Research Express@NCKU - Articles Digest
Research Express@NCKU Volume 29 Issue 8 - October 2, 2015 [ http://research.ncku.edu.tw/re/articles/e/20151002/1.html ]
Rapid and In Vivo Quantification of Cellular Lipids in
Chlorella vulgaris using Near-infrared Raman
Spectrometry
Tsung-Hua Lee, Jo-Shu Chang, Hsiang-Yu Wang
*Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan
University Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan hywang@mail.ncku.edu.tw
Anal. Chem., 2013, 85 (4), pp 2155–2160,DOI: 10.1021/ac3028118
T
he shortage of fossil fuels and their negative impacts to the environments have driven scientists to find alternative energy sources that are renewable and environment-friendly.Among many options, biofuels are considered promising prospects because they are not only renewable but also low in carbon intensity. Microalgae have short growth/harvest cycle, high abundance of cellular lipids, low requirement in land area, and possible abilities in carbon fixation and hydrogen generation; therefore, they have been favorable choices in the biofuels
development with the focal fuel in such processes being biodiesel. As the microalgae-based lipids are the raw materials for biodiesel synthesis, it is crucial to be able to detect and quantify the lipid content in the microalgal biomass. Conventional quantification methods for microalgae cellular lipid are typically invasive, time-consuming, demanding in instrument, or requiring additional reagents. Most methods are not able to provide real-time
information for improving the cultivating parameters that significantly affect the lipid production or for
determining the harvest timing during the large-scale cultivation. In most current studies, the accurate quantity of microalgae lipids can only be obtained after the crop is harvested; hence, the adjustment of cultivation parameters depends solely on experience and large amounts of experiments.
The aim of this study was to develop a rapid, noninvasive, straightforward, and label-free quantification method for microalgae cellular lipids using near infrared (NIR) Raman spectrometry. The characteristic Raman shifts of microalgae lipids were identified and selected shifts were monitored along the nitrogen depletion period. The calibration curve built with signal at 2845-3107 cm-1 was applied to predict the total lipid abundance of two microalgae samples and the predicted values had differences less than 2 wt% from the values measured by the conventional gas chromatography method. The proposed method is undemanding in pretreatment and shortens the time for quantification to less than 1.5 hour. It has great potential in high-throughput screening of microalgae and timely quality control of microalgae culture and biodiesel production.
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