Search

Saline and hypersaline environments such as natural saline seas, lakes, coastal lagoons, marine salterns, deserts, saline soils, etc. are considered extreme habitats for microbial life. They harbor halophiles as well as halotolerant microorganisms growing in the absence of salt and in the same time tolerant to relatively high salt concentrations. Halophilic microorganisms suggest many advantages for biotechnological exploration like relatively short time course of fermentations, lack of pathogenicity and the production of stable biomolecules, such as exopolysaccharides (EPS), under the extreme conditions of the most industrial processes. The aim of this chapter is to present a summary of the status of the research about the structures and the biosynthesis of exopolysaccharides by halophilic microorganisms, including medium-released and biofilm embedded polysaccharides. Moreover, relationships between the structure and the function of the exopolysaccharides and their possible biotechnological and industrial applications, are discussed.

The exopolysaccharides (EPSs) belong to the family of organic thickeners or alternative hydrocolloids of microbial origin (Cerning 1990). EPS are produced by bacteria, microalgae and by yeasts and molds to protect the cell from unfavorable, limiting or toxic conditions and from the external environment (Sutherland, 1972). Due to their chemical structures that offers beneficial bioactive functions, biocompatibility, and biodegradability, EPSs are used in chemical, food, pharmaceutical, cosmetics, packaging industries, agriculture, and medicine, as adhesives, absorbents, lubricants and cosmetic (Mata et al., 2006). For the EPS production at industrial scale, microbial processes are faster than traditional EPSs extraction with highest production yields. Currently a wide range of agricultural by-products and waste materials are used as components of the substrates for the production of EPS like sugarcane vinasse.

The exopolysaccharide (EPS) production by psychrophilic Antarctic yeast Sporobolomyces salmonicolor AL1 reached the maximum yield in medium containing sucrose (50 g/L) and diammonium sulfate (2.5 g/L) after a 5-d fermentation (5.64 g/L) at 22 °C, the dynamic viscosity of the culture broth reaching (after 5 d) 15.4 mPa s. EPS showed a mannan-like structure and high molar mass, and did not affect cellular viability and proliferation of murine macrophages. It exhibited also a protective effect against the toxic activity of Avarol.

A new polysaccharide with a high molecular weight (greater than 1 x 106 Da) was extracted and characterized from the peels of Passiflora liguralis (granadilla) fruits. Chemical composition of the biopolymer, performed by using a high pressure anion exchange-pulsed amperometric detector (HPAE-PAD), showed the presence of six different sugar residues: xylose, glucose, galactose, galactosamine, an unknown component, and fucose in the relative ratio of 1:0.5:0.2:0.06:0.05:trace. The optical rotation of this xyloglucan was [alpha](D)(25) degrees C = -186.42 (concentration of 1.4 mg/mL of H(2)O), and the viscosity was dependent on the concentration and pH, showing a maximum value of 1.4 eta at a concentration of 3% in distilled water and a maximum value of 7.0 eta in citrate buffer solution. Thermogravimetric analysis indicated that this biopolymer was very stable at high temperatures, showing a degradation temperature at 280 degrees C. The characterization of the polysaccharide was also investigated by spectroscopic methods (1H NMR and IR) pointing out the complexity of this biopolymer and the presence of sugar residues in alpha-manno, alpha-gluco-galacto, and beta-gluco-galacto configurations. The formation of a biodegradable film using this novel xyloglucan was reported, and the anticytotoxic activity of the polysaccharide was studied in a brine shrimp bioassay. Considerable antioxidant activity (Trolox equivalent antioxidant capacity (TEAC) value of 0.32 microM/mg fresh product) was noted in the lipophilic extracts of Passiflora liguralis fruits, indicating, in this fruit, an alternative source of bioactive compounds.

There is a great interest on study of extreme microorganisms because of their special characteristics in biotechnology. Particularly, halophilic microorganisms which live in saline environments throughout of their different adaptation mechanisms produce metabolites with great potential. Some of its biomolecules has been studied and applied in industrial processes, such as exopolyssaccharides, carotenoid pigments, bacteriorhodopsin etc. beside certain enzymes especially hydrolases (pectinases, amylases, proteases, lipases, etc.) are important. Recent researches on halophilic microorganisms and their biomolecules have increased around the world. Saline environments such as saline lakes or saline soils are excellent sources for isolation of halophilic microorganisms. However, few saline environments have been studied in depth in order to evaluate the special characteristics of halophilic biomolecules. In this review, the importance of halophilic microorganisms for biotechnological industries, methods for their isolation; techniques for physiological, taxonomical and molecular characterization have been highlighted so as to establish them as important source for enzyme production.

Three exopolysaccharides, EPS(1), EPS(2), and EPS(3), were isolated from suspension-cultured cells of tomato (Lycopersicon esculentum, var. San Marzano). The partial primary structures were determined on the basis of spectroscopic analyses. EPS(2) was a heteropolysaccharide with a tetrasaccharide repeating unit constituted by sugars having one residue in alpha-manno, one residue in beta-manno, and two different residues in beta-gluco/galacto configurations. EPS(3) was a heteropolysaccharide with a pentasaccharide repeating unit with sugars having three residues in alpha-manno, one residue in alpha-gluco/galacto, and one residue in beta-gluco/galacto configurations. The anticytotoxic activities of exopolysaccharides were tested in a brine shrimp bioassay.

In this work we investigated the ability of four extremophilic bacteria from Archaea and Bacteria domains to resist to space environment by exposing them to extreme conditions of temperature, UV radiation, desiccation coupled to low pressure generated in a Mars' conditions simulator. All the investigated extremophilic strains (namely Sulfolobus solfataricus, Haloterrigena hispanica, Thermotoga neapolitana and Geobacillus thermantarcticus) showed a good resistance to the simulation of the temperature variation in the space; on the other hand irradiation with UV at 254nm affected only slightly the growth of H. hispanica, G. thermantarcticus and S. solfataricus; finally exposition to Mars simulated condition showed that H. hispanica and G. thermantarcticus were resistant to desiccation and low pressure.

The binding of the 14 C-labeled herbicide thidiazimin (SN 124 085) to membrane-bound protoporphyrinogen oxidase (protox) from corn ( Zea mays ) and its displacement by the diphenyl ethers acifluorfen (AF), acifluorfen methyl, and oxyfluorfen were examined and compared to their inhibitory activity on protox. SN 124 085 is a potent inhibitor of protox comparable to oxyfluorfen and acifluorfen methyl, all with I 50 values in the nanomolar range. SN 124 085 is a competitive inhibitor with respect to the substrate protoporphyrinogen having an inhibition constant ( K i ) of 0.25 n M . Using 14 C-labeled SN 124 085, a binding constant K b of 0.26 n M was obtained. The ability of acifluorfen, acifluorfen methyl, and oxyfluorfen to strictly compete with SN 124 085 was used to examine the binding affinity of the diphenyl ether-type herbicides to protox. All three inhibitors displaced SN 124 085 competitively, acifluorfen methyl being most effective. Secondary plots of the binding of SN 124 085 with different concentrations of the competing nonlabeled inhibitor present yielded the binding constant of the latter. While the potent herbicides acifluorfen methyl and oxyfluorfen showed K b constants below 1 n M , the binding affinity of AF was found to be 10-fold lower, according to its lower inhibitory activity. Binding constants of all inhibitors were found to be similar to their inhibition constant, demonstrating displacement studies as a reliable technique to determine the binding affinity of protox inhibitors.

ABSTR. 402

abstr.83

Results of optimization of an excimer laser-induced plasma x-ray source for projection lithography in the range λ = 13–15 nm are reported. A conversion efficiency of >0.7% in 2% BW has been achieved with high-Z target materials. Two methods of reducing contamination of optical elements by target debris have been tested: usage of a thin target layer (for Ta 1 μm was found to be optimal) and of a heavy buffer gas. The effect of the use of Ta-tape target and Kr buffer gas has been measured by determining the reflectivity of a Mo-Si multilayer sample after 10 5 shots.

abstr.93

Polysaccharides from solid wastes of the processing tomato industry (Lycopersicon esculentum 'Hybrid Rome') were extracted using a simple and rapid method, purified and chemically characterised. The yield of biopolymers represented 7.5 % of lyophilised biomass. The polysaccharide showed a complex structure. On the basis of NMR data, the repeating unit was constituted by eight monosaccharides, three of them with an ? manno configuration, four residues with an ? gluco-galacto configuration and one residue showing a ? gluco-galacto configuration. The specific viscosity (?) of the biopolymer, performed at different values of concentration and pH, showed a dependence with respect to the concentration, and the maximum value of viscosity was obtained at pH 3.0.

Food canning industries represent an important area of the Italian economy, in particular the industrial conversion of tomatoes into tomato purée, pulp and tomato minced from seed-firms. One of the main problems of the food industry is the management of waste and their conversion into products of higher value. Modern technologies eco-compatible, promote the use of food waste to obtain biopolymers that can be re-used in the same sector of the raw materials. We have studied the adjustment of extraction and purification procedures of wood-cellulose material coming from products and by-products of farm and food production, and finally their physical-chemical characterization. The achievement of biodegradable and thermoplastic materials by using chemical and enzymatic processes from polysaccharides is also reported. The realization of three and more manufactured articles, for example flowerpots or rigid packing vases, film for agriculture use and ensiling film will be in progress.

ABSTR.96

review article

Lipophilic compounds contained in tomato can prevent cardiovascular diseases by modulating the atherogenic processes in vascular endothelium mediated by oxidized low-density lipoproteins (LDLs). We investigated the effects of lycopene on the metabolism of platelet-activating factor (PAF) and its much less biologically active acyl analog, acyl-PAF, known to prevent LDL oxidation. Lycopene, or lycopene in association with alpha-tocopherol, or whole tomato lipophilic extracts (containing more than 80% lycopene) were used in experiments in which endothelial cells (ECs) are known to synthesize PAF following H(2)O(2)-induced oxidative stress. The results indicated that in each case H(2)O(2)-stimulated PAF biosynthesis in ECs, which is catalyzed by acetyl-CoA acetyltransferase (AT), appeared strongly inhibited. However, acyl-PAF biosynthesis, which also occurs through the PAF-dependent transacetylase (TA), was significantly increased by lycopene only when it was in association with alpha-tocopherol or with the minor compounds present in the whole lipophilic tomato extract. These findings suggest that alpha-tocopherol or lipophilic compounds present in tomato juice potentiate the effects of lycopene on the modulation of PAF and acyl-PAF biosynthesis in ECs during oxidative stress.

The optimization of controllers for closed-loop position control of electrical driven hydraulic servo valves is very costly, the plant is highly nonlinear, and consequently requires a complex nonlinear controller. Moreover, the assessment of the achieved performance has to be considered for a large set of different operating situations and is consequently usually performed manually. This paper describes the design of a fuzzy performance-index that, with the help of an evolutionary algorithm, enables automation of the optimization process.

ABSTR. L32

ABSTR.10B