Microalgae heterotrophic production

In addition to applications as direct and indirect feeds mentioned above, the heterotrophic production of microalgae can potentially provide a cost-effective source of nutrient components, e.g. marine protein, PUFA or astaxanthin, that can be incorporated into formulated feeds for larval stages and beyond. Harel and Place (2004) provide more detail on the broad applications of heterotrophic production of marine algae for aquaculture. 

RUNNING J A, HUSS R J and OLSON p T (1994) Heterotrophic production of ascorbic acid by microalgae. Journal of Applied Phycology, 6, 99-104. 

Chlorella is a freshwater, unicellular green microalga that is widely used as a food supplement in Japan and around the world. Mass commercial cultivation of Chlorella for use as a health food supplement has taken place for over 35 years, with a more recent application in mariculture feed (Iwamoto, 2004). Many strains of Chlorella can be grown heterotrophically, allowing for production of a high-quality powder without contamination. Chlorella supplements are taken in the form of tablets, capsules, liquid, or as food additives. Claims for health benefits of Chlorella include improved immune function and improved control of hypertension, fibromyalgia, and ulcerative colitis (Halperin et al, 2003). 

Autotrophic microalgae as well as heterotrophic yeasts, bacteria, and fungi impH-cate limitations for a commerdal SCOs production process. An overview is hsted in Table 5.12. The main reasons are the costly downstream process of the SCOs and the high costs of carbon sources for heterotrophic microorganisms. 

Gao C, ZhaiY, DingY,Wu Q. Appbcation of sweet sorghum for biodiesel production by heterotrophic microalga Chlorella protothecoides. Appl Energy 2010 87 756. 

Perez-Garcia O, Escalante FME, de-Bashan LE, Bashan Y. Heterotrophic cultures of microalgae metabolism and potential products. Water Res 2011 45 11. 

Li, L., W. Du, D. Liu, L. Wang, and Z. Li. 2006. Lipase-Catalyzed Transesterification of Rapeseed Oils for Biodiesel Production with a Novel Organic Solvent as the Reaction Medium. Journal of Molecular Catalysis B Enzymatic 43 (l-4) 58-62 Li, X., H. Xu, and Q. Wu. 2007. Large-Scale Biodiesel Production from Microalga Chlorella Protothecoides through Heterotrophic Cultivation in Bioreactors. Biotechnology and Bioengineering 98 (4) 764-771. 

Microalgae are able to get energy from different metabolisms (Richmond and Qian 2004). In autotrophic metabolism, in the presence of light, organisms are able to convert CO2 and water into biomass. Already heterotrophic systems are a different approach to microalgal biomass production with elimination of light requirement and CO2 absorption. 

Li X, Xu H, Wu Q (2007) Large-scale biodiesel production from microalga Chlorella protothecoides through heterotrophic cultivation in bioreactors. Bioteehnol Bioeng 98... 

Wei A, Zhang X, Wei D, (Then G, Wu Q, Yang ST (2009) Effects of cassava starch hydrolysate on cell growth and lipid accumulation of the heterotrophic microalgae Chlorella protothecoides. J Ind Microbiol Biotechnol 36(11) 1383-1389. doi 10.1007/sl0295-(X)9-0624-x Wynn JP, Ratledge C (2005) Oils from microorganisms. In Shahidi F (ed) Bailey s industrial oil and fat products, vol 3, 6th edn, Edible oil and fat products specially oils and oil products. Wiley, Hoboken, pp 121-153... 

Xiong X, Wang X, Chen S (2012) Engineering of a xylose metabolic pathway in Rhodococcus strains. Appl Environ Microbiol 78(16) 5483-5491. doi 10.1128/AEM.08022-l 1 Xu H, Miao X, Wu Q (2006) High quality biodiesel production from a microalga Chlorella protothecoides by heterotrophic growth in fermenters. J Biotechnol 126(4) 499-507. doi 10. 1016/j.jbiotec.2006.05.002... 

---