Study on the Attachment of Escherichia coli to Sediment Particles at a Single-Cell Level: The Effect of Particle Size
Round 1
Reviewer 1 Report
Is an interesting article. Perhaps he should be enriched with information in the introductory part.
You should make a comparison of your findings with those of your literature.
Author Response
Response to Reviewer 1 Comments
Point 1: Perhaps he should be enriched with information in the introductory part.
Response 1:
The literature about influence of particle size on bacterial attachment was reviewed in line 48-67. We also add a reference indicating that more microscopical features of particles may also influence bacterial attachment in line 94/95.
Point 2: You should make a comparison of your findings with those of your literature.
Response 2:
Figure 4 showed that the attachment probability measured by our microfluidic experiments had a good predictive ability of partition coefficients and the relation was verified by data from four different references. The corresponding discussion is in line 369-374.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Journal: Water
Title: Study on the attachment of Escherichia coli to sediment particles at a single-cell level: the effect of particle size
Manuscript number: water-486998
In this manuscript, a study on the attachment of bacteria to sediment particles and spherical glass particles, as a model of bacterial contamination in water, was carried out. In fact, attachment to sediment particles affects the transport and fate of bacteria in water and, in turn, has a major effect on the contamination level of water.
During the experiments, both regular spherical glass particles and natural sediment particles, with SiO2 as most significant component in both, were used.
Through a bacterial tracking method together with microfluidic techniques, the attachment of single Escherichia coli cells on the particles was observed.
The above mentioned experiments evidenced that only a small portion of the cells that approach the particles remains attached. Moreover, it is evidenced that attachment probability per approach increased with increasing of surface area, for both sediment and glass particles.
As a conclusion, finer sediments with more surface area have a higher E. coli attachment capacity.
The attachment probability resulted higher on sediment particles than on glass microspheres of equivalent size, suggesting preferential attachment of E. coli to sediment particles.
It is expected to detect a higher number of bacterial cells attached to sediment, with non homogeneus surfaces of particles favouring bacterial colonization. Anyhow, in both sediment particles and spherical glass particles, the behaviour is the same, with similar trends, thus suggesting a real influence of particles size on bacterial adhesion.
In my opinion the manuscript is extremely interesting as the approach of comparison of bacterial attachment to sediment particles and attachment to spherical glass particles focuses on the effect of particles size.
The manuscript offers the opportunity to think in a different way as respect to faecal coliforms contamination in sediments and aquatic environments. In fact, in the manuscript a detailed study of the different factors influencing the different stages of bacterial attachment individually, was highlighted. Actually, investigations at level of cell-particle interactions and comprehension of causes of attachment and detachment, strongly influences future faecal contamination of water. This aspect is thus a critical point which needs to be investigated in the future.
According to the results obtained in this manuscript, granulometric analyses of sediment particles could give suggestions on the attachment probabilities of bacteria and could give informationn when considering level of microbiological contamination in sediments.
Revisions
Line 151: “coli” change to Italic style;
Line 416: “e. Coli” change to “E. coli” and to Italica style;
Line 424: ”Escherichia coli” change to Italic style;
Line 430: “giardia and cryptosporidium” change to “Giardia and Cryptosporidium” and to Italic style;
Lines 442, 446, 448, 462, 482 and 486/487: ”escherichia coli” change to ”Escherichia coli” and to Italic style;
Line 458: “f-specific rna phages” change to “F-specific RNA phages”;
Line 476: “pseudomonas aeruginosa” change to “Pseudomonas aeruginosa” and to Italic style.
Author Response
Response to Reviewer 2 Comments
Points:
Line 151: “coli” change to Italic style;
Line 416: “e. Coli” change to “E. coli” and to Italica style;
Line 424: “Escherichia coli” change to Italic style;
Line 430: “giardia and cryptosporidium” change to “Giardia and Cryptosporidium” and to Italic style;
Lines 442, 446, 448, 462, 482 and 486/487: “escherichia coli” change to “Escherichia coli” and to Italic style;
Line 458: “f-specific rna phages” change to “F-specific RNA phages”;
Line 476: “pseudomonas aeruginosa” change to “Pseudomonas aeruginosa” and to Italic style.
Responses:
Due to revisions, the line numbers change and the exact revision lines are as follows:
Line 153: “coli” has been changed to Italic style;
Line 418: “e. Coli” has been changed to “E. coli” and to Italica style;
Line 426: “Escherichia coli” has been changed to Italic style;
Line 432: “giardia and cryptosporidium” has been changed to “Giardia and Cryptosporidium” and to Italic style;
Lines 444, 448, 450, 465, 489 and 492/493: “escherichia coli” has been changed to “Escherichia coli” and to Italic style;
Line 460: “f-specific rna phages” has been changed to “F-specific RNA phages”;
Line 479: “pseudomonas aeruginosa” has been changed to “Pseudomonas aeruginosa” and to Italic style.
Author Response File: Author Response.docx
