Determination Of Lipid Content Research Articles

Biomass and lipid productivities of marine microalgae isolated from the Persian Gulf and the Qeshm Island

Abstract In this work, the screening of 147 microalgal strains from the Persian Gulf and the Qeshm Island (Iran) were done in order to choose the best ones, in terms of growth (biomass) rate and lipid content for biodiesel production. A methodology, combining experiments in lab-scale and pilot plant (open pond) used to produce and evaluate biomass and lipid productivity is presented for the systematic investigation of the potential of different microalgae species. The culture conditions, including photo flux (180 μE m −2 s −1 ), photoperiod (12 h light/dark), temperature (25 °C), pH (≈8), air (carbon dioxide) and growth medium, were kept constant for all experiments. Microalgae were screened in two stages using optical density (for evaluation of biomass concentration) and Nile red and gas chromatography (for determination of lipid content and fatty acid fractions). In general, maximum specific growth rate and the maximum biomass productivity were obtained after 8–12-day culture. Nannochloropsis sp. and Neochloris sp. were selected from the marine microalgal culture collection, due to their high biomass (50 and 21.7 g L −1 , respectively) and oil content (52% and 46%, respectively). If the purpose is to produce biodiesel only from one species, Nannochloropsis sp. presented the most adequate fatty acid profile, namely linolenic and other polyunsaturated fatty acids. However, the microalgae Chlorella sp. can also be used if associated with other microalgal oils. In addition, selected strains could be potent candidates for commercial production in the open pond culture.

Feasibility of Spectroscopic Characterization of Algal Lipids: Chemometric Correlation of NIR and FTIR Spectra with Exogenous Lipids in Algal Biomass

A large number of algal biofuels projects rely on a lipid screening technique for selecting a particular algal strain with which to work. We have developed a multivariate calibration model for predicting the levels of spiked neutral and polar lipids in microalgae, based on infrared (both near-infrared (NIR) and Fourier transform infrared (FTIR)) spectroscopy. The advantage of an infrared spectroscopic technique over traditional chemical methods is the direct, fast, and non-destructive nature of the screening method. This calibration model provides a fast and high-throughput method for determining lipid content, providing an alternative to laborious traditional wet chemical methods. We present data of a study based on nine levels of exogenous lipid spikes (between 1% and 3% (w/w)) of trilaurin as a triglyceride and phosphatidylcholine as a phospholipid model compound in lyophilized algal biomass. We used a chemometric approach to corrrelate the main spectral changes upon increasing phospholipid and triglyceride content in algal biomass collected from single species. A multivariate partial least squares (PLS) calibration model was built and improved upon with the addition of multiple species to the dataset. Our results show that NIR and FTIR spectra of biomass from four species can be used to accurately predict the levels of exogenously added lipids. It appears that the cross-species verification of the predictions is more accurate with the NIR models (R 2 = 0.969 and 0.951 and RMECV = 0.182 and 0.227% for trilaurin and phosphatidylcholine spike respectively), compared with FTIR (R 2 = 0.907 and 0.464 and RMECV = 0.302 and 0.767% for trilaurin and phosphatidylcholine spike, respectively). A fast high-throughput spectroscopic lipid fingerprinting method can be applied in a multitude of screening efforts that are ongoing in the microalgal research community.

Production of bio-fuels (hydrogen and lipids) through a photofermentation process

The purple non-sulfur photosynthetic bacteria Rhodopseudomonas palustris (strain 42OL) was investigated for a co-production of both bio-H 2 and biodiesel (lipids). The investigation was carried out using malic and glutamic acids in a fed-batch cultivation system under continuous irradiances of 36, 56, 75, 151, 320, 500, and 803 W m −2. Boltzmann’s sigmoidal regression model was used to determine growth kinetic parameters during hydrogen photoevolution. The upper limit of volumetric hydrogen photoevolution was 15.5 ± 0.9 ml l −1 h −1. During the entire cultivation period (408 h), the highest average hydrogen production rate (HPR av) of 11.1 ± 3.1 ml l −1 h −1 was achieved at an irradiance of 320 W m −2. Biomasses stored at the end of each experimental set were analyzed in order to determine lipid content, which ranged from a minimum of 22 ± 1% to a maximum of 39 ± 2% of biomass dry weight.

