Publications by authors named "Behnam Tabatabai"

8 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

Nanoparticle-mediated Impact on Growth and Fatty Acid Methyl Ester Composition in the Cyanobacterium .

Bioenergy Res 2019 Jun 8;12:409-418. Epub 2019 Mar 8.

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

Insufficient light supply is a major limitation in cultivation of cyanobacteria for scaled up biofuel production and other biotechnological applications, which has driven interest in nanoparticle-mediated enhancement of cellular light capture. In the present study, wild type (Fd33) and halotolerant (HSF33-2) strains were grown in solution with 20, 100, and 200 nm-diameter gold nanoparticles (AuNPs) to determine their impact on biomass accumulation, pigmentation, and fatty acid methyl ester (FAME) production. Results revealed a significant increase in growth of Fd33 (0.244 ± 0.006) and HSF33-2 (0.112 ± 0.003) when treated with 200 nm AuNPs. In addition, we observed a significant increase in chlorophyll accumulation in 200 nm AuNP-treated Fd33 (25.7%) and HSF33-2 (36.3%) indicating that NPs enhanced photosynthetic pigmentation. We did not observe any alteration in FAME composition and biodiesel properties of transesterified lipids among all AuNP treatments. Interactions between and AuNPs were visualized using scanning electron microscopy. Energy dispersive X-ray spectroscopy confirmed the presence of AuNPs outside cells with aggregation in high cell density locales. Our findings indicate that nanotechnological approaches could significantly enhance growth of the organism with no negative effect on FAME-derived biodiesel properties, thus augmenting as a potential biofuel agent.
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http://dx.doi.org/10.1007/s12155-019-09966-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6980354PMC
June 2019

Augmenting Fremyella diplosiphon Cellular Lipid Content and Unsaturated Fatty Acid Methyl Esters Via Sterol Desaturase Gene Overexpression.

Appl Biochem Biotechnol 2019 Dec 6;189(4):1127-1140. Epub 2019 Jun 6.

Department of Biology, Morgan State University, 1700 East Cold Spring Lane, Baltimore, MD, 21251, USA.

Cyanobacteria have immense prospective as a platform for renewable energy; however, a major barrier in achieving optimal productivity is the low lipid yield. Fremyella diplosiphon, a model cyanobacterium, is an ideal biofuel agent due to its desirable fatty acid methyl esters (FAMEs). To enhance lipid content, we overexpressed the sterol desaturase (SD) gene in F. diplosiphon B481 wild type by genetic transformation. This effort resulted in a transformant (B481-SD) with a 64-fold increase in the SD gene at the mRNA transcript level, with no loss in growth and pigmentation. The transformant was persistently grown for over 32 generations indicating long-term stability and vitality. We observed 27.3% and 23% increases in total lipid content and unsaturated FAMEs respectively in B481-SD transesterified lipids with methyl octadecadienoate as the most abundant unsaturated component. In addition, we detected an 81% increase in FAME composition in the transformant compared with the wild type. Theoretical physical and chemical properties confirmed a FAME profile with very high cetane number (65.972-67.494) and oxidative stability (50.493-18.66 h) in the engineered strain. Results of the study offer a promising approach to augment F. diplosiphon total lipid content and unsaturated FAMEs, thus paving the way to enhance biofuel capacity of the organism.
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http://dx.doi.org/10.1007/s12010-019-03055-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6884679PMC
December 2019

as a biodiesel agent: Identification of fatty acid methyl esters via microwave-assisted direct in situ transesterification.

Bioenergy Res 2018 Sep 12;11(3):528-537. Epub 2018 May 12.

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

Increasing concerns on environmental and economic issues linked to fossil fuel use has driven great interest in cyanobacteria as third generation biofuel agents. In this study, the biodiesel potential of a model photosynthetic cyanobacterium, , was identified by fatty acid methyl esters (FAME) via direct transesterification. Total lipids in wild type (Fd33) and halotolerant (HSF33-1 and HSF33-2) strains determined by gravimetric analysis yielded 19% cellular dry weight (CDW) for HSF33-1 and 20% CDW for HSF33-2, which were comparable to Fd33 (18% CDW). Gas chromatography-mass spectrometry detected a high ratio of saturated to unsaturated FAMEs (2.48-2.61) in transesterified lipids, with methyl palmitate being the most abundant (C16:0). While theoretical biodiesel properties revealed high cetane number and oxidative stability, high cloud and pour point values indicated that fuel blending could be a viable approach. Significantly high FAME abundance in total transesterified lipids of HSF33-1 (40.2%) and HSF33-2 (69.9%) relative to Fd33 (25.4%) was identified using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry, indicating that robust salt stress response corresponds to higher levels of extractable FAME. Alkanes, a key component in conventional fuels, were present in transesterified lipids across all strains confirming that natural synthesis of these hydrocarbons is not inhibited during biodiesel production. While analysis of photosynthetic pigments and phycobiliproteins did not reveal significant differences, FAME abundance varied significantly in wild type and halotolerant strains indicating that photosynthetic pathways are not the sole factors that determine fatty acid production. We characterize the potential of for biofuel production with FAME yields in halotolerant strains higher than the wild type with no loss in photosynthetic pigmentation.
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http://dx.doi.org/10.1007/s12155-018-9919-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6223314PMC
September 2018

-mediated transformation of for production of transgenic plants.

