Review Reports - Mangrove-Derived Microbial Consortia for Sugar Filter Mud Composting and Biofertilizer Production

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Title:

Current title:

Mechanisms and Applications of Mangrove-derived Microbial Enhancement in Sugar Filter Mud Composting: Effects of Bacterial Succession on Compost Maturation and Crop Productivity

The title is informative but very long and dense. It tries to include mechanisms, applications, microbial succession, compost maturation and crop productivity all at once, which makes it hard to read and remember.

Figures and visualisation of results

A major weakness of the current manuscript is that many figures are too small and difficult to read in the document. This is particularly critical for multi-panel figures and micrographs.

2.1. Figure 1 – Microbiome profile of mangrove ecosystems

Figure 1 combines three panels (a–c: bar plots + phylogenetic distribution + heatmap) on a single page.
The axis labels, taxa names and legends are very small, especially in the heatmap (panel c), making it hard to identify genera and abundance trends.

Suggestions

Increase the overall size of Figure 1 and the font size of labels.
Consider splitting into two figures (e.g. taxa composition vs heatmap) if necessary to maintain legibility.

2.2. Figure 2 – Temperature, OM, EC, moisture vs time

Four time-series plots (a–d) are placed together, each occupying a small area. In the current layout, tick labels, units and legend symbols are barely readable.
There are no error bars, so readers cannot assess variability or replication.

Suggestions

Enlarge each panel or group them into two figures (e.g., 2a–b and 2c–d).
Increase font sizes for axes and legends.
If biological replicates exist (which should be clarified), add mean ± SD and indicate statistically significant differences between treatments.

2.3. Figure 3 – Elemental composition

Multi-panel plots again appear very compact; labels “Experimental vs Control” and elemental symbols are small.
The legend in panel (a) with multiple-coloured bands is difficult to interpret at current size.

Suggestions

Increase figure size and label fonts.
Consider simplifying panel (a) or plotting fewer key elements per panel to avoid visual overload.

2.4. Figure 4 – SEM micrographs

Six SEM images (a–f) are placed on one page, each extremely small. The microstructural details, pores and aggregate morphology are almost impossible to see, and the arrow/circle in panel (e) is not clear.

Suggestions

Use fewer, larger SEM images, or split them into separate figures (e.g., control vs inoculated; early vs mature stage).
Ensure scale bars and magnification are clearly visible.
If possible, add quantitative descriptors (e.g., pore size distribution from image analysis) to complement the qualitative SEM description.

2.5. Figure 5 – Heatmap of bacterial succession

The heatmap of dominant genera over time is again very small; genus names on the y-axis and colour scale are difficult to read.

Suggestions

Increase size or split into two panels (e.g., early vs late succession).
Alternatively, replace the heatmap with stacked bar charts at each time point highlighting key genera, which may be easier to interpret.

2.6. Figure 7 – Pot experiment

Photographs of plants (7a,b) are visually informative but low in detail at current size. The bar plot (7c) is also small, and axis labels are not clear.

Suggestions

Enlarge bar plot (7c), use larger fonts, and add error bars + significance letters to clearly show treatment differences.
Ensure high-resolution plant photos in the final version so that growth differences can be visually appreciated.

Materials and Methods – missing details and reproducibility

Overall, the methodology is well structured but some critical information is missing or too vague, which limits reproducibility.

3.1. Composting experiment (Section 2.2)

The text states that 30 L reactors with ~30 kg filter mud were used, a control and a bio-augmented group, with sugarcane bagasse as carbon source and a “composite microbial agent containing cellulose-degrading and nitrogen-fixing strains.”
However, key details are missing:

Number of replicate reactors per treatment (n = ?).
Exact inoculum dose (CFU/g or mL/kg of compost).
Composition of the inoculum: is it a mixed culture from mangrove sediments? Is Brevibacillus sp. P1N2 the main strain? Are there others and in what proportion?

Suggestions

Clearly state the number of composting units per treatment and whether results represent means of replicates.
Provide inoculum characteristics (e.g., 10⁸ CFU/g, applied at X g/kg of substrate) so that other groups can reproduce the process.
Indicate initial C/N ratio and moisture of the composting mixture (filter mud + bagasse), not only of the individual feedstocks.

3.2. Microbial sequencing (Sections 2.3 and 2.5)

For metagenomic sequencing of mangrove sediments and compost samples, the manuscript states that three biological replicates were included per habitat type and that α-diversity indices were calculated.
However, it is not clear:

How many compost samples per treatment and per time point were sequenced.
Whether sequencing data have been deposited in a public repository (e.g., NCBI SRA) with accession numbers.

Suggestions

Specify sample numbers and time points for compost sequencing.
Provide accession numbers or clearly state that data will be deposited, as many journals require open access to sequencing data.