Biochemical determination of lipid content in hepatic steatosis by the Soxtec method

To establish a quantitative method to measure the amount of lipids. The livers of 53 male Wistar rats (225 g) with different degrees of hepatic steatosis were studied. This model of hepatic steatosis was based on a high carbohydrate, fat-free modified diet. Biopsies were classified into four grades depending on fat accumulation, using the Kleiner and Brunt classification. Total fat was studied by the Soxtec method (Soxtec 2050 Auto Fat Extraction System), and agreement between both assays was assessed by calculating the kappa coefficient. According to the histological classification, 38% of rats presented grade 0, 21% grade 1, 22% grade 2 and 20% grade 3. The amount of fat per 100 g tissue was 2.60 +/- 0.64 g for grade 0, 3.87 +/- 1.59 g for grade 1, 5.82 +/- 1.37 g for grade 2 and 8.68 +/- 2.30 g for grade 3. Statistically significant differences were found between the mean values for each of the histological grades (P < 0.05). The correlation for the quantification of fat in the liver between both assays was moderate (kappa = 0.60). The biochemical quantification of fat in liver tissue by the Soxtec method was correlated with the histological classification, although the agreement between the two tests was only moderate.

Rapid quantitation of lipid in microalgae by time-domain nuclear magnetic resonance

A specific strain of Chlorella protothecoides has been studied in heterotrophic fermentation for increasing cell growth rate and lipid content for biodiesel production. For optimizing the process of fermentation to reduce costs of alga-based biodiesel production, rapid determination of lipid content in microalgal cells is critical. Nile Red (NR) staining and time-domain nuclear magnetic resonance (TD-NMR) have been investigated to quantitate the lipid content in C. protothecoides. Both methods were found feasible and simpler than gravimetric methods that are commonly employed. The TD-NMR method showed better agreement ( R 2 = 0.9973) with the measured values from lipid extraction experiments than the NR staining method ( R 2 = 0.9067). Additionally, the smaller standard deviations of the samples (≤ 0.36) analyzed by TD-NMR revealed that the method is accurate and reproducible. The application of TD-NMR for lipid quantitation in C. protothecoides opens up the possibility of determining lipid content in algal fermentation precisely and quickly.

Determination of lipid contents of meals of children with food allergies

Determination of lipid contents of meals of children with food allergies

Lipid Analysis by near Infrared Spectroscopy to Evaluate Inhibitory Effects of Swine Waste Compost on Plant Growth

The lipid content of swine manure decreases during the process of composting, and inhibitory effects of compost on root growth in germination tests are strongly correlated to lipid content. Therefore, we tested whether the determination of the lipid content of swine waste compost by near infrared (NIR) spectroscopy provided a measure by which the degree of inhibition of plant growth by immature compost could be predicted. Reflectance spectra of untreated compost samples, as well as freeze-dried and milled samples, were taken using a scanning monochromator. Second derivative spectra from 700 nm to 2500 nm and multiple regression analysis were used to develop calibration equations for lipid content and moisture. A pronounced absorption peak of lipid was found at 2310 nm, attributable to the absorption bands of the CH2 stretching–bending combination. However, calibration equations containing this absorption band were inappropriate for lipid determination, because sawdust and rice husk, which were added to the compost, influenced the spectra in this band. The standard error of prediction ( SEP) of the best calibrations for lipids in dry and untreated samples was 6.0 g kg−1 and 3.2 g kg−1, while the ratios of the standard deviation and the range in the prediction set to SEP (RPD and RER) were 5.5 and 2.8, and 13.5 and 5.0, respectively. The main wavelengths of these calibration equations were 1700 nm for dry samples and 1764 nm for untreated samples, which were attributed to the absorption bands of the CH2 stretching first overtone. In conclusion, the determination of lipid content in dry compost samples by NIR spectroscopy provided an indirect estimate of the maturity of swine waste compost. Moreover, NIR spectroscopy was found useful for the rough assessment of the maturity of untreated swine waste compost.

Peroxisome Proliferator-activated Receptor (PPAR)-2 Controls Adipocyte Differentiation and Adipose Tissue Function through the Regulation of the Activity of the Retinoid X Receptor/PPARγ Heterodimer

Peroxisome Proliferator-activated Receptor (PPAR)-2 Controls Adipocyte Differentiation and Adipose Tissue Function through the Regulation of the Activity of the Retinoid X Receptor/PPARγ Heterodimer

Impairment of lipid storage by cadmium in the European eel ( Anguilla anguilla)