J Biol Methods 2018 15;5(1):e83. Epub 2018 Jan 15.

Department of Plant Sciences, Sheridan Research and Extension Center, University of Wyoming, Sheridan, WY 82801, USA.

(. ), an oilseed species rich in poly-unsaturated fatty acids, has gained great importance as an industrial oil platform crop in recent years. Despite the potential benefits of for bioenergy applications, limited research has been conducted to improve its agronomic qualities. Hence, a simple and efficient technique for production of transgenic plants is warranted. In the present study, shoot apical meristems of two cultivars (Pl650159 and Pl650161) were transformed with strain 'EHA 105' harboring the enhanced green fluorescent protein (EGFP) and neomycin phosphotransferase II (nptII) genes. After two days of co-cultivation in the dark, explants were transferred to selection medium. Transgenic shoots were identified on the basis of green fluorescence and kanamycin resistance. Shoots were then rooted and transferred to potting mix soil for acclimatization. This protocol describes an efficient method to generate transgenic plants in as little as 4 weeks.
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http://dx.doi.org/10.14440/jbm.2018.208DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6706168PMC
January 2018

Overexpression of hlyB and mdh genes confers halotolerance in Fremyella diplosiphon, a freshwater cyanobacterium.

Enzyme Microb Technol 2017 Aug 24;103:12-17. Epub 2017 Apr 24.

Department of Biology, Morgan State University, Baltimore, MD, USA. Electronic address:

Fremyella diplosiphon is a freshwater cyanobacterium that has great potential as a biofuel agent due to its ability to grow in low light intensity and acclimation to different wavelengths. To enhance its halotolerance for growth in 35gL sodium chloride (NaCl), plasmids harboring hemolysin B (hlyB) and malate dehydrogenase (mdh) genes were transformed into wild type F. diplosiphon (WT-Fd33). Electroporation-mediated overexpression of the genes resulted in two transformants, HSF33-1 and HSF33-2, with 9- and 20-fold increases in hlyB and mdh transcript levels. In addition, up-regulation of proteins at the expected size ranges of 50-60kDa for HlyB and 40-50kDa for MDH was observed. Two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry revealed a protein spot corresponding to HlyB in HSF33-1 with a significant MOWSE score of 164 and 3% sequence coverage, and a spot corresponding to MDH in HSF33-2 gave a significant MOWSE score of 124 with 10% sequence coverage. Physiological evaluation in BG11/HEPES medium and seawater adjusted to 35gL NaCl confirmed that the transformants could thrive in high salinity with no loss of photosynthetic pigments. Results of the study indicate that overexpression of hlyB and mdh genes confer halotolerance in F. diplosiphon, thus maximizing its potential as a large-scale biofuel agent.
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http://dx.doi.org/10.1016/j.enzmictec.2017.04.009DOI Listing
August 2017

Identification of a Halotolerant Mutant via In Vitro Mutagenesis in the Cyanobacterium Fremyella diplosiphon.

Curr Microbiol 2017 Jan 14;74(1):77-83. Epub 2016 Nov 14.

Department of Biology, Morgan State University, Baltimore, MD, 21251, USA.

Energy metabolism and photosynthetic pigment accumulation are affected by salt stress in cyanobacteria leading to cessation of growth. In this study, the effect of salinity on the freshwater cyanobacterium, Fremyella diplosiphon, was investigated and mutagenesis-based efforts were undertaken to enhance salt tolerance. Salinity at a concentration of 10 g/L sodium chloride (NaCl) inhibited growth of wild type F. diplosiphon under white, red, and green light. Efforts to enhance halotolerance resulted in a mutant that could survive in 20 g/L NaCl for 15 generations with no significant reduction in phycobiliproteins (phycocyanin, phycoerythrin, and allophycocyanin) or chlorophyll a. Gene expression measured by quantitative reverse transcription-polymerase chain reaction revealed a three-fold increase in tripartite ATP-independent periplasmic transporters (TRAP) solute receptor transcript in the mutant compared to wild type. Our discovery of a TRAP transporter system in F. diplosiphon and its possible role in salinity response enables growth in brackish waters, which enhances its potential for biotechnological applications.
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http://dx.doi.org/10.1007/s00284-016-1156-zDOI Listing
January 2017