Abstract:

Both phytoplankton and bacteria secrete extracellular enzymes actively that help them degrade the complex molecules to provide them simple carbon (sugars) and nitrogen (amino acids) molecules that can be easily assimilated. This process supports bacterial growth on exopolymeric substances (EPS) and helps support their cell division. However, this process does not lead to depletion of EPS, as only a fraction is consumed by bacteria. Due to the sticky nature of the EPS, the newly formed bacteria will tend to adhere to the EPS, and this will lead to the eventual formation and increase in the size of aggregates. To test this, we added DCB (2,6-dichlorobenzonitrile; an inhibitor of polysaccharide production in diatoms) to Thalassiosira pseudonana in the presence and absence of oil. This dataset contains the SEM micrographs documenting the phytoplankton, bacterial, and EPS changes in morphology. The confocal laser scanning microscopy (CLSM) micrographs depicting the changes in EPS and microbes showing the effects of DCB and WAF are available under GRIIDC UDI R6.x807.000:0028. The algal and bacterial growth in terms of enzyme assays, microbial cell counts, monosaccharide concentrations, and photosynthesis data at different WAF concentrations are available under GRIIDC UDI R6.x807.000:0022.

Suggested Citation:

Manoj Kamalanathan, Antonietta Quigg. 2018. Microcosm: SEM micrographs of generation of exopolymeric substances (EPS) by phytoplankton and bacteria with and without polysaccharide inhibitor at various concentrations of WAF. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7FF3QZ9

Publications:

Kamalanathan, M., Chiu, M.-H., Bacosa, H., Schwehr, K., Tsai, S.-M., Doyle, S., … Quigg, A. (2019). Role of Polysaccharides in Diatom Thalassiosira pseudonana and its Associated Bacteria in Hydrocarbon Presence. Plant Physiology, 180(4), 1898–1911. doi:10.1104/pp.19.00301

Purpose:

To visually document the phytoplankton, bacterial, and EPS changes in morphology with and without DCB and the effects of different WAF concentrations.

Data Parameters and Units:

SEM micrographs for four experiments: (1) control, (2) control and DCB, (3) WAF, and (4) WAF and DCB

Methods:

Thalassiosira pseudonana (CCMP 1335) was obtained from the National Center for Marine Algae and Microbiota (NCMA). The WAF was prepared by adding oil (400 µL.L-1) into sterile f/2 growth media and stirred overnight in the dark. T. pseudonana cultures were inoculated in control f/2 medium (6 × 1000 mL) and WAF medium (6 × 1000 mL) with approximately 2.6 × 104 cells mL−1. DCB solution prepared in Dimethyl sulfoxide (DMSO) was added to half of the both Control and WAF treatments (3 out of 6 × 1000 mL) to obtain a final concentration of 150 µM. T. pseudonana were incubated for 24-h prior to the addition of DCB to allow growth. For scanning electron microscopy, samples were fixed using 3.5% formaldehyde and then washed with PBS followed by deionized water rinse. This was followed by dehydration of the samples using 20%, 40%, 60%, 80%, and 100% methanol. A CO2 critical point dryer was used to remove any residual solvents. A thin layer of Au was finally deposited on these substrates. Images were then acquired by Gemini SEM 500, Zeiss.

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