Microbiological resolution of chiral arylethyl carbinols by Nocardia corallina

Whole cells of Nocardia corallina B-276 oxidized enantioselectively racemates of arylethyl carbinols, at 0.5 mM, to give ketones in yields from 4 to 97% (w/w) and the unreacted alcohols showing enantiomeric excess ranging from 5 to > 99%. The configuration of the resulting alcohol is (R).     

Observations of de novo clones of cytogentically aberrant cells in primary fibroblast cell strains from phenotypically normal women.

In a recent study of chromosome breakage frequencies in 36 primary fibroblast cell strains derived from skin from 10 phenotypically normal women, we observed seven different clones of cells having consistent chromosomal abnormalities. Five of the stem lines were noted in cultures from "control" women and two in fibroblasts from women taking oral contraceptives. We observed aneuploid clones as well as stem lines bearing structural abnormalities (e.g., translocation, inversions). The various aberrant clones were found in cultures ranging in age from 41 to 144 days and comprised varying percentages of the cell populations ranging from 0.8% to virtually 100%. The possible evolution in culture of clones of cells having aberrant karyotypes should be considered in interpreting findings from fibroblast cultures initiated for clinical evaluation.     

Starch biosynthesis: sucrose as a substrate for the synthesis of a highly branched component found in 12 varieties of starches

D-[14C]glucose was incorporated into starch when 12 varieties of starch granules were incubated with [14C]sucrose. Digestion of the 14C-labeled starches with porcine pancreatic alpha amylase showed that a high percentage (16.1-84.1%) of the synthesized starch gave a relatively high molecular weight alpha-limit dextrin. Hydrolysis of the 12 varieties of starch granules by alpha amylase, without sucrose treatment, also gave an alpha-limit dextrin, ranging in amounts from 0.51% (w/w) for amylomaize-7 starch to 8.47% (w/w) for rice starch. These alpha-limit dextrins had relatively high molecular weights, 2.47 kDa for amylomaize-7 starch to 5.75 kDa for waxy maize starch, and a high degree of alpha-(1-->6) branching, ranging from 15.6% for rice starch to 41.1% for shoti starch. ADPGlc and UDPGlc did not synthesize a significant amount (1-2%) of the branched component, suggesting that sucrose is the probable substrate for the in vivo synthesis of the component and that sucrose is not first converted into a nucleotide-glucose diphosphate intermediate.     

Stoned olive pomace fermentation with Pleurotus species and its evaluation as a possible animal feed

The use of stoned olive pomace (SOP) as an unconventional feedstuff for livestock is limited by its inherently low crude protein (CP) content and by the presence of anti-nutritional compounds such as phenols. Aim of this study was to assess whether solid-state fermentation of SOP with selective lignin-degrading fungi might ameliorate nutritional properties of the waste. Incubation of SOP, mixed (25%, w/w) with various conventional feedstuffs (i.e., wheat bran, wheat middlings, barley grains, crimson clover, wheat flour shorts and field beans), with Pleurotus ostreatus and Pleurotus pulmonarius led to significant CP increases, ranging from 7 to 29%, and marked removal (from ca. 50–90%) of phenols after 6 weeks. Both species, however, led to moderate delignification associated with significant consumption of hemicelluloses. Consequently, no improvements of both organic matter digestibility (OMD) and net energy of SOP–feedstuff mixtures occurred after the fungal colonization.     

Thermal stability of human haemoglobin in the presence of sarcosine and sorbitol

Sarcosine and sorbitol at 10–30% (w/w) stabilized haemoglobin from human erythrocytes to thermal denaturation. At 65?°C, the protein's half life was increased from 0.85 to 50 min in 30% sarcosine and to 24 min in 30% sorbitol. A kinetic analysis based on the Lumry-Eyring mechanism of inactivation showed that the denaturation process can be described by a second-order rate expression with an apparent activation energy ranging from 56 to 87 kcal mol^?1.     

