Yeast extract stimulates production of glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma hubeiensis SY62

We improved the culture conditions for a biosurfactant producing yeast, Pseudozyma hubeiensis SY62. We found that yeast extract greatly stimulates MEL production. Furthermore, we demonstrated a highly efficient production of MELs in the improved medium by fed-batch cultivation. The final concentration of MELs reached 129 ± 8.2g/l for one week.     

Microbial conversion of glycerol into glycolipid biosurfactants, mannosylerythritol lipids, by a basidiomycete yeast, Pseudozyma antarctica JCM 10317(T)

Microbial conversion of glycerol into functional bio-based materials was investigated, aiming to facilitate the utilization of waste glycerol. A basidiomycete yeast, Pseudozyma antarctica JCM 10317, efficiently produced mannosylerythritol lipids (MELs) as glycolipid biosurfactants from glycerol. The amount of MEL yield reached 16.3 g l(-1) by intermittent feeding of glycerol.     

Isolation of Pseudozyma churashimaensis sp. nov., a novel ustilaginomycetous yeast species as a producer of glycolipid biosurfactants, mannosylerythritol lipids

An ustilaginomycetous anamorphic yeast species isolated from the leaves of Saccharum officinarum (sugarcane) in Okinawa, Japan, was identified as a novel Pseudozyma species based on morphological and physiological aspects and molecular taxonomic analysis using the D1/D2 domains of the large subunit (26S) rRNA gene and the internal transcribed spacer 1 (ITS1)-5.8S-ITS2 regions. The name Pseudozyma churashimaensis sp. nov. was proposed for the novel species, with JCM 16988(T) as the type strain. Interestingly, P. churashimaensis was found to produce glycolipid biosurfactants, a mixture of mannosylerythritol lipids (MELs), including a novel tri-acetylated derivative (MEL-A2), from glucose. The observed critical micelle concentration (CMC) and the surface tension at CMC of MEL-A2 were 1.7 × 10?? M and 29.2 mN/m, respectively. Moreover, on a water-penetration scan, MEL-A2 efficiently formed different lyotropic liquid crystalline phases, including the lamella phase at a wide range of concentrations, indicating its excellent surface-active and self-assembling properties. The novel strain of the genus Pseudozyma should thus facilitate the application of glycolipid biosurfactants in combination with other MEL producers.     

Identification of the gene PaEMT1 for biosynthesis of mannosylerythritol lipids in the basidiomycetous yeast Pseudozyma antarctica

The yeast Pseudozyma antarctica produces a large amount of glycolipid biosurfactants known as mannosylerythritol lipids (MELs), which show not only excellent surface‐active properties but also versatile biochemical actions. To investigate the biosynthesis of MELs in the yeast, we recently reported expressed sequence tag (EST) analysis and estimated genes expressing under MEL production conditions. Among the genes, a contiguous sequence of 938 bp, PA_004, showed high sequence identity to the gene emt1, encoding an erythritol/mannose transferase of Ustilago maydis, which is essential for MEL biosynthesis. The predicted translation product of the extended PA_004 containing the two introns and a stop codon was aligned with Emt1 of U. maydis. The predicted amino acid sequence shared high identity (72%) with Emt1 of U. maydis, although the amino‐terminal was incomplete. To identify the gene as PaEMT1 encoding an erythritol/mannose transferase of P. antarctica, the gene‐disrupted strain was developed by the method for targeted gene disruption, using hygromycin B resistance as the selection marker. The obtained ΔPaEMT1 strain failed to produce MELs, while its growth was the same as that of the parental strain. The additional mannosylerythritol into culture allowed ΔPaEMT1 strain to form MELs regardless of the carbon source supplied, indicating a defect of the erythritol/mannose transferase activity. Furthermore, we found that MEL formation is associated with the morphology and low‐temperature tolerance of the yeast. Copyright © 2010 John Wiley & Sons, Ltd.     

