February 21, 2012

Aurantiochytrium sp

Production of lipids containing high levels of docosahexaenoic acid by a newly isolated microalga, Aurantiochytrium sp. KRS101. Hong WK, Rairakhwada D, Seo PS, Park SY, Hur BK, Kim CH, Seo JW. Source Microbe-based Fusion Technology Research Center, Jeonbuk Branch Institute, KRIBB, Jeongeup, Jeonbuk 580-185, South Korea. Abstract In the present study, a novel oleaginous Thraustochytrid containing a high content of docosahexaenoic acid (DHA) was isolated from a mangrove ecosystem in Malaysia. The strain identified as an Aurantiochytrium sp. by 18S rRNA sequencing and named KRS101 used various carbon and nitrogen sources, indicating metabolic versatility. Optimal culture conditions, thus maximizing cell growth, and high levels of lipid and DHA production, were attained using glucose (60 g l⁻¹) as carbon source, corn steep solid (10 g l⁻¹) as nitrogen source, and sea salt (15 g l⁻¹). The highest biomass, lipid, and DHA production of KRS101 upon fed-batch fermentation were 50.2 g l⁻¹ (16.7 g l⁻¹ day⁻¹), 21.8 g l⁻¹ (44% DCW), and 8.8 g l⁻¹ (40% TFA), respectively. Similar values were obtained when a cheap substrate like molasses, rather than glucose, was used as the carbon source (DCW of 52.44 g l⁻¹, lipid and DHA levels of 20.2 and 8.83 g l⁻¹, respectively), indicating that production of microbial oils containing high levels of DHA can be produced economically when the novel strain is used.

February 16, 2012

Harvesting Microalgae

Harvesting Unicellular Micro Algae
Reproduction Algae are able to reproduce sexually and asexually. Sexual reproduction in algae is very rare because of the complexity of gamete transportation and because of this most algae may never get to reproduce sexually. There are two types of asexual reproduction in which algae take part in, they are daughter colony formation and sporulation. In daughter colony formation a group of algae will begin to create small duplicates of itself inside of the parent algae. After a while the parent will burst and let loose the daughter algae. Aside from daughter colony formation, algae also use sporulation as a means to reproduce. Sporulation is used by algae more than daughter colony formation. It consists of the parent algae creating reproductive cells within the cell walls. The zoospores(reproductive cells) escape from the parent cell and attach themselves to surface where they turn into filaments. Algae also reproduce sexually and the combination of gametes identifies isogamy and heterogamy,which are two classes of sexual reproduction. Isogametes are gametes that are alike in size and shape. In isogamy, the gametes that are being combined do not have any physical peculiarity amid male and female gametes. The isogametes side with each other's flagellar extremities touching and after a short time they form one, immobile diploid zygote. Unlike isogamy, heterogamy is the uniting of a male gamete and a female gamete. The algae produces sperm in large amounts and the egg cell that is produced is bigger than the sperm and unlike the sperm cell, it is immobile.