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

Van Thang Duong,Peer M Schenk,Simon Quigley,Skye R Thomas-Hall,Faruq Ahmed,Ekaterina Nowak

doi:10.3389/fbioe.2015.00053

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.

Highlights

Microalgae occur widely in a variety of natural and man-made environments, including fresh, brackish, sea and waste water, as well as in soil and on other organisms
A total of 13 samples were collected in October 2012 from the surface and bottom ground of freshwater dams, streams, and ponds in the Northern Territory, Australia
Isolation of Pure Microalgal Strains Single cells were isolated by micropipette on a micromanipulator with an inverted microscope and grown on 96 well-plates before transferred to 100 mL flasks in bold’s basal medium (BBM) for cultivation of pure clonal algal cultures at 25°C, 12:12 h light:dark cycle under fluorescent white light (120 μmol photons m−2s−1), as described previously (Duong et al, 2012; Lim et al, 2012; Salama et al, 2013)

Summary

Introduction

Microalgae occur widely in a variety of natural and man-made environments, including fresh, brackish, sea and waste water, as well as in soil and on other organisms. Most microalgae can be found in freshwater and marine habitats such as lakes, rivers, streams, pond, estuary, and coastal areas. Richmond (2004) reported that there could be about 50,000 species, at present about 30,000 species have been identified and analyzed. Based on the large amount of research, the potential of microalgae’s application to the biofuel industry has increased in recent years. There are many microalgae that can accumulate large amounts of lipids in their cells (Sheehan et al, 1998; Lim et al, 2012). The lipid content depends on the specific algal strain and their growth conditions, with average contents ranging from 2 to 75% of dry weight

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