Comparative investigation of primary and tertiary endodermal cell walls isolated from the roots of five monocotyledoneous species: chemical composition in relation to fine structure

The chemical composition of isolated endodermal cell walls from the roots of the five monocotyledoneous species Monstera deliciosa Liebm., Iris germanica L., Allium cepa L., Aspidistra elatior Bl. and Agapanthus africanus (L.) Hoffmgg. was determined. Endodermal cell walls isolated from aerial roots of M. deliciosa were in their primary developmental state (Casparian bands). They contained large amounts of lignin (6.5% w/w) and only traces of suberin (0.5% w/w). Endodermal cell walls isolated from the other four species were in their tertiary developmental state. Lignin was still the more abundant cell wall polymer with amounts ranging from 3.8% (w/w, A. cepa) to 4.5% (w/w, I. germanica). However, compared to endodermal cell walls in their primary state of development (Casparian bands), tertiary endodermal cell walls contained significantly higher amounts of suberin, ranging from 1.8% (w/w, I. germanica) to 3.0% (w/w, A. africanus). Thus, chemical characterization of endodermal cell walls from five different species revealed that lignin was the dominant cell wall polymer in the Casparian band of M. deliciosa, whereas tertiary endodermal cell walls contained, in addition to lignin, increasing amounts of suberin (I. germanica, A. cepa, A. elatior and A. africanus). Besides the two biopolymers lignin and suberin, cell wall carbohydrates in the range of between 40 and 60% were also quantified. The sum of all cell wall compounds investigated by gas chromatography resulted in a recovery of 50–80% of the dry weight of the isolated cell wall material. Quantitative chromatographic results in combination with microscopic studies are consistent with the existence of a distinct suberin lamella and lignified tertiary wall deposits. From these data it can be concluded that the barrier properties of the endodermis towards the apoplastic transport of ions and water will increase from primary to tertiary endodermal cell walls due to their increasing amounts of suberin. Received: 23 August 1997 / Accepted: 28 January 1998     

Physicochemical behavior of homogeneous series of acetylated chitosans in aqueous solution: role of various structural parameters

Physicochemical properties of four different homogeneous series of chitosans with degrees of acetylation (DA) and weight-average degrees of polymerization (DP(w)) ranging from 0 to 70% and 650 to 2600, respectively, were characterized in an ammonium acetate buffer (pH 4.5). Then, the intrinsic viscosity ([eta](0)), the root-mean-square z-average of the gyration radius (R(G,z)), and the second virial coefficient (A(2)) were studied by viscometry and static light scattering. The conformation of chitosan, according to DA and DP(w), was highlighted through the variations of alpha and nu parameters, deduced from the scale laws [eta](0) = K(w)and R(G,z) = K', respectively, and the total persistence length (L(p,tot)). In relation with the different behaviors of chitosan in solution, the conformation varied according to two distinct domains versus DA with a transition range in between. Then, (i) for DA < 25%, chitosan exhibited a flexible conformation; (ii) a transition domain for 25 < DA < 50%, where the chitosan conformation became slightly stiffer and, (iii) for DA > 50%, on increasing DP(w) and DA, the participation of the excluded volume effect became preponderant and counterbalanced the depletion of the chains by steric effects and long-distance interactions. It was also highlighted that below and beyond a critical DP(w,c) (ranging from 1 300 to 1 800 for DAs from 70 to 0%, respectively) the flexibility of chitosan chains markedly increased then decreased (for DA > 50%) or became more or less constant (DA < 50%). All the conformations of chitosan with regards to DA and DP(w) were described in terms of short-distance interactions and excluded volume effect.     

Reconstitution of Human Casein Micelle and Its Properties

Human casein micelles were reconstituted from isolated κ- and β-caseins and calcium ions. Micelle formation was recognized in the presence of calcium chloride even at the low concentration of 5mM. At pH levels ranging from 5.5 to 8.0, the re-formed micelles were quite stable so that precipitation of β-casein was not observed. The large micelles were constituted by a higher ratio of β-casein to κ-casein (16:1 by weight) than the small micelles (3: 1). The κ-casein in the small micelles contained carbohydrates to about 43% (w/w) in the molecule, whereas that in the large micelles was only about 25%. When the casein micelles were re-formed from κ-easein and fractionated β-casein components, the extent of phosphorylation of the β-casein component was found to influence the micelle formation; i.e., the β-casein component with no phosphate (the 0-P form) was disadvantageous to form micelles, but the component with 5 phosphates (the 5-P form) formed micelles most easily.     

