Jean-Pascal Berge

Reassessment of lipid composition of the diatom, Skeletonema costatum

In the present work, we questioned the natural or artifactual origin of the large amounts of free fatty acids recovered in lipids from the diatom Skeletonema costatum. Using rapid cell harvest and a very drastic method to extract the lipids, we demonstrated that these lipid patterns rich in free fatty acids were relevant to the degradation of complex lipids. A revised lipid composition of S. costatum is given which differs from those previously described by the absence of free fatty acids, while the proportion of polar lipids is substantially increased. Membrane lipids are mostly represented and storage lipids are less abundant, since we analysed the cells during their exponential growth phase. However, the fatty acid composition is in agreement with previous data. Polyunsaturated fatty acids (PUFA) consist essentially of 20: 5 to3, 16: 3 04 and 16: 4 to 1, while 16: 1 m7 is the main monounsaturated FA. This confirms that, with regard to its lipid composition, the diatom, S. costatum, provides a good diet for molluscs, particularly through its high proportion of eJ3 PUFA. Using this extraction procedure, sterols were found to be identical to previous results but a new compound, a 18:1 fatty alcohol, was detected. The consequences of this reassessement on the lipid compositions of diatoms so far published and their application to the lipid diet of mollusc larvae in aquaculture are discussed.

Antibacterial activity of the marine diatom Skeletonema costatum against aquacultural pathogens

The antibacterial activity of Skeletonema costatum (Grev.) Cleve against aquacultural bacteria was examined. The active compounds, partly purified from an organic phase, were tested against some pathogens of shellfish or fish. The growth of Listonella (=Vibrio) anguillarum and several species of the genus Vibrio appeared to be inhibited.

Screening of Marine Algal Extracts for Anti-settlement Activities against Microalgae and Macroalgae

The ban on the use of TBT-based antifouling paints for boats under 25 m in length has lead to a search for new non-toxic antifoulants. One of the most promising alternative technologies to heavy metal based antifouling paint is the development of antifouling coatings whose active ingredients are naturally occurring compounds from marine organisms. This is based on the principle that marine organisms also face the problem of the presence of epibionts on their own surfaces. In this study, the antifouling activity of a series of aqueous, ethanolic and dichloromethane extracts from thirty algae from the North East Atlantic coast was investigated. The extracts were tested in laboratory assays against species representative of two major groups of fouling organisms, viz . macroalgae and microalgae. The activity of several extracts was comparable to that of heavy metals and biocides (such as TBTO and CuSO 4 ) currently used in antifouling paints and their lack of toxicity with respect to the larvae of oysters and sea urchins suggests a potential for novel active ingredients.

Enzymatic hydrolysis of cuttlefish (Sepia officinalis) and sardine (Sardina pilchardus) viscera using commercial proteases: effects on lipid distribution and amino acid composition.

Total lipid and phospholipid recovery as well as amino acid quality and composition from cuttlefish (Sepia officinalis) and sardine (Sardina pilchardus) were compared. Enzymatic hydrolyses were performed using the three proteases Protamex, Alcalase, and Flavourzyme by the pH-stat method (24 h, pH 8, 50 degrees C). Three fractions were generated: an insoluble sludge, a soluble aqueous phase, and an oily phase. For each fraction, lipids, phospholipids, and proteins were quantified. Quantitative and qualitative analyses of the raw material and hydrolysates were performed. The degree of hydrolysis (DH) for cuttlefish viscera was 3.2% using Protamex, 6.8% using Flavourzyme, and 7% using Alcalase. DH for sardine viscera was 1.9% (using Flavourzyme), 3.1% (using Protamex) and 3.3% (using Alcalase). Dry matter yields of all hydrolysis reactions increased in the aqueous phases. Protein recovery following hydrolysis ranged from 57.2% to 64.3% for cuttlefish and 57.4% to 61.2% for sardine. Tissue disruption following protease treatment increased lipid extractability, leading to higher total lipid content after hydrolysis. At least 80% of the lipids quantified in the raw material were distributed in the liquid phases for both substrates. The hydrolysed lipids were richer in phospholipids than in the lipids extracted by classical chemical extraction, especially after Flavourzyme hydrolysis for cuttlefish and Alcalase hydrolysis for sardine. The total amino acid content differed according to the substrate and the enzyme used. However, regardless of the raw material or the protease used, hydrolysis increased the level of essential amino acids in the hydrolysates, thereby increasing their potential nutritional value for feed products.

Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties

BACKGROUND Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin-like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene-related peptide (CGRP)-like peptides demonstrated an increase in CGRP-like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin-converting enzyme (ACE)-1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION Fractionation of an FPH using membrane separation, with a molecular weight cut-off adapted to the peptide composition, may provide an effective means to concentrate CGRP-like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut-off of the membrane only, as is currently done in the literature.

Metabolites from the Sponge-Associated Bacterium Pseudomonas Species

Abstract: Quinolones and a phosphatidyl glyceride were isolated from the sponge-associated bacterial strain Pseudomonas sp. Structures were elucidated by spectroscopic analysis and chemical transformations.

How Enzymes May Be Helpful for Upgrading Fish By-Products: Enhancement of Fat Extraction

Abstract The beneficial health effects of consumption of marine foods, in general, and of marine oils, in particular, are well recognized. Fish by-products constitute valuable sources of components, such as lipids for human consumption, and liver and roe from large cod (Gadus morhua)are currently exploited. This paper presents a new approach for extracting lipids from several cod by-products by using a pre-hydrolysis step with large spectrum proteases in order to disrupt tissues and cell membranes. Yields extraction for total lipids, phospholipids, EPA and DHA are compared to those obtained by organic extraction.

Recovery of valuable soluble compounds from washing waters generated during small fatty pelagic surimi processing by membrane processes

Abstract This work focuses on the treatment of washing waters coming from surimi manufacturing using ultrafiltration technology at a laboratory scale. Four membrane materials (poly‐ether sulfone, polyacrilonytrile, poly vinylidene fluoride and regenerated cellulose) and 5 Molecular Weight Cut‐Off (from 3 to 100 kDa) have been studied at bench laboratory scale using the pilot Rayflow® 100, commercialised by Rhodia Orelis. The investigation deals with the ability for membranes to offer a high retention of biochemical compounds (proteins and lipids). Results obtained during adsorption tests showed that the regenerated cellulose material seems to be the most appropriate with regards to pore size reduction due to the protein‐adsorption. During the ultrafiltration of the washing water, the regenerated cellulose material leads to the best results, followed by the polyacrylonitrile and poly‐vinylidene fluoride materials. Poor results were obtained with poly‐ether sulfone membrane. Compared to the other materials, the regenerated cellulose is the easiest to regenerate, with minimal cleaning water and no chemical treatment necessary. Biochemical characterization of the fractions generated during the ultrafiltration with the polyacrilonytrile, poly vinylidene fluoride and regenerated cellulose membranes showed that all the membranes provided a high recovery rate of the lipids and proteins. The 10 kDa regenerated cellulose membrane had the highest performance and was further evaluated. With such a treatment, the chemical oxygen demand was reduced by 75%. By performing hydrolysis followed by a centrifugation, biochemical composition of the sludge and liquid fraction were modified, producing an insoluble fraction containing fats and few proteins and a soluble fraction containing proteins and few fats. The sludge, initially insoluble, was mainly solubilized during hydrolysis, and lipids and peptides were concentrated by ultrafiltration.

Combined Effects of Nitrogen Concentration and Seasonal Changes on the Production of Lipids in Nannochloropsis oculata

Instead of sole nutrient starvation to boost algal lipid production, we addressed nutrient limitation at two different seasons (autumn and spring) during outdoor cultivation in flat panel photobioreactors. Lipid accumulation, biomass and lipid productivity and changes in fatty acid composition of Nannochloropsis oculata were investigated under nitrogen (N) limitation (nitrate:phosphate N:P 5, N:P 2.5 molar ratio). N. oculata was able to maintain a high biomass productivity under N-limitation compared to N-sufficiency (N:P 20) at both seasons, which in spring resulted in nearly double lipid productivity under N-limited conditions (0.21 g L−1 day−1) compared to N-sufficiency (0.11 g L−1 day−1). Saturated and monounsaturated fatty acids increased from 76% to nearly 90% of total fatty acids in N-limited cultures. Higher biomass and lipid productivity in spring could, partly, be explained by higher irradiance, partly by greater harvesting rate (~30%). Our results indicate the potential for the production of algal high value products (i.e., polyunsaturated fatty acids) during both N-sufficiency and N-limitation. To meet the sustainability challenges of algal biomass production, we propose a dual-system process: Closed photobioreactors producing biomass for high value products and inoculum for larger raceway ponds recycling waste/exhaust streams to produce bulk chemicals for fuel, feed and industrial material.

Proteolysis of shrimp by-products (Peaneus monodon) from Madagascar Proteólisis de derivados de langostino (Peaneus monodon) de Madagascar

To generate and recover elements from shrimp heads, proteolysis was performed with commercial acidic or alkaline proteases for 22 h. The resulting phases were characterized for protein and lipid content and amino acid composition while the molecular profiles of soluble peptides were established. Whatever the protease used, more than the half of the initial dry matter was found into aqueous phase including most of the proteins while lipids were found to remain insoluble. Hydrolysates were mainly constituted by small peptides (>80% below 1000 Da) with up to 14–15 amino acids identified. Moreover, all the hydrolyses have led to an increase of the amount of essential amino acids into the hydrolysates, including lysine. Thus, such proteolysis of shrimp heads can increase their potential nutritional value (small peptides with high content in essential amino acids) while allowing the concentration of lipids into insoluble phase and a partial demineralisation of the exoskeleton. Para crear y recuperar elementos de las cabezas de langostino se llevó a cabo una proteólisis con proteasas ácidas y alcalinas comerciales durante 22 horas. Las fases resultantes se caracterizaron por contenido proteico y lípidico, composición de aminoácidos, mientras los perfiles moleculares de péptidos solubles fueron establecidos. Cualquiera fuese la proteólisis, más de la mitad de la materia seca inicial se encontró en fase acuosa, incluida la mayor parte de las proteínas, mientras los lípidos resultaron mantenerse insolubles. Los hidrolizatos estuvieron constituidos principalmente por pequeños péptidos (>80% por debajo 1000 Da) con hasta 14–15 aminoácidos identificados. Es más, todas las hidrólisis llevaron a un incremento de la cantidad de aminoácidos esenciales en los hidrolizatos, incluido lisina. Así, dicha proteólisis de cabezas de langostino puede incrementar de este modo su valor nutricional potencial (pequeños péptidos con un alto contenido en aminoácidos esenciales) mientras permite la concentración de lípidos en pase soluble y una desmineralización parcial de esqueleto externo.