Dataset: Laboratory data on cell abundance of Minutocellus polymorphus in experiments measuring TEP and production of microaggregates

In this study, one diatom and three bacteria species were grown and measured.  Minutocellus polymorphus were incubated with or without the addition of bacteria in flasks and sampled throughout their growth (representative of bloom conditions), to determine the production of transparent exopolymeric particles (TEP) and the formation of micro-aggregates, and in roller tanks to investigate the formation of sinking aggregates (representative of end of bloom conditions).  Additional details are in Cruz & Neuer, 2022.  

Two growth experiments were carried out independently:
1. Growth experiment 1 with the addition of Marinobacter adhaerens
2. Growth experiment 2 with the addition of Pseudoalteromonas carrageenovora and Vibrio thalassae 

Stock cultures of marine Minutocellus polymorphus (CCMP497, National Center for Marine Algae and Microbiota, NCMA) were maintained in L1 medium prepared in artificial seawater and incubated in an environmental growth chamber (Conviron) at 23 ± 1 °C.   Stock cultures of Vibrio thalassae (DSM102810, DSMZ-German Collection of Microorganisms and Cell Cultures GmbH), Pseudoalteromonas carrageenovora (DSM6820, DSMZ), and Marinobacter adhaerens HP15 were maintained on Marine Agar (BD Difco 2216, Becton Dickinson, NJ; ZoBell, 1941) plates at 23 ± 1 °C. 

Triplicate cultures of Minutocellus polymorphus (CCMP497) with and without the addition of known particle-associated marine bacteria (M. adhaerens, P. carrageenovora, and V. thalassae) were sampled every other day for 19-23 days for the quantification of:

• single cells [this dataset]
• suspended microaggregates (aggregates ca. 5-60 μm) [Suspended Microaggregates dataset]
• TEP (Transparent Exopolymeric Particles) [TEP Concentration dataset]

This dataset contains single cell abundances of diatoms and bacteria determined using epifluorescence microscopy. The other measurements can be found in the Related Datasets section below.  

Cell abundances in the cultures were determined with the use of epifluorescence microscopy (Carl Zeiss AxioScope.A1). Glutaraldehyde-fixed samples were stained with the nucleic acid dye DAPI (4′,6-diamidino-2-phenylindole, 0.03 M, Sigma-Aldrich), and filtered onto gray 0.2 µm pore-size polycarbonate membranes (GVS Life Technologies, ME). Chlorophyll-a emission by M. polymorphus cells and DAPI-stained bacteria were visualized under 450–490 nm excitation and 380–400 nm, respectively.

Suspended microaggregates (i.e., non-sinking particles with an equivalent spherical diameter of 5-60 microns) were quantified using a Multisizer 3 Particle Counter.  TEP concentrations were determined as in Bittar et al. (2018). The stocks of Alcian-Blue dye used for TEP quantification had calibration factors (or f-factors) of 81.70 for experiments with M. adhaerens and 83.83 for experiments with P. carrageenovora and V. thalassae.

For additional Methods details, see Cruz & Neuer, 2022.