Precipitation of calcium carbonate mineral induced by viral lysis of cyanobacteria: evidence from laboratory experiments

Xu, Hengchao; Peng, Xiaotong; Bai, Shijie; Ta, Kaiwen; Yang, Shouye; Liu, Shuangquan; Jang, Ho Bin; Guo, Zixiao

doi:https://doi.org/10.5194/bg-16-949-2019

Articles | Volume 16, issue 4

https://doi.org/10.5194/bg-16-949-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-16-949-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 4

Research article

|

28 Feb 2019

Research article |

| 28 Feb 2019

Precipitation of calcium carbonate mineral induced by viral lysis of cyanobacteria: evidence from laboratory experiments

Hengchao Xu, Xiaotong Peng, Shijie Bai, Kaiwen Ta, Shouye Yang, Shuangquan Liu, Ho Bin Jang, and Zixiao Guo

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Final revised paper (published on 28 Feb 2019)
Supplement to the final revised paper
Preprint (discussion started on 02 May 2018)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'review', Anonymous Referee #1, 15 May 2018
- AC1: 'Precipitation of Calcium Carbonate Mineral Induced by Viral Lysis of Cyanobacteria', Xiaotong Peng, 05 Jul 2018
RC2: 'Cyanophage induced carbonate precipitation from lysed cyanobacteria', Anonymous Referee #2, 16 May 2018
- AC2: 'Precipitation of Calcium Carbonate Mineral Induced by Viral Lysis of Cyanobacteria', Xiaotong Peng, 05 Jul 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (02 Aug 2018) by Lennart de Nooijer

AR by Xiaotong Peng on behalf of the Authors (06 Sep 2018) Author's response Manuscript

ED: Reconsider after major revisions (16 Oct 2018) by Lennart de Nooijer

ED: Referee Nomination & Report Request started (16 Oct 2018) by Lennart de Nooijer

RR by Anonymous Referee #1 (12 Nov 2018)

RR by Anonymous Referee #2 (14 Nov 2018)

Suggestions for revision or reasons for rejection

After reviewing the authors’ responses to the reviewers’ comments on the original submission and the revised manuscript, the authors addressed some of the reviewers’ comments and suggestions adequately but there are several remaining issues which must be addressed. Most of these issues will not be listed in this review because there are a few items on which the manuscript’s hypotheses and data interpretations are based that cannot be supported. These major or core issues are the input data and constraints for the geochemical modeling using PHREEQC and the lack of data showing definitive lysis of the cyanobacterial cells by cyanophage. Based upon the statements in the Abstract and Discussion the reliability of geochemical data and active lysing of cyanobacterial cells by cyanophage are the two most critical aspects of this study and on which the authors base their conclusions. Comments on the issues associated with these concepts are listed below:

1. All experiments were conducted in a complex medium (i.e., f/2 medium). Therefore, all data from the geochemical modeling using PHREEQC and seawater carbonate chemistry using CO2calc are suspect when extending the data to natural seawater or freshwater. A reviewer’s comment on the original submission requested the actual PHREEQC code and variable entries and respective concentrations (or activities) (i.e., the basis) be included in the revised manuscript. The code and basis entries were not included in the revised manuscript. This is critically important because the resulting data and interpretations are dependent upon what was entered into PHREEQC and the options the authors used to constrain the program’s outputs. For example, the relevance and reliability of PHREEQC outputs are totally dependent upon how the components of f/2, as listed in Table 1, were entered into PHREEQC. The saturation indices (SI) for the calcium carbonate polymorphs listed in Table 2 and Table S1 are not relevant to natural freshwater or seawater, only to f/2 medium. With regard to using the CO2calc, the use of this program is not appropriate for this study because it is optimized for calculations of equilibrium carbonate chemistry variables in seawater and, to a lesser degree, freshwater.

2. Cyanobacteria vs cyanophage data (Figure 2A): One of the recurring concepts in the original and revised manuscript is the role cyanophage play in changing the carbonate chemistry in a culture of cyanobacteria. By lysing the host cyanobacterial host cell, the infecting cyanophage not only release the intracellular contents of the host cell (e.g., HCO3-) but also relatively high numbers of progeny cyanophage. As this cycle of (1) host cell infection, (2) cyanophage controlling host cell synthesis processes, (3) synthesis of infectious progeny cyanophage and (4) host cell lysis and release of more cyanophage progresses through a contained culture as described in this study, there should be a point in the cyanobacterial growth curve where the cell numbers significantly decrease with a concomitant increase in the number of cyanophage. The graphed data in Figure 2A does not show these trends in the respective counts. Therefore, the contribution of cyanophage lysis of host cyanobacterial cells to the changes in carbonate chemistry variables cannot be supported as Figure 2A shows no significant reduction in cyanobacterial counts (i.e., no significant viral lysis) over a 14 day period of incubation.

3. Table S1: For natural freshwater and seawater systems the values listed for pH, pCO2, CO3 and HCO3 are unrealistic when compared to data from the same variables from natural seawater. For example, the typical range for pCO2 should be between 140-770 micro-atm. The large deviations of these data sets from what is typically measured may be the result of improper geochemical modelling with PHREEQC. (See Comment #1)

The authors have not described a laboratory system from which the data can be reliably extended to natural seawater or freshwater systems as they propose. The experimental design is more applicable to an industrial setting where cyanobacteria are used to scrub CO2 from product streams and/or precipitate carbonate-based minerals on the surfaces of the cells and/or viruses in those product streams or perhaps a solid phase reactor.

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ED: Publish subject to minor revisions (review by editor) (16 Nov 2018) by Lennart de Nooijer

ED: Reconsider after major revisions (16 Nov 2018) by Lennart de Nooijer

AR by Xiaotong Peng on behalf of the Authors (14 Dec 2018) Author's response Manuscript

ED: Publish as is (11 Feb 2019) by Lennart de Nooijer

AR by Xiaotong Peng on behalf of the Authors (18 Feb 2019) Author's response Manuscript

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Short summary

Viruses have been acknowledged as important components of the marine system for the past 2 decades, but understanding of their role in the functioning of the geochemical cycle remains poor. Results show viral lysis of cyanobacteria can influence the carbonate equilibrium system remarkably and promotes the formation and precipitation of carbonate minerals. Amorphous calcium carbonate (ACC) and aragonite are evident in the lysate, implying that different precipitation processes have occurred.