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Research Publications (Applied Sciences)

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    Investigation of combined effect of nitrogen, phosphorus and iron on lipid productivity of microalgae Ankistrodesmus falcatus KJ671624 using response surface methodology
    (Elsevier, 2015-02-15) Singh, Poonam; Guldhe, Abhishek; Kumari, Sheena K.; Rawat, Ismail; Bux, Faizal
    Enhancement of lipid accumulation is essential to improve the commercial feasibility of microalgal biodiesel production. An oleaginous microalgal strain, Ankistrodesmus falcatus KJ671624 was evaluated for its potential as a biodiesel feedstock in this study. The collective effect of nutrient (nitrogen, phospho-rous and iron) stresses on the lipid productivity of the selected strain was studied by response surface methodology. The highest lipid content of 59.6% and lipid productivity of 74.07 mg L−1 d−1 was obtained under nutrient stress with nitrogen 750 mg L−1, phosphorus 0 mg L−1 and iron 9 mg L−1. The photosyn-thetic behaviour validates the high lipid productivity under combined nutrient stress condition. Saturated fatty acid composition was increased by 38.49% under selected nutrient stress condition compared to BG11 medium. The enhanced lipid accumulation with suitable lipid profile (C16:0, C18:1, C18:2, C18:3) and biodiesel conversion of 91.54 ± 1.43% achieved in A. falcatus KJ671624 further confirm its potential as a promising feedstock for biodiesel production.
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    Biodiesel synthesis from microalgae using immobilized Aspergillus niger whole cell lipase biocatalyst
    (Elsevier, 2016) Guldhe, Abhishek; Singh, Poonam; Kumari, Sheena K.; Rawat, Ismail; Permaul, Kugen; Bux, Faizal
    Whole cell lipase catalysis and microalgal feedstocks make overall biodiesel synthesis greener and sustainable. In this study, a novel approach of whole cell lipase-catalyzed conversion of Scenedesmus obliquus lipids was investigated for biodiesel synthesis. Microalgal biodiesel was characterized for its fuel properties. Optimization of process parameters for immobilized Aspergillus niger whole cell lipase-catalyzed biodiesel synthesis was carried out. Highest biodiesel conversion of 53.76% was achieved from S. obliquus lipids at 35 °C, methanol to oil ratio of 5:1 and 2.5% water content based on oil weight with 6 BSPs (Biomass support particles). Step-wise methanol addition was applied to account for methanol tolerance, which improved biodiesel conversion upto 80.97% and gave 90.82 ± 1.43% yield. Immobilized A. niger lipase can be used for 2 batches without significant loss in conversion efficiency. Most of the fuel properties of biodiesel met the specifications set by international standards.
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    Biocatalytic conversion of lipids from microalgae Scenedesmus obliquus to biodiesel using Pseudomonas fluorescens lipase
    (Elsevier, 2015-01-31) Guldhe, Abhishek; Singh, Bhaskar; Rawat, Ismail; Perumal, Kugen; Bux, Faizal
    Conversion of microalgal lipids using biocatalyst is a novel and greener approach to produce biodiesel. Free and immobilized lipases from Candida sp. and Pseudomonas fluorescens along with free lipases from porcine pancreas and wheat germ were screened for biodiesel conversion of Scenedesmus obliquus lipids. Among selected lipases from various sources immobilized lipase from P. fluorescens showed superior biodiesel conversion. Optimization of reaction parameters viz. lipase amount, temperature, methanol to oil molar ratio and water content was carried out using response surface methodology. Best conversion of 66.55% was achieved at 35 °C, methanol to oil ratio of 3:1 with 10% enzyme amount and 2.5% water content based on oil weight. To tackle methanol tolerance step-wise methanol addition was applied, which improved biodiesel conversion upto 90.81%. Immobilized P. fluorescens lipase can be used for 4 batches without much loss in conversion efficiency (>95%). Biodiesel produced has the cetane number of 51.77, Calorific value of 37.67 MJ kg−1. Most of the fuel properties of biodiesel met the specifications set by ASTM and EN standards.