Factors affecting emulsion stability and quality of oil recovered from enzyme-assisted aqueous extraction of soybeans

The objectives of the present study were to assess how the stability of the emulsion recovered from aqueous extraction processing of soybeans was affected by characteristics of the starting material and extraction and demulsification conditions. Adding endopeptidase Protex 6L during enzyme-assisted aqueous extraction processing (EAEP) of extruded soybean flakes was vital to obtaining emulsions that were easily demulsified with enzymes. Adding salt (up to 1.5 mM NaCl or MgCl₂) during extraction and storing extruded flakes before extraction at 4 and 30 °C for up to 3 months did not affect the stabilities of emulsions recovered from EAEP of soy flour, flakes and extruded flakes. After demulsification, highest free oil yield was obtained with EAEP of extruded flakes, followed by flour and then flakes. The same protease used for the extraction step was used to demulsify the EAEP cream emulsion from extruded full-fat soy flakes at concentrations ranging from 0.03% to 2.50% w/w, incubation times ranging from 2 to 90 min, and temperatures of 25, 50 or 65 °C. Highest free oil recoveries were achieved at high enzyme concentrations, mild temperatures, and short incubation times. Both the nature of enzyme (i.e., protease and phospholipase), added alone or as a cocktail, concentration of enzymes (0.5% vs. 2.5%) and incubation time (1 vs. 3 h), use during the extraction step, and nature of enzyme added for demulsifying affected free oil yield. The free oil recovered from EAEP of extruded flakes contained less phosphorus compared with conventional hexane-extracted oil. The present study identified conditions rendering the emulsion less stable, which is critical to increasing free oil yield recovered during EAEP of soybeans, an environmentally friendly alternative processing method to hexane extraction.     

Aminolysis of 2-hydroxy esters catalyzed by Candida antarctica lipase

Candida antarctica lipase catalyzed the aminolysis of 2-hydroxy esters with amines in organic solvents to yield the corresponding 2-hydroxy amides. The reactions proceeded at 28–30 °C in dioxane for 6 h with 3 mM substrates with yields ranging between 45% (w/w) (for branched substrates) to 88% (w/w) (for linear substrates). Although the reaction was not enantioselective, because of its simplicity it represents an alternative method for the synthesis of functionalised amides.     

THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN COLOR AND SALT CONCENTRATIONS IN CHICKEN FLAVORED BROTHS

Taste panelists evaluated the effect of color on salt perception in chicken flavored samples using magnitude estimation. Samples were colored to simulate commercial chicken broth. Five color intensities were added to 5 NaCl concentrations ranging from 0.34 to 0.66% (w/v). Color had no influence on salt perception. Panelists were able to perceive color differences among samples (P <0.001) and these were correlated with the objective color function cot⁻¹ (a/b) calculated from the L,a,b values obtained from the Gardner XL-23. Overall flavor preference was evaluated by a taste panel using the technique of magnitude estimation. NaCl concentrations ranged from 0.52 to 0.80% (w/v). Overall flavor preference was unaffected by color. A reduction in NaCl concentration from 0.80% (w/v) to 0.52% (a 35% reduction) did not alter flavor preference. A 50 member consumer panel using a paired comparison test found no difference in flavor preference between an uncolored sample containing 0.80% (w/v) NaCl and a colored sample containing 0.72% (w/v) NaCl.     

Localization of benzyl glucosinolate and thioglucosidase in Carica papaya fruit

Macerated papaya seeds and pulp contained benzyl isothiocyanate, produced by the enzymatic hydrolysis of benzyl glucosinolate by thioglucosidase. The substrate and enzyme were localized in different areas. In mature papaya seeds, thioglucosidase was found in sarcotestae but not in endosperms, while the reverse was true for benzyl glucosinolate, which constituted more than 6% (w/w) of the endosperms. Both the enzyme and substrate were present in embryos and the amount of the latter was 3·9% (w/w). In immature papaya pulp, benzyl glucosinolate was localized principally, if not exclusively, in the latex, ranging from 7·3 to 11·6% of the dry wt of latex fluid. No thioglucosidase activity was found in papaya latex. The possible significance of the localization of this enzyme-substrate system and aspects concerning functions of papaya latex are discussed.     

Comparative testing of disinfectants using proposed European surface test methods

A surface test method for disinfectants currently under development as a standard European test method is described. The test involves determining the number of viable organisms recoverable from a contaminated stainless steel surface before and after application of disinfectant. Evaluation of a range of disinfectant agents and products currently used in the UK indicated that products at recommended use concentrations produced log reductions in viable count ranging from < 1.0 to > 6.4 (i.e. no detectable survivors) after a 5 min contact period against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecium and Candida albicans. Increased activity was observed by increasing the disinfectant contact time to 30 min. Addition of 3% w/v albumin to the test suspension used to inoculate surfaces caused a substantial reduction in activity.     

