High protein- and high lipid-producing microalgae from northern australia as potential feedstock for animal feed and biodiesel - PubMed (original) (raw)

High protein- and high lipid-producing microalgae from northern australia as potential feedstock for animal feed and biodiesel

Van Thang Duong et al. Front Bioeng Biotechnol. 2015.

Abstract

Microalgal biomass can be used for biodiesel, feed, and food production. Collection and identification of local microalgal strains in the Northern Territory, Australia was conducted to identify strains with high protein and lipid contents as potential feedstock for animal feed and biodiesel production, respectively. A total of 36 strains were isolated from 13 samples collected from a variety of freshwater locations, such as dams, ponds, and streams and subsequently classified by 18S rDNA sequencing. All of the strains were green microalgae and predominantly belong to Chlorella sp., Scenedesmus sp., Desmodesmus sp., Chlamydomonas sp., Pseudomuriella sp., Tetraedron caudatum, Graesiella emersonii, and Mychonastes timauensis. Among the fastest growing strains, Scenedesmus sp. NT1d possessed the highest content of protein; reaching up to 33% of its dry weight. In terms of lipid production, Chlorella sp. NT8a and Scenedesmus dimorphus NT8e produced the highest triglyceride contents of 116.9 and 99.13 μg mL(-1) culture, respectively, as measured by gas chromatography-mass spectroscopy of fatty acid methyl esters. These strains may present suitable candidates for biodiesel production after further optimization of culturing conditions, while their protein-rich biomass could be used for animal feed.

Keywords: 18S rDNA sequencing; animal feed; biodiesel; fatty acid methyl esters; microalgae; protein-rich biomass; triacylglyceride.

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Figures

Figure 1

Figure 1

Selected microalgae isolated from the Northern Territory, Australia, observed under a microscope. (A) Scenedesmus sp. NT1d, (B) Chlorella sp. NT8a, (C) Tetraedron caudatum NT5, (D) Scenedesmus dimorphus NT8c, (E) Scenedesmus dimorphus NT8e, (F) Graesiella emersonii NT1e.

Figure 2

Figure 2

Maximum parsimony analysis of taxa of isolated microalgae. Shown are genus, species (if applicable), and strain names, as well as Genbank entry accession numbers. The most parsimonious tree with a length of 96 is shown. The consistency index was 0.761905, the retention index was 0.83871, and the composite index was 0.707661 and 0.639017 for all sites and parsimony-informative sites, respectively. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (200 replicates) is shown next to the branches.

Figure 3

Figure 3

Growth curves of isolated microalgal strains from the Northern Territory. Shown are mean values and SEs from three separately grown cultures each.

Figure 4

Figure 4

Nitrogen depletion in cultivation of Northern Territory microalgae experiments. Shown are mean values and SEs from three separately grown cultures each.

Figure 5

Figure 5

Protein contents (% DW) in five rapidly growing microalgal strains from the Northern Territory, Australia. Shown are mean values and SEs from three separately grown cultures each.

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