The role of PaAAC1 encoding a mitochondrial ADP/ATP carrier in the biosynthesis of extracellular glycolipids,mannosylerythritol lipids,in the basidiomycetous yeast Pseudozyma antarctica

Pseudozyma antarctica produces large amounts of the glycolipid biosurfactants known as mannosylerythritol lipids (MEL), which show not only excellent surface‐active properties but also versatile biochemical actions. A gene homologous with a mitochondrial ADP/ATP carrier was dominantly expressed in P. antarctica under MEL‐producing conditions on the basis of previous gene expression analysis. The gene encoding the mitochondrial ADP/ATP carrier of P. antarctica (PaAAC1) contained a putative open reading frame of 954 bp and encodes a polypeptide of 317 amino acids. The deduced translation product shared high identity of 66%, 70%, 69%, 74%, 75% and 52% with the mitochondrial ADP/ATP carrier of Saccharomyces cerevisiae (AAC1), S. cerevisiae (AAC2), S. cerevisiae (AAC3), Kluyveromyces lactis (KlAAC), Neurospora crassa (NcAAC) and human (ANT1), respectively, and conserved the consensus sequences of all ADP/ATP carrier proteins. The gene expression by introducing a plasmid pUXV1‐PaAAC1 into the yeast cells increased the MEL production. In addition, the expression of PaAAC1 in which the conserved arginine and leucine required for ATP transport activity were replaced with isoleucine and serine, respectively, failed to increase MEL production. Accordingly, these results suggest that PaAAC1 encoding a mitochondrial ADP/ATP carrier should be involved in MEL biosynthesis in the yeast. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of lipids on the properties of emulsified interfacial film of myofibrillar protein by Raman spectroscopy

The purpose of this study was to detect the effects of lipids on the properties of emulsified myofibrillar protein (MP) interfacial layer by Raman spectroscopy combined with the protein adsorption characteristics. Results revealed that compared with butter and lard groups, the α-helix content in the soybean oil emulsifying layer was decreased (P < 0.05), while β-sheets and β-turns were increased (P < 0.05). The tryptophan bands and the disulphide bonds were higher in the soybean oil emulsifying layer, which implied a secondary structure, covalent bonding and hydrophobic interactions between the different lipids and MP have distinctive features. Moreover, the absolute value of the zeta potential in the soybean oil emulsifying layer was the highest, and the unit interface membrane protein surface loading (Γ_S) was higher, indicating that the soybean oil could form a more stable emulsifying layer with MP.     

乳清浓缩蛋白纳米纤维的制备及其界面性质

乳清浓缩蛋白(WPC)相比β-乳球蛋白和乳清分离蛋白(WPI)成分更为复杂,其热聚合形成纤维聚合物的条件不同于β-乳球蛋白和WPI的形成条件.在pH值为1.8,90 ℃热处理10h的条件下,蛋白质量分数为3％的WPC可形成良好的纤维聚合物.通过测定表观度、乳化性和起泡性,比较乳清浓缩蛋白纤维聚合物与常规聚合物界面性质的差异,结果表明,纳米纤维聚合物具有较低的表观度,乳化性能和起泡性能有显著改善.     

Production of aldehyde oxidases by microorganisms and their enzymatic properties

In order to establish an efficient process to decompose environmentally toxic aldehydes, dioxygen-dependent aldehyde oxidase (ALOD) from microorganisms was first sought, and some bacteria and actinomycetes were found to produce the enzyme in their cells. Methylobacillus sp., Pseudomonas sp. and Streptomyces moderates were selected as the representative ALOD-producing strains and their enzymes were partially purified and characterized. The three ALODs could oxidize a wide range of aldehydes including formaldehyde, aliphatic aldehydes, and aromatic aldehydes, though their preferences differ depending on their producing strains. The other enzymatic properties were also determined with regard to their producing strains. Methylobacillus sp. ALOD had the most acidic optimum pH for its activity and stability and Pseudomonas sp. ALOD had the highest stability against heat treatment. Three native ALODs had molecular weights ranging from 140 to 148 kDa and were composed of three subunits of different sizes: large (85 to 88 kDa), medium-sized (37 to 39 kDa) and small (18 to 23 kDa).     