Establishment and Growth of Embryogenic Suspension Cultures of Ocotea catharinensis Mez. (Lauraceae)

The focus of this study was to test the effects of 2,4-D, sucrose, culture media and initial inocula on the development of embryogenic suspension cultures of Ocotea catharinensis Mez. (Lauraceae). Suspension cultures were established in half-strength MS medium supplemented with 2% (w/v) sucrose either in the absence or in the presence of 2.2 μM 2,4-D, when higher cell viability was achieved. Under this culture condition the maximum fresh weight increase occurred in the fourth week. The cultures were yellow and consisted of a mixture of highly cytoplasmic single cells and small cell aggregates (<0.25 mm). The best proportion of inoculum per volume of medium for suspension culture development was 5% (w/w). Suspension cultures consisting of somatic embryos at the globular and cotyledonary stages (structures ranging from 1 to 3 mm) were successfully established on half-strength MS supplemented with 2% (w/w) sucrose through repetitive embryogenesis from the desiccated mature somatic embryos used as initial inoculum. The failure to initiate liquid cultures from non-desiccated mature somatic embryos was overcome by pre-treatment with air desiccation and reduction of the water content to 6.1 g H₂O g⁻¹ dry weight.     

Influence of xylan on the enzymatic hydrolysis of steam‐pretreated corn stover and hybrid poplar

The focus of this study was to alter the xylan content of corn stover and poplar using SO₂‐catalyzed steam pretreatment to determine the effect on subsequent hydrolysis by commercial cellulase preparations supplemented with or without xylanases. Steam pretreated solids with xylan contents ranging from ～1 to 19% (w/w) were produced. Higher xylan contents and improved hemicellulose recoveries were obtained with solids pretreated at lower severities or without SO₂‐addition prior to pretreatment. The pretreated solids with low xylan content (<4% (w/w)) were characterized by fast and complete cellulose to glucose conversion when utilizing cellulases. Commercial cellulases required xylanase supplementation for effective hydrolysis of pretreated substrates containing higher amounts of xylan. It was apparent that the xylan content influenced both the enzyme requirements for hydrolysis and the recovery of sugars during the pretreatment process. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Poly(ethylene glycol)-induced and temperature-dependent phase separation in fluid binary phospholipid membranes.

Exclusion of the strongly hygroscopic polymer, poly(ethylene glycol) (PEG), from the surface of phosphatidylcholine liposomes results in an osmotic imbalance between the hydration layer of the liposome surface and the bulk polymer solution, thus causing a partial dehydration of the phospholipid polar headgroups. PEG (average molecular weight of 6000 and in concentrations ranging from 5 to 20%, w/w) was added to the outside of large unilamellar liposomes (LUVs). This leads to, in addition to the dehydration of the outer monolayer, an osmotically driven water outflow and shrinkage of liposomes. Under these conditions phase separation of the fluorescent lipid 1-palmitoyl-2[6-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine (PPDPC) embedded in various phosphatidylcholine matrices was observed, evident as an increase in the excimer-to-monomer fluorescence intensity ratio (IE/IM). Enhanced segregation of the fluorescent lipid was seen upon increasing and equal concentrations of PEG both inside and outside of the LUVs, revealing that osmotic gradient across the membrane is not required, and phase separation results from the dehydration of the lipid. Importantly, phase separation of PPDPC could be induced by PEG also in binary mixtures with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), for which temperature-induced phase segregation of the fluorescent lipid below Tm was otherwise not achieved. In the different lipid matrices the segregation of PPDPC caused by PEG was abolished above characteristic temperatures T0 well above their respective main phase transition temperatures Tm. For 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), DMPC, SOPC, and POPC, T0 was observed at approximately 50, 32, 24, and 20 degrees C, respectively. Notably, the observed phase separation of PPDPC cannot be accounted for the 1 degree C increase in Tm for DMPC or for the increase by 0.5 degrees C for DPPC observed in the presence of 20% (w/w) PEG. At a given PEG concentration maximal increase in IE/IM (correlating to the extent of segregation of PPDPC in the different lipid matrices) decreased in the sequence 1,2-dihexadecyl-sn-glycero-3-phosphocholine (DHPC) > DPPC > DMPC > SOPC > POPC, whereas no evidence for phase separation in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) LUV was observed (Lehtonen and Kinnunen, 1994, Biophys. J. 66: 1981-1990). Our results indicate that PEG-induced dehydration of liposomal membranes provides the driving force for the segregation of the pyrene lipid.(ABSTRACT TRUNCATED AT 400 WORDS)     

Structures and molecular dynamics of plant waxes

Waxes from the leaves of Fagus sylvatica L. (European beech tree) and Hordeum vulgare L. (barley) have been investigated using NMR, DSC, X-ray diffraction and gas chromatographic methods. The wax from Fagus sylvatica, consisting mainly of n-alkanals, n-alkanes and 1-alkanols, has chain-lengths ranging from 20 to 52 carbon atoms with an average chain-length of 30.5 carbon atoms. The X-ray results show that the wax is to a large extent ( 70%) amorphous. The wax from the leaves of Hordeum vulgare L., consisting mainly of n-alkanols, has chain-lengths ranging from 20 to 50 carbon atoms with an average chain-length of 27.4 carbon atoms. The wax is 52% crystalline. It seems that the structure of this wax differs from those of other plant waxes that have been investigated in that the longer chains bridge the amorphous zone between two adjacent layers of crystalline material, thus linking the two layers. This linking affects the melting point of the wax noticeably. The activation energies for the different molecular motions in these waxes have been extracted from the NMR spin-lattice relaxation time measurement. Correspondence to: E. C. Reynhardt     

High Frequency and Large Number of Polymorphic Microsatellites in Cultured Shrimp, <Emphasis Type="Italic">Penaeus (Litopenaeus) vannamei</Emphasis> [Crustacea:Decapoda]

A total of 1479 recombinant clones were obtained from a Sau3A-digested genomic library of Penaeus (Litopenaeus) vannamei and used for probe hybridization. Of the 251 clones that tested positive to one or more of the probes and were sequenced, 173 (69%) contained 573 simple sequence repeats, or microsatellites, with 3 or more repeats. The frequency of microsatellites with 3, 5, and 10 or more repeats was 1 in 0.94 kb, 1 in 2.78 kb, and 1 in 5.94 kb, respectively. To increase the number of polymorphic markers for mapping, 136 primer sets that flanked microsatellites containing single or multiple motifs with 3 or more repeats were designed and tested. Of the 136 primers, 93 (68.0%) were polymorphic in cultured shrimp, with polymorphism information content (PIC) values ranging from 0.195 to 0.873, and observed heterozygosities ranging from 10% to 100%. These markers are being used along with other markers to construct a linkage map for P. vannamei.     

Sambhar Salt Lake

The saline and alkaline brines from the Sambhar Salt Lake (SSL), both from the main lake and from the solar evaporation pans at Sambhar Salt Limited, Sambhar, Rajasthan, India, were studied with respect to their chemical composition and presence of red, extremely haloalkaliphilic archaebacteria. The brines had pH values of 9.5±0.2 and a total salt content ranging from 7% (w/v) to more than 30% (w/v). Sodium chloride, sodium carbonate, sodium bicarbonate and sodium sulphate were the principal salts present in these brines which lacked divalent cations (calcium and magnesium). Six strains of red, extremely haloalkaliphilic bacteria, designated SSL 1 to SSL 6, were isolated. All the isolates showed obligate requirements for sodium chloride (>15%, w/v) and high pH (>9.0). Magnesium ions were required in traces for maintaining morphological structure and pigmentation. All these strains possessed the diether core lipids, phosphatidylglycerol (PG), phosphatidylglycerophosphate (PGP), and bacterioruberins characteristic of halophilic archaebacteria. The strains were assigned to the newly proposed genus Natronobacterium.Part of the paper was presented by the authors at XIV International Congress of Microbiology 7–13 September 1986, Manchester, UK     

Effects of Pluronic F-68 on callus growth and protoplast plating efficiency of Solanum dulcamara

Summary The effects of the non-ionic surfactant, Pluronic F-68, on the growth of callus and protoplasts from Solanum dulcamara L. have been studied. Growth of callus was stimulated by addition of 0.1% (w/v) commercial grade Pluronic to culture medium, whereas lower concentrations (0.01% w/v) had no corresponding effect. In contrast, higher concentrations (1.0% w/v) of Pluronic inhibited callus growth. The mean plating efficiency of protoplasts grown at different densities (15 days after plating) was increased up to 26% following culture with 0.1% (w/v) Pluronic, while 0.01% (w/v) Pluronic was ineffective. Mean protoplast plating efficiency decreased by up to 32% following culture with 1.0% (w/v) Pluronic.