Isolation and Characterization of Taiwanese Heterotrophic Microalgae: Screening of Strains for Docosahexaenoic Acid (DHA) Production

Abstract

Marine heterotrophic microalgal species which are potentially rich in docosahexaenoic acid (DHA, C22:6n-3) have been found in Taiwan; however, there was a lack of detailed analysis and characterization of these indigenous algae which is needed for the development of commercial applications. Hence, the objective of this study was to screen DHA-rich heterotrophic microalgae species indigenous to Taiwan for commercial purposes. Heterotrophic microalgae from a variety of marine habitats were isolated, cultivated, and then identified according to their 18S rRNA gene sequences and morphological characteristics. A comparison was made of their fatty acid profiles, fatty acid content, and amount of biomass. For the strain with highest DHA yield, the optimal growth conditions were determined in order to establish the best fermentation conditions for scale-up. In this study, 25 heterotrophic microalgal strains were successfully isolated from marine habitats around Taiwan. All of the isolated strains showed a close phylogenic relationship with the Thraustochytriaceae family according to their 18S rRNA gene sequences. GC/MS analysis discerned seven distinctive fatty acid profiles of these strains, with the production of eicosapentaenoic acid (C20:5n-3) ranging from 0.02 to 2.61 mg L(-1), and DHA ranging from 0.8 to 18.0 mg L(-1). An Aurantiochytrium strain BL10 with high DHA production was subsequently chosen for further manipulation. Under optimal growth conditions it could produce up to 59.0 g of dry biomass per liter of culture, with dry biomass containing 73% total fatty acid and 29% DHA, revealing BL10 as an excellent source of microbial DHA.

Local bioprospecting for high-lipid producing microalgal strains to be grown on concentrated municipal wastewater for biofuel production

“…National Renewable Energy Laboratory (NREL) launched the Aquatic Species Program (ASP) in 1978 and collected over 3000 microalgae strains from the west, northwest, and southeastern regions of the continental US, as well as Hawaii to systematically screen for high oil content strains grown under normal or severe conditions (Sheehan et al, 1998). Yang et al (2010) targeted local algal species from four types of marine habitats located in the west side of Taiwan with the aim to screen heterotrophic microalgal strains rich in docosahexaenoic acid (DHA, C22:6n-3). However, bioprospecting and establishment of an adequate microalgae pool specifically for wastewater treatment and algal biofuel production, to the best of our knowledge, has not yet been reported before.…”

Alimentos ricos en ácidos grasos v-3 libres de contaminantes y aptos para vegetarianos, y su importancia en el desarrollo neurológico normal

“…Los thraustochytridos son de la familia Thraustochytriaceae y del orden Thraustochytriales, comprenden los géneros Althornia, Diplophrys, Japonochytrium, Elina, Schizochytrium, Thraustochytrium y Ulkenia, pueden acumular en las paredes y membranas la mitad de su peso en v-3, como reserva de triacilgliceroles 96 . Presentes en todo ambiente marino estudiado de aguas frías y representando alrededor de un 30% de la biomasa 97 . Algunas especies se asocian a animales marinos en una relación de huésped o mutualista 98,99 .…”

Impedance fingerprint selection of DHA-producing photoautotrophic microalgae

“…Several DHA-producing microalgal species were mentioned; for example, Crypthecodinium colnii [8], Aurantiochytrium spp. [9], Schizochytrium limacinum [10], Thraustochytriidae sp., Ulkenia sp. [11], Chlorella sp.…”