Because European silver eels ( Anguilla anguilla) fast during their reproductive migration to the Sargasso Sea, the successful completion of their unusual life cycle depends on quantity of lipids stored beforehand. These lipids are mainly accumulated during the growth phase stage of the animals, called yellow eel, as triglycerides in muscle. They are then catabolized to provide sufficient energy to enable migration, gonad maturation and spawning. In the laboratory, we investigated the possible impact of cadmium on the lipid storage efficiency of yellow eels in order to evaluate the possible contribution of this pollutant to the reported decline of European eel populations. Eels were exposed to dissolved cadmium at nominal concentrations of 0 and 5 μg L −1 for 1 month. Cd toxicity was then examined by studying the activity and expression level of several enzymes involved in liver lipolysis and lipogenesis and by determining lipid content in muscle. Contaminated eels showed a lower body weight growth with a lower efficiency of lipid storage compared to controls. Using two complementary approaches, genetic and enzymatic, it was possible to conclude that this impairment is mainly explained by an increased utilisation of triglycerides since cadmium contamination did not trigger a reduced fatty acid synthesis. These observations suggest an increased fat consumption in presence of cadmium, which could compromise successful reproduction.

LIPID ANALYSIS OF FILLETS FROM GIANT GRENADIER (ALBATROSSIA PECTORALIS), ARROW‐TOOTH FLOUNDER (ATHERESTHES STOMIAS), PACIFIC COD (GADUS MACROCEPHALUS) AND WALLEYE POLLOCK (THERAGRA CHALCOGRAMMA)

ABSTRACT In Alaska, walleye pollock (WP [Theragra chalcogramma]) and Pacific cod (PC [Gadus macrocephalus]) are harvested in large amounts. There are also large biomasses of arrow‐tooth flounder (ATF [Atheresthes stomias]) and giant grenadier (GG [Albatrossia pectoralis]) available in Alaskan waters; however, these fish are underutilized. The objective of this study was to determine lipid content, lipid class distribution and fatty acid (FA) profiles of fillets from these four fish species. Fat content and percent triacylglycerides (TAG) in ATF was significantly higher than in other species, and percent phospholipids (PL) was lower (P &lt; 0.05). PC had the highest levels of omega‐3 (ω‐3) FA, whereas ATF had the lowest. The ratio of ω‐3/omega‐6 (ω‐6) FA was significantly higher in ATF than in other species. Percent polyunsaturated and saturated FA's were equivalent in ATF; however, other species showed at least twice as much polyunsaturated FA as saturated FA. This study provided comparisons of the lipid characteristics in the two most abundant white fish harvested in Alaska and two other abundant but underutilized species.

Ultrasound velocity measurement to determine lipid content in salmon muscle; the effects of myosepta

Currently, there are no reliable and inexpensive non-destructive techniques available to measure the composition of fish during processing. In this paper, ultrasound pulse transit time measurement techniques are applied to aquaculture to measure the intramuscular fat in salmon fillets. Measurements on samples of salmon white muscle are described and the results of velocity measurements on a group of samples of varying fat content are reported. Differences from theory are considered in the light of the muscle structure. Results suggest that it is possible to group the velocities into “high fat”, “medium fat” and “low fat” categories but not to predict fat content with great accuracy because of inhomogeneity in the structure of the muscle. Ray-tracing techniques were used to model the propagation velocity of a wavefront travelling through a single salmon sample. The model provided an insight into how variations in fat content, myoseptum thickness and myosepta configuration affect measured velocity.

Seasonal Variation in Reproductive Traits of the Oviparous Water Snake, Natrix maura, in the Ebro Delta of Northeastern Spain

Seasonal Variation in Reproductive Traits of the Oviparous Water Snake, Natrix maura, in the Ebro Delta of Northeastern Spain

Evaluation and comparison of the CEM rapid extraction method with official standard methods for the determination of lipid content in fillets of farmed Atlantic salmon ( Salmo salar)

The CEM rapid extraction method for lipid content determination was compared with official standard methods and was found to give accurate results for individual samples, taking approximately 8 min per sample. The study involved the lipid analysis of 47 white muscle samples from six fillets of farmed Atlantic salmon, using both the CEM and the Soxhlet method, in order to evaluate the performance of the former. Nine samples from each fillet with variable lipid content, ranging from 2.0% to 25.4%, were analysed. The comparison of the CEM with the Soxhlet method showed that the CEM lipid values were significantly linearly correlated ( r 2=0.993, P<0.001), but were consistently lower than those of the standard by a factor of 0.37%. This difference was found to be more distinct in samples with lipid content below 10%. It is concluded that the CEM method is an effective rapid analysis method for the determination of lipid content in salmon fillets under commercial conditions for the routine monitoring of muscle lipid. For research purposes, it may be necessary to add a correction factor (0.59% for levels below 10% lipid and 0.27% above 10%) if direct comparisons with Soxhlet results are required.