Physical properties of tempered mixtures of cocoa butter,CBR and CBS fats

Physical characteristics of precrystallised binary mixtures of cocoa butter (CB) and 5, 10, 15, 20, 25 and 30% (w/w) cocoa butter replacer (CBR) or cocoa butter substitute (CBS) were determined. The lipid composition was obtained by chromatography and the solid fat content (SFC) by nuclear magnetic resonance. Tempering was carried out using a lab‐scale agitated jacket vessel reactor. Bars made with tempered samples were submitted to X‐ray diffraction and rupture tests. Snap values of crystallised mixtures decrease with an increase in the amount of alternative fat. X‐ray diffraction patterns confirmed the predominant formation of the beta polymorph habit for CB and beta prime form for CBR and CBS. Mixtures of CB and CBR exhibit chemical compatibility. The knowledge of the snap values and of the variation of SFC with temperature proved to suffice to adequately anticipate the influence of the addition of alternative fats on chocolates physical attributes.     

脂质与淀粉相互作用及其对淀粉性质影响

淀粉是食品重要成分,在食品体系中起到提供热能与影响质构作用,在蒸煮、焙烤等加热过程中,淀粉粒开始吸水膨胀,淀粉性质发生变化。淀粉中脂质或外加入脂质在淀粉加热过程中,影响淀粉特性变化;脂质存在会使淀粉溶胀性和溶解性降低,改变糊化温度和热焓,对淀粉流变性质也会产生影响。     

The relationship between the interfacial properties of surfactants and their toxicity to aquatic organisms

In previous work, the toxicity of several anionic and nonionic surfactants to rotifer (Brachionus calyciflorus) was shown to be highly correlated with interfacial activity. In this study, the relationship between interfacial properties of surfactants and their effects on aquatic organisms is extended to include the toxicity of the cationic surfactant class (homologues of alkyl trimethylammonium chloride and alkyl hydroxyethyl dimethylammonium chloride) to green algae (Selenastrum capricornutum) and the bioconcentration of linear alkylbenzene sulfonate (LAS) isomers and homologues by fish (Pimephales promelas and Ictalurus punctatus). In each case, the interfacial activity is expressed by the physicochemical parameter, delta G0ad/Amin, where delta G0ad is the standard free energy of adsorption of the surfactant at the air/solution interface and Amin is the minimum cross sectional area of the surfactant, or the analogous parameter, delta 1sG0ad/1sAmin, at the solid/liquid interface, where the solid is an immobilized artificial membrane (IAM) that mimics a biological cell membrane. The general nature of the relationship between interfacial activity of surfactants and their biological effects in aquatic systems indicates that sorption to biological membranes is a critical parameter for predicting and understanding environmental effects. While specific interactions probably occur once a surfactant has penetrated a membrane bilayer, nonspecific hydrophobic interactions appear to be driving the sorption process.     

Biopolymer films and the effects of added lipids,nanoparticles and antimicrobials on their mechanical and barrier properties: a review

Packaging made from biodegradable biopolymers such as proteins, polysaccharides and lipids is a promising alternative to synthetic polymers. Films made from these biopolymers exhibit certain disadvantages in terms of their mechanical, barrier and physicochemical properties. Plasticisers, nanoparticles, lipids and antimicrobial compounds can be added to them to improve these properties. The tendency of biopolymer films to brittleness can be mitigated by adding plasticisers and/or nanoparticles. These films also tend to have high water vapour permeability, which can be reduced by adding lipids and/or nanoparticles. Incorporating natural compounds with antimicrobial activity into biopolymer films can provide them the advantages of maintaining food safety and extending shelf life. Addition of plasticisers, nanoparticles, lipids and/or antimicrobial compounds to biopolymer films can help to make them comparable to conventional synthetic films with the advantages that they reduce pollution and are biodegradable.     

