Dataset: TEP concentrations of co-cultures and axenic cultures of Minutocellus polymorphus and particle-associated marine bacteria

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 [Cell abundance dataset]
• suspended microaggregates (aggregates ca. 5-60 μm) [Suspended Microaggregate dataset]
• TEP (Transparent Exopolymeric Particles) [this dataset]

This dataset presents Transparent Exopolymeric Particle (TEP) concentrations. The other measurements can be found in the Related Datasets listed below. 

TEP concentrations in the co-cultures and axenic cultures were determined as described by Passow and Alldredge (1995). 10 mL of glutaraldehyde-fixed culture samples were filtered through duplicate 0.4 µm pore-size polycarbonate membranes (GVS Life Technologies, ME) at a low and constant vacuum pressure (100 mm Hg). The retained TEP was subsequently stained with 0.5 mL of the acidic polysaccharide-specific Alcian Blue (AB) dye (8GX, Sigma-Aldrich), followed by a 0.5 mL rinse with MilliQ water for the removal of excess stain and stored at −40 °C until analysis. Prior to staining, the pre-calibrated 0.02% (w/v) AB working solution that was pH-adjusted with 0.06% (v/v) acetic acid (final pH 2.5) was passed through a 0.2 µm Acrodisc syringe filter (Pall Corporation, NY) to remove the undissolved dye. Membranes were soaked in 6 mL of 80% (v/v) sulfuric acid for 3 h to extract the AB-stained TEP and absorption was then measured using a spectrophotometer (Shimadzu UV-1900i, Shimadzu, Kyoto, JP) at 787 nm. Duplicate stained filters with sterile media functioned as blanks.

TEP concentrations were calculated using a calibration factor of the Alcian-Blue dye determined with xanthan gum (f-factors: 81.70 for experiments with M. adhaerens and 83.83 for experiments with V. thalassae and P. carrageenovora) and expressed in µg of xanthan gum equivalent units (µg XG eq.) as described by Bittar et al. (2018). To compare TEP concentrations between treatments and with other phytoplankton groups, concentrations were normalized to diatom cell abundances and biovolumes, respectively. 

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