Publications by authors named "Dy'mon Walker"

2 Publications

  • Page 1 of 1

Impact of Zero-Valent Iron Nanoparticles on Transesterified Lipids and Fatty Acid Methyl Esters.

ACS Omega 2020 Jun 20;5(21):12166-12173. Epub 2020 May 20.

Department of Biology, Morgan State University, 1700 East Cold Spring Lane, Baltimore, Maryland 21251, United States.

Efforts to enhance the transformative potential of biofuels is an important step to achieving an environment-friendly and sustainable energy source. is an ideal third-generation biofuel agent due to its ability to produce lipids and desirable essential fatty acids. In this study, the impact of Nanofer 25s nanoscale zero-valent iron nanoparticles (nZVIs) on total lipid content and fatty acid composition of strains SF33 and B481 was investigated. We observed significant increases ( < 0.05) in the growth of treated with 0.2-1.6 mg L Nanofer 25s, indicating that trace concentrations of nZVIs were not toxic to the organism. Chlorophyll , carotenoids, and phycobiliprotein levels were not altered in treated with nZVIs ranging from 0.4 to 1.6 mg L, confirming that these concentrations did not negatively impact photosynthetic efficacy. In addition, Nanofer 25s ranging from 0.2 to 1.6 mg L had an optimal impact on SF33 and B481 total lipid content. We identified significant increases in unsaturated fatty acid methyl esters (FAMEs) from Nanofer 25s-treated transesterified lipids. Theoretical chemical and physical biofuel properties revealed a product with elevated cetane number and oxidative stability for both strains. Scanning electron microscopy and energy-dispersive X-ray spectroscopy validated the localization of nZVIs. Our findings indicate that Nanofer 25s nZVIs significantly enhance total lipid content and essential FAMEs, thus offering a promising approach to augment the potential of the cyanobacterium as a large-scale biofuel agent.
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http://dx.doi.org/10.1021/acsomega.0c00566DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7271364PMC
June 2020

Microcystin Levels in Selected Cyanobacteria Exposed to Varying Salinity.

J Water Resour Prot 2019 Apr;11(4):395-403

Department of Biology, Morgan State University, Baltimore, MD, USA.

Microcystins produced by cyanobacteria pose a great threat to human health by releasing toxins upon cell death. In the present study, we studied microcystin production in the cyanobacterial strains (B629 and 2949) and (SF33) exposed to 1, 2 and 4 g/L sodium chloride (NaCl). Cultures grown for 7 days in BG11/HEPES medium were pelleted, re-grown in the corresponding NaCl levels, and enzyme linked immunosorbent assay (ELISA) performed. ELISA assays revealed enhanced microcystin production in B629 exposed to 4 g/L NaCl and 29414 exposed to 2 and 4 g/L NaCl, after growth in the corresponding NaCl levels for 14 days. We observed a significant decrease (p >0.05) in microcystin levels in the control strains after exposure to NaCl for 5 days. After exposure to 1, 2, or 4 g/L NaCl for 10 days, no microcystin release was observed in B629, 29414 or F. SF33. Sodium dodecyl sulfate polyacrylamide gel electrophoresis identified the presence of an additional band at 120 - 130 kDa in B629 exposed to 2 and 4 g/L NaCl, and at 14 kDa in cultures amended with 1 and 2 g/L NaCl as well as the untreated control, indicating that exposure to salinity induces alterations in protein expression.
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http://dx.doi.org/10.4236/jwarp.2019.114023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7010315PMC
April 2019