Faruq Ahmed

Profiling of carotenoids and antioxidant capacity of microalgae from subtropical coastal and brackish waters.

Carotenoids are associated with various health benefits, such as prevention of age-related macular degeneration, cataract, certain cancers, rheumatoid arthritis, muscular dystrophy and cardiovascular problems. As microalgae contain considerable amounts of carotenoids, there is a need to find species with high carotenoid content. Out of hundreds of Australian isolates, 12 microalgal species were screened for carotenoid profiles, carotenoid productivity, and in vitro antioxidant capacity (total phenolic content (TPC) and ORAC). The top four carotenoid producers at 4.68-6.88 mg/g dry weight (DW) were Dunaliella salina, Tetraselmis suecica, Isochrysis galbana, and Pavlova salina. TPC was low, with D. salina possessing the highest TPC (1.54 mg Gallic Acid Equivalents/g DW) and ORAC (577 μmol Trolox Equivalents/g DW). Results indicate that T. suecica, D. salina, P. salina and I. galbana could be further developed for commercial carotenoid production.

High Protein- and High Lipid-Producing Microalgae from Northern Australia as Potential Feedstock for Animal Feed and Biodiesel

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.

Effect of drying, storage temperature and air exposure on astaxanthin stability from Haematococcus pluvialis

Astaxanthin is a powerful antioxidant with various health benefits such as prevention of age-related macular degeneration and improvement of the immune system, liver and heart function. To improve the post-harvesting stability of astaxanthin used in food, feed and nutraceutical industries, the biomass of the high astaxanthin producing alga Haematococcus pluvialis was dried by spray- or freeze-drying and under vacuum or air at -20°C to 37°C for 20weeks. Freeze-drying led to 41% higher astaxanthin recovery compared to commonly-used spray-drying. Low storage temperature (-20°C, 4°C) and vacuum-packing also showed higher astaxanthin stability with as little as 12.3±3.1% degradation during 20weeks of storage. Cost-benefit analysis showed that freeze-drying followed by vacuum-packed storage at -20°C can generate AUD

Algal Biorefinery: Sustainable Production of Biofuels and Aquaculture Feed?

600 higher profit compared to spray-drying from 100kgH. pluvialis powder. Therefore, freeze-drying can be suggested as a mild and more profitable method for ensuring longer shelf life of astaxanthin from H. pluvialis.

UV‐C mediated rapidcarotenoid induction and settling performance of Dunaliellasalina and Haematococcus pluvialis

With increased human consumption, fossil fuels and global fish stocks are rapidly depleting which has caused significant environmental and ecological damage. Current bioenergy crops compete with arable land or biodiverse landscapes, and current aquaculture is heavily dependent on wild fish for aquaculture feed. Microalgae are miniature biochemical factories and, in terms of global ecological footprint, could make a greater contribution than terrestrial plants in fixing CO2 and converting solar energy into chemical energy and nutrients. With recent research progress in algal cultivation and biotechnology, microalgae have great potential as sustainable feedstock for the production of biofuels and aquaculture feed with a number of environmental benefits. This book chapter will review the advances in the use of microalgae as part of a multiple product biorefinery for generation of renewable biofuels and aquaculture feed.

Comparison of astaxanthin accumulation and biosynthesis gene expression of three Haematococcus pluvialis strains upon salinity stress

Microalgae are primary producers of organic pigments carotenoids in aquatic environments. However, commercial‐scale microalgae application for high value carotenoids production is rarely economical due to the cost‐effectiveness of carotenoid induction and microalgal harvesting process. Here, we present a novel approach, using a small dose of externally applied UV‐C radiation, to rapidly induce unsaturated fatty acids and carotenoid biosynthesis in Dunaliella salina and Haematococcus pluvialis, and also to significantly promote their swimming cells settling for primary dewatering. The amount of total carotenoids and β‐carotenoid were doubled in 24 h on D. salina upon 50 mJ/cm2 of UV‐C radiation, whereas the astaxanthin yield of H. pluvialis was increased five times in 48 h at 30 mJ/cm2. Meanwhile, 95% of algal cells of D. salina and H. pluvialis settled in 15 h and 2 h, respectively. This novel technique represents a convenient, time‐saving and cost‐effective method for commercial microalgal carotenoids production. Biotechnol. Bioeng. 2015;112: 2106–2114.