Dataset: Chemotaxis of Vibrio alginolyticus towards live phage-infected/control Synechococcus cells (VIC project)

Data Representing the Net Chemotactic Movement of V. alginolyticus (see the primary data file associated with this dataset)

These data describe the net chemotactic movement of V. alginolyticus in response to axenic Synechococcus WH8102 cells under two conditions:

1) Uninfected Synechococcus WH8102 cells (UI)

2) Synechococcus WH8102 cells infected with the cyanophage S-SSM5 (INF)

V. alginolyticus chemotaxis was evaluated by microscopic imaging in phase contrast using a Zeiss AxioObserver inverted microscope (10x, 0.25NA objective) paired with a CMOS camera (Grasshopper 3, Teledyne FLIR). Images were collected at a frame rate of 1 frame per second for 3,600 seconds. All data were processed using custom MATLAB scripts (version 2021b). The processing summary that results in this data table is:

1) Locate particles using a bandpass filter/peak finding algorithm (available: https://site.physics.georgetown.edu/matlab/)

2) Bin particles according to x-position to examine distribution across the field of view

For each condition (UI and INF), three biological replicates (1,2,3) were conducted using cells sampled from independent cultures of Synechococcus WH8102 at two timepoints: 4- and 8-hours post-infection (HPI). For a total of 12 chemotaxis experiments (these 12 experiments are represented in the 12 tabs of the raw position file V.alg_WH8102cells_PosData_JM.xlsx).

Chemotactic responses (accumulation index) are described by the values given in this dataset for each replicate experiment. The accumulation index is calculated based on bacterial cell positions in every image over the chemotaxis time series (3,600s) and is defined by the equation described in the supplemental file V.alg_WH8102_accumulation_index_details.pdf.

The accumulation index describes directional chemotaxis of the V. alginolyticus population in response to intact Synechococcus WH8102 cells. The analysis found that V. alginolyticus exhibited a stronger chemotactic bias towards Synechococcus WH8102 when they were infected with the cyanophage S-SSM5 which provides support to the overall hypothesis of the project that viral infection of picophytoplankton may result in attraction of heterotrophic microbes thereby altering carbon flux.

Raw Data Representation of the Chemotactic Movement of V. alginolyticus  (see supplemental file V.alg_WH8102cells_PosData_JM.xlsx)

V. alginolyticus chemotaxis was evaluated by microscopic imaging in phase contrast using a Zeiss AxioObserver inverted microscope (10x, 0.25NA objective) paired with a CMOS camera (Grasshopper 3, Teledyne FLIR). Images were collected at a frame rate of 1 frame per second for 3,600 seconds. All data were processed using custom MATLAB scripts (version 2021b). The processing summary is:

1) Locate particles using a bandpass filter/peak finding algorithm (available: https://site.physics.georgetown.edu/matlab/).

2) Bin particles according to x-position to examine distribution across the field of view.

Within each spreadsheet/tab in the supplemental file V.alg_WH8102cells_PosData_JM.xlsx, the first column indicates the timepoint during the chemotaxis experiment (0 to 60 minutes) at which the counts were made. These positional data were collected from each microscopy image taken at a frame rate of 1 frame per second for 3,600 seconds (60 minutes) and were used to calculate the accumulation index as described above. The first column in each spreadsheet denotes the chemotaxis timepoint. Each subsequent column represents a physical width within the microfluidic channel and are used to bin the cell count data. Each microfluidic channel is ~1000μm wide and this distance is divided into 30 bins. The midpoint, or center, of each bin is given in the first row of each column (‘x =’).

As stated, these data were used to calculate the accumulation index and inform directional motility bias of V. alginolyticus in response to Synechococcus cells under uninfected control and cyanophage-infected conditions.