 88, etc.: genus and species names need to be italicized.

Response 1: Thank you for pointing out this point. We agree with the reviewer. All occurrences of genus and species names such as Rhodopseudomonas, Rhodopseudomonas palustris, and Rhodobacter sphaeroides have been italicized throughout the main text and the reference section. [Revisions made on lines 81, 82, 84, 88 throughout the introduction section of the manuscript and on lines 600, 607, 611, 636 and 641 in the reference section of the manuscript.]

Comments 2: Check your text again carefully: lines 116-124 is a pure repletion of previous text parts, the same goes for the entire section 2.2 (line 200-210).

Response 2: Thank you for pointing this out. We have removed the repeated paragraphs in lines 116–124 from the introduction and deleted the duplicate Section 2.2 in lines 200–210. [Revisions made in Page 3, Lines 116–124, and on Page 5 and 7, Lines 200–210.]

Comments 3: Line 222 etc.: unit “mg-COD/L∙d” should be “mg COD / (L∙d)”

Response 3: We appreciate this formatting correction. All instances of “mg-COD/L∙d” have been corrected to “mg COD / (L∙d)” throughout the manuscript for consistency. [Revisions made in lines 222, 223, 224, and 225.]

Comments 4: Figure 2: this is a fed-batch profile as visible by the substrate increase at day 7; hence, there you need to insert an arrow shown that a substrate feeding pulse was supplied. This arrow needs to be explained in the figure legend.

Response 4: Thank you for this helpful observation. We have added an arrow to each graph in Figure 2 indicating the beginning of the second stage on Day 7 and updated the figure caption accordingly. [Revised figure and caption are included in the updated manuscript on Page 7, Figure 2 and its caption in lines 279-280.]