Microalgae offer a high potential for energetic lipid storage as well as high growth rates. They are therefore considered promising candidates for biofuel production, with the selection of high lipid-producing strains a major objective in projects on the development of this technology. We developed a mutation-selection method aimed at increasing microalgae neutral lipid productivity. A two step method, based on UVc irradiation followed by flow cytometry selection, was applied to a set of strains that had an initial high lipid content and improvement was assessed by means of Nile-red fluorescence measurements. The method was first tested on Isochrysis affinis galbana (T-Iso). Following a first round of mutation-selection, the total fatty acid content had not increased significantly, being 262 ± 21 mgTFA (gC)-1 for the wild type (WT) and 269 ± 49 mgTFA (gC)-1 for the selected population (S1M1). Conversely, fatty acid distribution among the lipid classes was affected by the process, resulting in a 20% increase for the fatty acids in the neutral lipids and a 40% decrease in the phospholipids. After a second mutation-selection step (S2M2), the total fatty acid content reached 409 ± 64 mgTFA (gC)-1 with a fatty acid distribution similar to the S1M1 population. Growth rate remained unaffected by the process, resulting in a 80% increase for neutral lipid productivity.

It is essential to have simple rapid methods for the determination of fatty acid structures. Traditionally, fatty acids are analysed by gas chromatography using their methyl ester derivatives (FAME). However, their corresponding mass spectra exhibit molecular ions but are usually devoid of ions indicative of structural features and, notably, the position of double bounds on the aliphatic chains [1]. In the most useful approach to structure determination, the carboxyl group is derivatised with a reagent containing a nitrogen atom. Recently, a convenient method for preparing picolinyl esters from intact lipids has been published [2]. However, some problems occurred in our laboratory when this method was used, leading to some modifications and optimisation. Thus, hexane and water have been added while sodium bicarbonate has been removed in order to lower contamination. Temperature and length of the reaction have then been optimised in order to get 100% derivatisation for different kinds of lipids (45 7C and 45 min for FAME). Finally, a comparison of the response factors has confirmed the better sensitivity of the picolinyl derivative against FAME (five times more).

A marine-related Trichoderma longibrachiatum strain isolated from mussels in a farming shellfish area was investigated for total lipid (TL) production, total lipid fatty acids (TLFA), and phospholipid fatty acids (PLFA). Fungal biomass was produced from two different marine-like culture ways, on agar surface and submerged fermentations (ASF and SmF, respectively), allowing useful comparisons. ASF produced a rather higher biomass amount than SmF with similar TL content. All fatty acids (FA), identified by gas chromatography-mass spectrometry (GC-MS), were ranged from 14 to 30 carbon atoms. Similar FA compositions were found in TL and phospholipids (PL) from biomasses obtained by both fermentation systems, including oleic (up to 15.3% of total FA mixture for SmF, and 33.9% for ASF), linoleic (46.1% for SmF, and 40.3% for ASF) and palmitic (28.1% for SmF, and 19.1% for ASF) acids as major components. Regarding the most common FA, lipid class and FA profiles observed did not show marked differences with those available for some Trichoderma terrestrial species. Some 2-hydroxylated FA and a rather unusual series of C 18 unsaturated conjugated FA (CFA) were identified. In addition, fungal biomass production by ASF was found as an easy to operate process, especially for further screenings of marine-derived fungi. #

If rays are traditionally fished for their caudal fins, the rest of the body is wasted, except part of the skin that can be transformed into leather. Liver oil of the ray, Himantura bleekeri, was characterized in terms of lipid class composition and fatty acid profile. Liver oil content was high and represented 54% of the liver weight (w/w). Neutral lipids were predominant (92%), major components being triacylglycerols (63%). Other neutral lipids identified were hydrocarbons, sterol esters, mono-and diacylglycerols, free fatty acids, sterols and glyceryl ethers. Polyunsaturated fatty acids of the n−3 series, namely eicosapentaenoic and docosahexaenoic acids, were high (4% and 16%, respectively). Cholesterol was the major component in the sterol fractions (free or esterified). Hydrocarbons were up to 30 carbons and squalene was present at the level of 22%. Thus, this liver oil proved to be an adequate source of n−3 fatty acids and other valuable lipidic compounds.

The gas chromatographic properties of four derivatives of fatty acids (FA), namely fatty acid methyl esters, picolinyl esters, N-acyl pyrrolidides and 4,4-dimethyloxazoline derivatives, which contain various structural features (double bonds, branching, hydroxyl group) in their acyl chains have been compared on a low-polarity capillary column with a mass spectrometer as detector. Temperature programming rates yielding the highest resolution were optimized for each derivative by means of computer-assisted column temperature optimization software. Indeed, the Drylab software represents a valuable assistance for estimating the optimum analysis conditions. Time and efforts required for such method development can greatly be reduced. Different parameters (derivatization procedure, total run time, resolution and response factor) are discussed. N-Acyl pyrrolidides and picolinyl esters appear quite powerful for structure elucidation of polyunsaturated FA by GC-MS, and both these types of FA derivatives can be very well separated on a low-polarity phase.