3.3. Pot experiment (Section 2.6)

Important aspects are not described in enough detail:

Number of pots per treatment (replicates).
Soil type and baseline properties (only briefly mentioned later).
Amount of compost or fertilizer applied per pot (g/pot or equivalent t/ha).
Growth conditions (temperature, light, watering regime).
Statistical design (completely randomised? blocks?).

Suggestions

Add a clear description of the experimental design, including replication (e.g., n = 4 pots per treatment), randomisation and statistical analysis plan.
Specify exact application rates of compost and fertilizers.
Indicate which software and tests were used for statistical comparisons (ANOVA, post-hoc tests, etc.).

Results and Discussion – interpretation and quantification

The narrative is generally logical and well connected to the literature, but certain aspects can be improved.

4.1. Statistical analysis and significance

Many results are described as “significantly” higher or lower (e.g., OM reduction, yield increase >25%), but no p-values, error bars or letters of significance are shown in the figures.

Suggestions

Apply appropriate statistical tests (e.g., one-way ANOVA followed by Tukey’s test) to key variables (OM, EC, C/N, yield, biomass).
Add standard deviation/error bars and indicate statistically different groups with letters or symbols.
Avoid using the word “significant” in the text unless backed by a statistical test.

4.2. Claims about aromatic compounds and sulfur behaviour

The manuscript states that decreased hydrogen and changes in C/O ratios indicate an increase in aromatic species such as naphthalene and anthracene, and that rising sulfur content implies reduced H₂S emissions.
However, these specific compounds and gaseous emissions were not directly measured.

Suggestions

Rephrase these statements more cautiously, presenting them as inferred tendencies rather than demonstrated facts. For example:

“The increase in C/H ratio suggests a higher degree of aromaticity, possibly associated with polycyclic structures.”
“The higher sulfur content in the solid phase may indicate retention of sulfur, which could be associated with lower H₂S loss, although gas emissions were not directly measured.”

4.3. Microbial succession and inoculant role

The discussion of the successional pattern (Ochrobactrum/Acinetobacter → Bacillus/Sphingobacterium → Nocardiopsis/rhizobia) is clear and well referenced.
However, because the composting system was also amended with sugarcane bagasse, it would be useful to discuss to what extent the observed changes are due to the inoculant vs the change in substrate composition.

Suggestions

Include a short paragraph acknowledging that both inoculation and addition of bagasse affect the community and that it is not always possible to fully separate their effects in this design.

4.4. Pot experiment – presentation of agronomic benefits

The text reports that bio-augmented compost increases yield by over 25% vs control and ~18–20% vs other fertilizers.
These percentages are convincing but need numerical context (mean values, standard deviations, n) and statistical support, as noted above.

Suggestions

Provide a table with mean ± SD for yield and other measured plant traits, plus p-values.
Explicitly state in the text which comparisons are statistically significant.

Language, style and minor issues

The English is generally clear and the manuscript is easy to follow, but there are numerous minor errors and formatting issues that should be corrected.

5.1. Typographical and spacing errors

Examples include:

“TThe sugar industry…” (double T).
“E ficiency”, “45days”, “Shanon” instead of “Shannon”.
Odd spaces in e.g. “China’s Sugar Capital”, “license s/by/4.0/”.

These likely arise from formatting but should be fixed in the final version.

5.2. Section numbering

The text jumps from Section 3.1.2 directly to 3.1.5, which suggests that intermediate subsections were removed without renumbering. This may confuse readers and should be corrected.

5.3. Long sentences and style

Some sentences, especially in the Introduction and metagenomics discussion, are quite long and could be split to improve readability.
A careful language polish by a fluent speaker or professional editor would help remove residual awkward phrases and ensure consistency in tense and terminology.

5.4. Author contributions and abbreviations

Verify that all author initials in the “Author Contributions” section match the names in the author list and that there are no typos.
Ensure all abbreviations (e.g., OM, EC, TKN, SoF, etc.) are defined at first use and used consistently.

Conclusions

The conclusions are well aligned with the results and emphasize the potential of mangrove-derived microbial inoculants for upgrading sugar filter mud composting and improving crop productivity. To further strengthen this section, the authors might:

Add a brief limitations statement (e.g., pilot-scale reactors, single crop, economic aspects not evaluated).
Include a short future perspectives paragraph (field-scale trials, application to other crops or organic wastes, assessment of long-term soil health).

Comments on the Quality of English Language

The overall English is generally clear and the manuscript is understandable. However, there are several minor grammatical issues, typographical errors, and some overly long sentences. I would therefore recommend a careful language polish by a fluent speaker or professional editing service to improve readability and ensure consistency in terminology and formatting.

Author Response

Comments 1:

Response 1:

Thank you for pointing this out. The original title better reflects the research content and highlights the key points, though it is somewhat lengthy.

Comments 2:

· Figure 1 combines three panels (a–c: bar plots + phylogenetic distribution + heatmap) on a single page.

· The axis labels, taxa names and legends are very small, especially in the heatmap (panel c), making it hard to identify genera and abundance trends.

Response 2: