Potential of local microalgae cultures for biodiesel production and for disease management -

Abstract

Microalgae are prokaryotic or eukaryotic photosynthetic plant like microorganisms that have received a lot of attention in the last 50 years due to the increased demand on environmentally safe alternatives for diesel production. The taxonomy of these microalgae relied on microscopic and chemical analysis, however, due to difficulties and inaccuracy of these methods, molecular identification is gaining importance. Several primary and secondary markers have been developed targeting different genomic regions. In this study 25 local isolates, unialgal or mixed algal blooms, were isolated and cultured in either seawater or fresh water. Twelve isolates were identified to the genus level and twelve to the species level using primers targeting the LSU, ITS and Tuf A region. The following genera and-or species were identified: Acutodesmus obliquus, Amphora sp., Chlorella sp., Chloromonas sp., Cyanobacterium aponinum, Micractinium reisseri, Microcoleus sp., Neochloris conjuncta, Scenedesmus sp., Scherffelia dubia, Tetraselmis marina,Tetraselmis sp., and Tetraselmis striata. The ability of microalgae to accumulate high levels of lipids under certain culture conditions motivated researchers to explore the possibilities of using them as a renewable biosource to produce biodiesel. The lipid content was determined for 21 microalgal isolates. Under our experimental conditions, total lipid content varied between 5percent DW in Tetraselmis marina and 21.85percent DW in PS isolate. However, higher lipid content can be induced through manipulation of culturing conditions by imposition of environmental and nutritional stress. Three of the local microalgae isolates contained about 50percent protein. Microalgae are also significant sources for bioactive secondary metabolites. The antimycotic activity of methanolic and water extracts from five microalgae isolates was tested in-vitro against five different plant pathogenic fungi. None of the isolates showed an antimycotic activity, but better sporulation and growth was recorded in the methanolic and cr