Failure of Total Body Electrical Conductivity to Predict Lipid Content of Brook Trout

Abstract We found that a noninvasive procedure that used total body electrical conductivity (TOBEC) failed to estimate lean mass and whole body lipid content of brook trout Salvelinus fontinalis. We explored two approaches using TOBEC, the inverse-regression approach, in which lipid mass is predicted from the relationship between TOBEC, and lean mass and the multiple-regression approach, in which lipid is predicted directly from TOBEC and morphological measurements. With the inverse-regression approach, TOBEC was a good estimator of lean mass but did not predict lipid mass. With the multiple-regression approach, length and mass alone explained lipid mass best; TOBEC did not add significant explanatory power. We conclude that TOBEC was not a sensitive or cost-effective tool for determining lipid content of brook trout and urge caution in its use with other fish species.

Comparative study of methodologies for the analysis of PCDDs and PDCFs in powdered full-fat milk. PCB, PCDD and PCDF levels in commercial samples from Spain

Feasibility of two different extraction methods involving solid-liquid extraction and Soxhlet extraction, previously used for the determination of lipid contents and PCB levels on powdered full-fat milk, are now examined for simultaneous PCDD/F analysis. The results of this study are consistent with those found for PCBs. The solid-liquid procedure provides the most efficient extraction of both labelled spiked and endogenous PCDD/Fs with the lowest variability. The average recoveries were 101% (R.S.D.=6.9%) for 13C 12,-2,3,7,8-TCDD and 95% (R.S.D.= 11%) for 13C 12-1,2,3,4,7,8-HxCDD. The R.S.D.s for endogenous 2,3,7,8-PCDD/Fs were in the 9.3–25% range. In addition, this methodology simplified the subsequent clean-up step as it allowed a semi-selective extraction of the apolar lipids from the milk. The proposed method was applied to simultaneous PCB and PCDD/F analyses in different brands of powdered full-fat milks commercially available in Spain. In all cases, very similar PCB and PCDD/F levels were found. Differences among batches from the same manufacturer were even lower. The total i-TEQ average for PCDDs and PCDFs OCDFs in the 22 powdered full-fat milk samples analysed was l.87 pg/g fat basis. This value was similar to those found in cow's milk from other European countries.

Seasonal lipid contents of Antarctic microarthropods

A technique for the accurate determination of lipid content of very small quantities of biological tissue was applied to two Antarctic oribatid mites,Alaskozetes antarcticus andHalozetes belgicae, and a collembolan,Cryptopygus antarcticus. Analysis of monthly samples of the three species, collected between November 1989 and March 1991, revealed little evidence of any seasonal pattern of lipid deposition or use. MaleAlaskozetes were the only exception, showing very low lipid levels for a short period of the austral summer, followed by rapid deposition before the onset of winter. Mean lipid contents of the three species over the study period were 10–15% of mean dry weight. There was evidence of a seasonal pattern of egg formation and oviposition in bothAlaskozetes andHalozetes, but this was not reflected in the observed lipid levels. Feeding activity was mostly restricted to the summer months (November–March); a temporary resumption of feeding in winter (late August 1990) was followed by an increase in lipid content in both sexes ofAlaskozetes.

Addition of lipid to total parenteral nutrition prevents hepatic steatosis in rats by lowering the portal venous insulin/glucagon ratio.

Hepatic steatosis in rats is associated with an infusion of excessive carbohydrate calories. Previous work from this laboratory suggested that this is associated with an elevated portal insulin/glucagon molar ratio (I/G) and is reversed by parenteral glucagon administration. Although hepatic steatosis is not related to essential fatty acid deficiency, addition of lipid to total parenteral nutrition (TPN) has been reported as being protective against the development of hepatic steatosis. Therefore, we propose that lipid may exert its salutary effect via an alteration of the I/G ratio. To test this hypothesis, adult rats (seven per group) received internal jugular catheters: group 1, saline (3 mL/h) plus chow ad libitum; group 2, 25% dextrose base TPN; group 3, 17% dextrose base TPN + 2.5% lipid; group 4, 25% dextrose base TPN + 2.5% lipid. At 7 days, portal and peripheral venous blood was drawn for insulin and glucagon radioimmunoassay and liver function tests; livers were removed for histology and lipid content determination. Panlobular vacuolization, on histology, and lipid content were excessive in group 2, and the portal I/G was increased because of elevated portal insulin. In contrast, portal venous insulin and I/G did not increase, and hepatic steatosis was absent in groups 3 and 4. The results suggest that the addition of lipid to TPN in rats decreases the portal insulin level and lowers the portal I/G, and thereby prevents hepatic steatosis.

