Thursday, December 14, 2017

Impressive high school senior joins DROPPS lab to analyze bacterial compositions in the Gulf with sophisticated new equipment

Impressive high school senior joins DROPPS lab to analyze bacterial compositions in the Gulf with sophisticated new equipment                                                                  By Lalitha Asirvadam


High school senior Helen Schawe from Veterans Memorial High School in Corpus Christi, TX, is working on some exciting new research in Dr. Jian Sheng’s lab at Texas A&M University-Corpus Christi. Dr. Sheng is a Co-Principal Investigator in the Dispersion Research on Oil: Physics and Plankton Studies (DROPPS) consortia within the Gulf of Mexico Research Initiative. DROPPS is looking at how dispersants and wave action affected the breakup and fate of the oil and how it affected planktonic and bacterial communities during and after the Deep Water Horizon (DWH) Oil Spill. Helen joined Dr. Sheng’s team over the summer and continues to work on the project when she finds time after school and between swim practices. Helen has been working with different bacterial samples from the Deep Water Horizon site and other areas in the Gulf of Mexico in order to assess growth behavior and particulate formation with different bacterial compositions and oil/dispersant concentrations.
Dr. Sheng brought Helen onto the project as an intern in May to look at how dispersants influence bacterial growth and oil degradation. Along with postdoctoral researcher Andrew White, Helen works with six different samples where bacteria compositions may have been affected by the oil - one set from the DWH wellhead and from the water column above; one from the Louisiana Delta sediments and the water column above, and one from Port Aransas sediments and the water column above it. DROPPS researcher and UTMSI professor Zhanfei Liu profiled the samples.

Sample compositions consisted of oil alone, oil with dispersant, and dispersant alone. They are looking at how well bacteria grow in these different conditions and how these conditions affect particulate and bacterial aggregate formation.  Helen is also looking at rheological changes. Bacteria produce extracellular polymerica substances (EPS), which consist of proteins, carbohydrates, nucleic acids and other materials. Using a sophisticated Dynamic Shear Rheometer (DSR), they measure the effective viscosity increases and the viscoelasticity of the medium as the bacteria grow. She is also working with a spectrophotometer which is used daily to measure the optical density of the bacteria samples in order to chart their growth over time. Optical density is a measurement of how much light is absorbed by the bacteria and other particles in the culture. Helen also used a phase contrast microscope to assess bacterial morphology and motility. More recently, she has used a dynamic light scattering (DLS) analyzer to measure particle sizes in bacterial samples in order to assess the impact of dispersant on particulate size and formation.

Dr. Sheng is very excited about some of the preliminary findings. They found that with oil plus dispersant, much smaller particles (80-100 nanometers) were produced and the culture growth was much faster than cultures grown with crude oil only. Helen is cataloging the samples that s how the spike in 80-100 nanometers, a unique finding since this not visible in traditional microscopes. Dr. Sheng says this finding is important since these kinds of observations are lacking. These are the “ingredients to promote marine snow”, he says, and since 20-30% of the oil from the BP Oil Spill is still unaccounted for, this could be an answer as to what happened to some of it. Marine snow is organic debris that falls from the upper water column to the deep ocean and can eventually land on the seafloor. These bacterial aggregates may be a perfect vehicle to transport oil down to the seafloor.

Helen submitted a poster detailing this research and will present it at the next Gulf of Mexico Oil Spill & Ecosystem Science Conference in February 2018 in New Orleans, Louisiana. She is graduating from Veteran’s Memorial High School in the spring of 2018 in the top 10% of her class. She has her sights set on Northwestern University, the University of Texas, the University of Pennsylvania, and Massachusetts Institute of Technology. She wishes to study mechanical engineering.