Lipozyme RM IM脂肪酶催化酸解制备MLM型结构脂质

采用脂肪酶Lipozyme RM IM催化辛酸、癸酸与大豆油进行酸解反应以制备MLM型结构脂质。通过单因素实验研究底物摩尔比、辛癸酸摩尔比、酶添加量、反应时间、反应温度和初始水分含量对酸解反应的影响。得到适合的反应条件为:底物摩尔比3∶1(总脂肪酸/大豆油),辛酸与癸酸摩尔比(辛酸/癸酸)2.5∶1,酶添加量7.5 wt%(基于底物总重),反应时间5 h,反应温度65℃,加水量1.0 wt%(基于底物总重),得到MLM结构脂脂肪酸组成中辛酸含量为20.0 wt%,癸酸含量为10.5 wt%,两者质量比为1.92。     

Modulation of physicochemical properties of emulsified lipids by chitosan addition

Electrostatic interactions between polysaccharides and proteins at oil–water interfaces alter the physicochemical properties and stability of emulsions. In this research, we studied the influence of chitosan addition on the properties of oil-in-water emulsions containing whey protein-coated lipid droplets. Experiments were carried out under conditions where the protein and polysaccharide had similar charges (pH 3.0) or opposite charges (pH 6.5). At pH 3.0, chitosan addition (0–0.025%) had little influence on droplet charge, aggregation, creaming stability or shear viscosity of whey protein emulsions, which was attributed to the fact that the cationic chitosan molecules did not adsorb to the cationic droplet surfaces due to electrostatic repulsion. At pH 6.5, chitosan addition caused a decrease in particle negative charge, an increase in particle size, a decrease in creaming stability, and an increase in viscosity. These effects were attributed to droplet aggregation caused by charge neutralization and bridging resulting from attraction of cationic chitosan molecules to anionic patches on the protein-coated droplet surfaces. Addition of cationic polyelectrolytes to protein-stabilized emulsions may be utilized to control their physicochemical properties, stability and biological fate, which may be useful for developing commercial products with novel or improved functional properties.     

Optimization of the Production of Total Carotenoids by Sporidiobolus salmonicolor (CBS 2636) Using Response Surface Technique

This work aimed at evaluating the conditions of growth and the recovery of total carotenoids produced by Sporidiobolus salmonicolor (CBS 2636). Optimization of carotenoid production was achieved by experimental design technique. A Plackett–Burman design was used, followed by a complete second-order design, to optimize the concentration of total carotenoids in a conventional medium. Maximum concentration of 1,019 μg l⁻¹ of total carotenoids was obtained in a medium containing 40 g l⁻¹ glucose, 10 g l⁻¹ malt extract, and 14 g l⁻¹ peptone, at 180 rpm, 25 °C, and initial pH of 4.0. So far, no previous systematic study using microorganisms of the genus Sporobolomyces (formerly Sporidiobolus) for production of carotenoids has been reported. In this study, very good yields of carotenoids (1 mg l⁻¹) could be obtained after optimization of fermentation medium and operation conditions.     

Production of luteolin extracts from Reseda luteola and assessment of their dyeing properties

In this work, several experiments were performed sequentially in 50 cm³ shaken tubes and a 1 dm³ stirred extractor, thus allowing methanol to be selected as the most appropriate leaching solvent for luteolin from leaves, stems and flowers of weld (Reseda luteola). The extraction capability of methanol at 25 °C was found to be about 7 times greater than that of boiling water at pH 10. A composite design experiment allowed the effects of particle size and liquid/solid ratio to be determined, thus resulting in an optimal luteolin extraction yield of 8.6 ± 0.2 g kg^?1 dried weld material when leaching plant particles sieved through 0.5 mm openings with 40 dm³ methanol kg^?1. Preliminary dyeing tests on pre‐mordanted raw cotton and wool standard specimens gave rise to dyed specimens with the same greenish‐yellow hue but greater or smaller values of lightness and chroma respectively. Despite all dyed specimens exhibiting a minimum resistance to a simulated acid perspiration solution, the resistance to fading of dyed wool specimens was generally greater than that of cotton ones. © 2002 Society of Chemical Industry     

真菌漆酶的生产、性质和应用

本文总结了真菌漆酶的发酵法生产与活力测定方法，介绍了漆酶的结构和活性部位，重点介绍了漆酶的理化性质和乍物学功能，还详述了真菌漆酶在有机合成、环保、食品和造纸等行业中的应用。