Dawn E. Lewis

Discrimination of bacteria from Jamaican bauxite soils using laser-induced breakdown spectroscopy

Soil bacteria are sensitive to ecological change and can be assessed to gauge anthropogenic influences and ecosystem health. In recent years, there has been a significant increase in the focus on new technologies that can be applied to the evaluation of soil quality. Laser-induced breakdown spectroscopy (LIBS) is a promising technique that has been used for the investigation and characterization of explosives, solids, liquids, gases, biological and environmental samples. In this study, bacteria from un-mined and a chronosequence of reclaimed bauxite soils were isolated on Luria–Bertani agar media. Polymerase chain reaction amplification of the bacterial 16S rDNA, sequencing, and phylogenetic analysis were applied to each isolated soil bacteria from the sample sites resulting in the identification and classification of the organisms. Femtosecond LIBS performed on the isolated bacteria showed atomic and ionic emission lines in the spectrum containing inorganic elements such as sodium (Na), magnesium (Mg), potassium (K), zinc (Zn), and calcium (Ca). Principal component analysis and partial least squares regression analysis were performed on the acquired bacterial spectra demonstrating that LIBS has the potential to differentiate and discriminate among bacteria in the un-mined and reclaimed chronosequence of bauxite soils.

Metagenomic Assessment of the Eastern Oyster-Associated Microbiota

ABSTRACT Bacteria associated with the Eastern oysters (Crassostrea virginica) native to Apalachicola Bay, FL, were investigated using 16S rRNA gene amplicon metagenomic sequencing which revealed that the oyster microbiome was predominated by Cyanobacteria and Proteobacteria. We also found that the oyster tissues were predominated by the pathogenic and symbiotic Photobacterium spp. (formerly known as Vibrio damselae).

Regional discrimination of oysters using laser-induced breakdown spectroscopy

It is well known that eastern oysters (Crassostrea virginica) are bio-indicators and can be used to determine the elemental composition of an estuarine system. Laser-induced breakdown spectroscopy (LIBS) has been successfully used for the detect of trace elements in various environmental matrices. In this work, LIBS was used to characterize oysters collected from a total of six sites in two different coastal estuarine reserves – Grand Bay, Mississippi (4 sites) and Apalachicola Bay, Florida (2 sites). Multiple ionic and neutral elemental species of Al, C, Ca, Cu, Fe, K, Mg, Na, Si, Sr, and Zn were observed through LIBS spectral analysis of the harvested oysters. Principal component analysis, discriminant function analysis, and hierarchical cluster analysis were applied to a data matrix of identified elemental lines resulting in intra- and inter-site clustering of the oysters according to their geographical origin.