Abstract:

Dynamic Laser Scattering technique was used to measure bacterial exopolymeric substances aggregation behavior. This dataset includes particle size for particles > 0.22 microns for different liquids (artificial seawater at 35 psu, milli-Q water with 18 mega-ohm cm at 25 deg C, and salt water at 35 psu with all cations replaced by Na+) under different conditions (dark = 1 hr with no light exposure and light = 1 hr of exposure to sunlight).

Suggested Citation:

Chiu, Meng-Hsuen (James), Chin, Wei-Chun. 2017. EPS mechanisms which aid in aggregation: Light-induced aggregation of bacterial exopolymeric substances using DLS. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7J67F1X

Publications:

Sun, L., Xu, C., Zhang, S., Lin, P., Schwehr, K. A., Quigg, A., … Santschi, P. H. (2017). Light-induced aggregation of microbial exopolymeric substances. Chemosphere. doi:10.1016/j.chemosphere.2017.04.099

Purpose:

To test the hypothesis that light-induced bacterial aggregates are larger than any that may form in the dark.

Data Parameters and Units:

ASW=artificial seawater; MQ=milli-Q water with 18 mega-ohm cm at 25 oC; SW=salt water with the same salinity (35) as ASW but with all cations replaced by Na+) Dark= particles > 0.22 microns after 1 hr with no exposure to light Light=irradiated EPS particles > 0.22 microns after exposure to 1 hr of sunlight in glass flask Replicates 1-6 = S1, S2, ….S6 Time in hours Particle size in microns

Methods:

Samples were shaken, and filtered through a 0.22-μm Millipore membrane (pre-washed with 0.1N HCl) before use. Aliquots were then poured directly into scattering cells. The scattering cells were positioned in the goniometer of a Brookhaven laser spectrometer (Brookhaven Instruments, NY, USA). The polymer assembly was monitored for 8 ~ 10 days by analyzing the scattering fluctuations detected at a 45 degree scattering angle. The autocorrelation function of the scattering intensity fluctuations was averaged over a 10-min sampling time, using a Brookhaven BI 9000AT auto correlator. Particle size distribution was calculated by the CONTIN method. Each measurement was taken in triplicate in 10 ml at room temperature. A calibration of the DLS method was conducted using standard suspensions of latex microspheres.

Instruments:

Brookhaven BI 9000AT auto correlator

Individual Files: