Strategy for improving extracellular lipolytic activities by a novel thermotolerant Staphylococcus sp. strain

<p>Abstract</p> <p>Background</p> <p>Extracellular bacterial lipases received much attention for their substrate specificity and their ability to function under extreme environments (pH, temperature...). Many staphylococci produced lipases which were released into the culture medium. Reports of extracellular thermostable lipases from <it>Staphylococcus </it>sp. and active in alkaline conditions are not previously described.</p> <p>Results</p> <p>This study focused on novel strategies to increase extracellular lipolytic enzyme production by a novel <it>Staphylococcus </it>sp. strain ESW. The microorganism needed neutral or alkaline pH values between 7.0 and 12.0 for growth. For pH values outside this range, cell growth seemed to be significantly inhibited. <it>Staphylococcus </it>sp. culture was able to grow within a wide temperature range (from 30 to 55°C). The presence of oils in the culture medium leaded to improvements in cells growth and lipolytic enzyme activity. On the other hand, although chemical surfactants leaded to an almost complete inhibition of growth and lipolytic enzyme production, their addition along the culture could affect the location of the enzyme. In addition, our results showed that this novel <it>Staphylococcus </it>sp. strain produced biosurfactants simultaneously with lipolytic activity, when soapstock (The main co-product of the vegetable oil refining industry), was used as the sole carbon source.</p> <p>Conclusion</p> <p>A simultaneous biosurfactant and extracellular lipolytic enzymes produced bacterial strain with potential application in soap stock treatment</p

A newly high alkaline lipase: an ideal choice for application in detergent formulations

<p>Abstract</p> <p>Background</p> <p>Bacterial lipases received much attention for their substrate specificity and their ability to function in extreme environments (pH, temperature...). Many staphylococci produced lipases which were released into the culture medium. Reports of thermostable lipases from <it>Staphylococcus </it>sp. and active in alkaline conditions are not previously described.</p> <p>Results</p> <p>A newly soil-isolated <it>Staphylococcus </it>sp. strain ESW secretes an induced lipase in the culture medium. The effects of temperature, pH and various components in a detergent on the activity and stability of <it>Staphylococcus </it>sp. lipase (SL1) were studied in a preliminary evaluation for use in detergent formulation solutions. The enzyme was highly active over a wide range of pH from 9.0 to 13.0, with an optimum at pH 12.0. The relative activity at pH 13.0 was about 60% of that obtained at pH 12.0. It exhibited maximal activity at 60°C. This novel lipase, showed extreme stability towards non-ionic and anionic surfactants after pre-incubation for 1 h at 40°C, and relative stability towards oxidizing agents. Additionally, the crude enzyme showed excellent stability and compatibility with various commercial solid and liquid detergents.</p> <p>Conclusions</p> <p>These properties added to the high activity in high alkaline pH make this novel lipase an ideal choice for application in detergent formulations.</p

Production, bleaching and characterization of pulp from Stipa tenacissima

Alfa grass pulping was successfully performed in hydro-organic acid medium under mild conditions (107°C, atmospheric pressure, cooking time: 3 h). Use of an acetic acid/formic acid/water mixture as pulping liquor was perfectly suitable for selective isolation of pulp, lignin, and hemicelluloses. The unbleached pulp obtained in good yield was first delignified by peroxyacids in organic acid medium and then bleached with hydrogen peroxide in a basic medium to give pulp offering good physico-chemical and mechanical characteristics

Deciphering the Biological Activities of Dunaliella sp. Aqueous Extract from Stressed Conditions on Breast Cancer: from in Vitro to in Vivo Investigations

International audienceIn order to harness local resources to improve well-being and human health, we aim in this study to investigate if the microalgae Dunaliella sp. isolated from the Tunisian coastal zone possesses any anticancer activity. Dunaliella sp. was cultured under normal (DSC) or stressed (DSS) conditions and extracted using different procedures. The biological activity assessment was performed on the Triple Negative Breast Cancer (TNBC) using 4T1 murine cells as a model. Results indicate that: (i) aqueous extract was the most cytotoxic compared to ethanolic and hydroalcoholic extracts; (ii) DSS activity was superior to that of DSC. DSS extracts induced apoptosis rather than necrosis, as evidenced by DNA fragmentation, PARP-1 cleavage and caspase-3 activation. Evaluation in an orthotopic TNBC model validated the anticancer activity in vivo. Intratumoral injection of DSS extract resulted in reduced tumor growth and an enhanced immune system activation. On the transcriptional side, the expression level of the immunosuppressive enzyme Arg-1 was decreased, as well as those of NOS-2 and COX-2 genes. These results suggest a potential anticancer activity of Tunisian Dunaliella sp. deserving further attention

Flow cytometry assay to evaluate lipid production by the marine microalga Tetraselmis sp. using a two stage process

International audienceTetraselmis sp. strain MD-01, a microalga isolated from the Tunisian marine coast, has been studied for autotrophic lipids production with two stage process. This strategy was conducted for maximum cells production under moderated conditions (2.12 g L−1), followed by cultivation under stressed conditions to induce lipid synthesis. High irradiance (300 μmol m−2 s−1) and nitrogen depletion (S mode) showed better carotenoids accumulation and lower chlorophylls content in microalgae compared to those obtained in biomass cultivated under high irradiance (Sg mode). This two-stage strategy allowed to increase of lipid content in cells cultivated in Sg and S modes from 18% DW (stage I) to 50 and 61.5% DW (stage II), respectively, with an increase of saturated and long chain fatty acids levels. Based on fluorometry analyses, an increase of lipids in Nile-Red stained cells and a decrease of chlorophylls auto-fluorescence under stressed conditions were shown. From spectral data, the lipids: amide I ratio obtained from S mode was 2.17 and 4.45 times higher than that from Sg mode and control conditions, respectively. These results revealed the potential of Tetraselmis strain MD-01 for biodiesel production

Protective Role of Spirulina platensis against Bifenthrin-Induced Reprotoxicity in Adult Male Mice by Reversing Expression of Altered Histological, Biochemical, and Molecular Markers Including MicroRNAs

International audienceThe potential reprotoxicity of bifenthrin remains unclear if only the common clinical indicators of reproductive disease are examined. The present study aimed to investigate the efficacy of Spirulina platensis, a microalga rich in antioxidant compounds, against bifenthrin-induced testicular oxidative damage in male mice. At the first, we demonstrate that administration of bifenthrin resulted in a decline of testosterone level and in deterioration of sperm quality that was correlated with significant transcription changes of some specific mRNA and microRNA involved in cholesterol transport, testosterone synthesis, and spermatogenesis. At the biochemical level, we found that oxidative stress was obvious in the bifenthrin group, as evidenced by increase in malondialdehyde (MDA), protein carbonyls (PCO), reactive oxygen species (ROS), and nitrite oxide (NO) that was correlated with activation of genes related to mitochondrial apoptotic signal pathways. We then brought, for the first time to our knowledge, solid and complete experimental evidences that administration of mice with Spirulina extract was sufficient to protect against deleterious effects BF in testicular tissues by abrogating the change in antioxidant enzyme activities; the increase in MDA, PCO, and NO concentrations; and the altered expression level of miRNA and mRNA involved in spermatogenesis. We finally demonstrate that Spirulina restores the production of testosterone in mice as well as epididymal sperm viability and motility. These results suggest a potential antitoxic activity of Tunisian Spirulina deserving further attention

Carotenoids Overproduction in Dunaliella Sp.: Transcriptional Changes and New Insights through Lycopene β Cyclase Regulation

Dunaliella is a green microalga known for its ability to produce high levels of carotenoids under well-defined growing conditions. Molecular responses to the simultaneous effect of increasing salinity, light intensity and decrease of nitrogen availability were investigated in terms of their effect on different metabolic pathways (isoprenoids synthesis, glycolysis, carbohydrate use, etc.) by following the transcriptional regulation of enolase (ENO), 1-deoxy-D-xylulose 5-phosphate synthase (DXS), lycopene &beta;-cyclase (LCYB), carotene globule protein (CGP), chloroplast-localized heat shock protein (HSP70), and chloroplast ribulose phosphate-3-epimerase (RPE) genes. The intracellular production of carotenoid was increased five times in stressed Dunaliella cells compared to those grown in an unstressed condition. At transcriptional levels, ENO implicated in glycolysis, and revealing about polysaccharides degradation, showed a two-stage response during the first 72 h. Genes directly involved in &beta;-carotene accumulation, namely, CGP and LCYB, revealed the most important increase by about 54 and 10 folds, respectively. In silico sequence analysis, along with 3D modeling studies, were performed to identify possible posttranslational modifications of CGP and LCYB proteins. Our results described, for the first time, their probable regulation by sumoylation covalent attachment as well as the presence of expressed SUMO (small ubiquitin-related modifier) protein in Dunaliella sp

Cyanobacteria as source of marine bioactive compounds: Molecular specific detection based on Δ9 desaturase gene

The blue-green microalga, Arthrospira sp., isolated from the sea of Kssour Essef in Mahdia (Tunisia), was purified and then identified both morphologically and genetically based on 16S rRNA gene sequence. Following physicochemical analysis, the prokaryotic microalga tested represented a competitive source of pigments and showed a considerable rate in protein (64%) which was confirmed by FTIR measurement. The lipid content (4%) was quantified by the gravimetric method and the intracellular lipid bodies were detected with the Nile red staining. Using gas chromatography coupled with flame ionization detector, the fatty acid profile revealed the presence of 27.4% and 32.88% of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs), respectively. Given the richness of the isolated microalga in unsaturated fatty acids, we have developed a SYBR Green real time PCR method for the specific identification of Arthrospira sp. Delta 9 desaturase gene. This current method will be of great value for carrying out high-throughput studies like cloning, heterologous expression and structure-function relationship analysis

Structural Analysis of Alfa Grass (<i>Stipa tenacissima</i> L.) Lignin Obtained by Acetic Acid/Formic Acid Delignification

Alfa grass lignin obtained by the acetic acid/formic acid/water CIMV pulping process was characterized by FTIR and ¹H, ¹³C–¹H 2D HSQC, and ³¹P NMR spectroscopies. Lignin samples purified by further dissolution/precipitation or basic hydrolysis steps were also analyzed. The CIMV alfa lignin is a mixture of low molar mass compounds (<i>M</i>_n = 1500 g/mol) of <b>SGH</b> type with β-O-4 ether bonds as the major interunit linkage. The crude lignin contains fatty acids and residual polysaccharides. It also contains large amounts of acetate and hydroxycinnamates, mostly in the γ-position of β-O-4 interunit linkages. Although partial acetylation induced by the process cannot be excluded, the absence of aromatic acetates and acetylated polysaccharides in crude lignin demonstrates the mildness of the process. By combining smooth alkaline hydrolysis and dissolution/precipitation steps to the CIMV pulping, it is possible to produce a purified lignin with a composition and a structure quite analogous to that of the native polymer in the plant