Lipid-ovary indices in food-limited Daphnia

The amount of lipid carried by a zooplankton individual is highly variable. Various lines of evidence have suggested that the nutritional condition of animals could be ascertained via the determination of lipid content. However, few studies have been conducted where the lipid levels of animals of known condition have been measured. Here, we report on the lipid index and combined lipid-ovary index values of Daphnia obrusa reared on foods made up of varying quantity and quality of a unialgal (Scenedesmus acutus) diet. Lipid levels differed in different food types. However, in no cases were these indices positively correlated to growth rate, such as would be necessary if one were to use them to diagnose food limitation in the field. Thus, we urge caution in the utilization of either the lipid or lipid-ovary index until more is known about the role of fatty acids in the diets of these animals.

Magnetic resonance morphological, chemical shift and flow imaging in peripheral vascular disease

We have used magnetic resonance imaging to study the aorto-iliac region in 13 patients with peripheral disease. Five healthy volunteers were studied for comparison. Magnetic resonance spin-echo imaging, chemical shift imaging to determine lipid content of atheroma, phase-shift velocity mapping and quantitative flow studies were obtained and the findings compared with radiological angiograms. The velocity profiles study showed an increased velocity at the site of a stenosis in eight patients who had iliac artery disease. Quantitative flow measurements made in both iliac arteries and the aorta in five patients and five volunteers showed a flow ratio in both iliac arteries less than 0.85 in patients with a stenosis of one iliac artery and a ratio greater than 0.85 in the volunteers. In one patient studied before and after angioplasty, flow improved post-angioplasty. The flow curve showed a characteristic distortion in diseased vessels compared with healthy vessels. In the chemical shift images of aortic atheroma five were classified as fibrous and three were lipid rich. This preliminary study showed the potential of magnetic resonance to assess non-invasively the morphology, composition and the haemodynamic significance of atheroma. This could be important in the study of the progression of peripheral vascular disease and its response to pharmacological and surgical intervention and in the planning treatment of lesions.

Addition of l-glutamine to total parenteral nutrition and its effects on portal insulin and glucagon and the development of hepatic steatosis in rats

Infusion of total parenteral nutrition (TPN) with excess carbohydrate calories leads to hepatic steatosis in rats and is associated with an elevated portal insulin/glucagon molar ratio. Previously we have shown that adding glucagon to TPN prevents and reverses hepatic steatosis in rats, possibly by increasing hepatic lipid export. It has been reported that steatosis is eliminated in rats by the addition of l-glutamine to TPN. In this study, we examined the effect of glutamine on portal insulin and glucagon levels and the development of hepatic steatosis. Adult rats ( n = 19) received internal jugular catheters: Group 1 ( n = 6), saline (3 cc/hr) and chow ad libitum; Group 2 ( n = 7), 25% dextrose base TPN; Group 3 ( n = 6), 25% dextrose base TPN with 2% glutamine. The infusion rate of TPN was 1.2 cc/100 g body wt/hr. Daily nitrogen balance was determined and at 7 days, portal venous blood was drawn for insulin and glucagon radioimmunoassay, livers were removed for histology and lipid content determination, and the small intestines were removed for mucosal protein and DNA content determination. Panlobular vacuolization of the hepatocytes was noted on histology in Group 2 (TPN) while Group 1 (chow) and Group 3 (TPN + glutamine) showed normal liver morphology. Hepatic lipid content was significantly elevated in Group 2 ( P < 0.05). The portal insulin/glucagon molar ratio was increased because of excessive portal venous insulin in Group 2 (TPN). In contrast, portal glucagon was significantly elevated while the insulin/glucagon ratio and hepatic lipid content did not increase above control levels in the glutamine-supplemented Group 3 rats. The results suggest that addition of l-glutamine to hypertonic dextrose TPN prevents the development of hepatic steatosis, possibly by stimulating glucagon secretion and thus lowering the portal insulin/glucagon ratio and increasing hepatic lipid export.