Isolation,characterization, and antifungal application of a biosurfactant produced by Enterobacter sp. MS16

Isolate MS16 obtained from diesel contaminated soil, identified as Enterobacter sp. using 16S rRNA gene analysis produced biosurfactant when grown on unconventional substrates like groundnut oil cake, sunflower oil, and molasses. Of these carbon substrates used, sunflower oil cake showed highest biosurfactant production (1.5 g/L) and reduction in surface tension (68%). The biosurfactant produced by MS16 efficiently emulsified various hydrocarbons. The carbohydrates and fatty acids of the biosurfactants were studied using TLC, FTIR, NMR, and GC‐MS. The carbohydrate composition as determined by GC‐MS of their alditol acetate derivatives showed the predominance of glucose, galactose and arabinose, and hydroxyl fatty acids of chain length of C₁₆ and C₁₈ on the basis of FAMEs analysis. Biosurfactant showed antifungal activity and inhibited the fungal spore germination. Practical applications : Enterobacter sp., MS16 produces a biosurfactant composed of carbohydrates and fatty acids which exhibits excellent surface active properties. Use of industrial wastes for biosurfactant production is economical and facilitates the industrial production of this biosurfactant which has potential antifungal activity.     

Exploration of Staphylococcus nepalensis (KY024500) Biosurfactant towards Microbial Enhanced Oil Recovery

Oleochemicals have long been used as biolubricants, biopolymers, and biosurfactants; an effective alternative to petroleum-based products. The present study explores the biosurfactant potential of a novel strain, isolated from rocks of earthquake-prone area. On the basis of morphological, biochemical and 16S rRNA sequencing analysis, the isolate was identified as Staphylococcus nepalensis (KY024500). A biosurfactant yield 2.39, 1.39, and 0.9 g L⁻¹ was obtained using glycerol, waste orange peel, and diesel as a sole carbon source, respectively. Based on oil recovery experimental findings through sand pack column, the obtained biosurfactant from waste orange peels as a sole carbon source was carried forward for further analysis. Thus, obtained biosurfactant from waste orange peels were subjected to solvent extraction and purified by column chromatography. The purified biosurfactant thus obtained was characterized with the help of fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), gas chromatography-mass spectroscopy (GC–MS), and MALDI TOF MS/mass spectroscopy (MS) analysis. FTIR spectroscopic analysis revealed the presence of a carbonyl, amine, hydroxyl, and methyl as functional groups. The GC–MS analysis showed the presence of benzene dicarboxylic acid diethyl ester and pthalic acid as fatty acids while MALDI TOF MS/MS analysis shows lysin-glycin as a hydrophilic dipeptide moiety. This study also demonstrates Microbial Enhanced Oil Recovery (MEOR) potential of the biosurfactant as more efficient than commercial ones. The biosurfactant obtained from waste orange peel as carbon source was able to facilitate a 20% higher recovery of diesel from sand pack recovery column.     

Production and characterization of glycolipid biosurfactant from Streptomyces enissocaesilis HRB1 and its evaluation for biomedical and bioremediation applications

The aim of this investigation is to produce and characterize biosurfactant from Streptomyces sp. HRB1 and to evaluate its biomedical and bioremediation potential. Biosurfactant producing property of Streptomyces sp. HRB1 isolated from petroleum contaminated soil was confirmed by hemolytic and oil spread assays. Based on the results of FT-IR spectral and GC–MS analysis, the biosurfactant was confirmed as glycolipid type. Biosurfactant from Streptomyces sp. HRB1 exhibited 71% inhibition against Pseudomonas aeruginosa biofilm formation, 77.33% quorum sensing inhibition property against Chromobacterium violeceum MTCC 2656, more than 80% inhibition in antioxidant assays namely, DPPH, ABTS, and metal chelation, promising anti-proliferative activity against leukemia and myeloma cells with low IC₅₀ values, 96% decolorization of malachite green within 48 h of reaction time, and minimal toxicity against normal cell lines in dose-dependent manner. The taxonomic position of the potential strain HRB1 was further confirmed as Streptomyces enissocaesilis HRB1 based on their phenotypic and molecular characteristics. To conclude, Streptomyces enissocaesilis HRB1 isolated from petroleum-contaminated soil is a promising source for low-cost production of glycolipid biosurfactant with potential biomedical and environmental applications such as antiphytofungal, antibiofilm, anti-quorum sensing, antioxidant, anticancer, and dye degradation properties.     

Screening and identification of Pseudomonas aeruginosa AB4 for improved production,characterization and application of a glycolipid biosurfactant using low‐cost agro‐based raw materials

BACKGROUND: The study is focused on (i) screening and taxonomic identity of a bacterial strain for biosurfactant production, and (ii) evaluation of its potential for production of a biosurfactant using agro‐based feedstock(s) and characterization of it for application in the removal of heavy metals. RESULTS: The production of biosurfactant by an isolate Pseudomonas aeruginosa AB4 (identified on the basis of 16S rRNA analysis) using various cost‐effective substrates were examined at conditions 40 °C, 120 rpm for 7 days. It revealed maximum (40 gL^?1) rhamnolipids production and 46% reduction of initial surface tension. Its optimum production was achieved at (i) C:N ratio 10:0.6, (ii) pH 8.5 and (iii) 40 °C. The cell–free supernatant examined for biosurfactant activity by (i) haemolytic assay, (ii) CTAB‐ methylene blue assay, (iii) drop collapse test, (iv) oil spreading technique and (v) EI 24 assay showed its glycolipid nature and stable emulsification. Analysis of partially purified rhamnolipids by (i) thin layer chromatography (TLC), (ii) high performance thin layer chromatography (HPTLC), (iii) high performance liquid chromatography (HPLC), (iv) Fourier transform infrared (FT‐IR) and (v) gas chromatography–mass spectrometry (GC‐MS) confirmed its structure as methyl ester of 3‐hydroxy decanoic acid (a glycolipid) with two major structural congeners (Rha‐C₁₀‐C₁₀ and Rha‐C₁₀‐C₈) of mono‐rhamnolipids. Finally, it showed sequestration of Cd and Pb, suggesting its application in biosurfactant‐assisted heavy metal bioremediation. CONCLUSION: This work has screened and identified a bacterium with superior biosurfactant production capabilities, characterized the glycolipidic biosurfactants as rhamnolipid and indicated the feasibility of biosurfactant production using novel renewable, relatively inexpensive and easily available resources such as non‐edible vegetable de‐oiled seed cakes and showed its utility in remediation of heavy metals. Copyright © 2010 Society of Chemical Industry     

Comparison of aroma,aroma-active,and phenolic compounds of crude and refined hazelnut oils

Hazelnut (Corylus avellana L.) is an important shelled nut with its pleasant aroma. The refining process causes significant changes in the quality attributes of hazelnut oil. The aim of this study was to assess the aroma, aroma-active, and phenolic compounds of the crude and refined hazelnut oils by using gas chromatography–mass spectrometry (GC–MS), GC–MS-olfactometry (GC–MS-O), and liquid chromatography–mass spectrometry (LC–MS/MS). The antioxidant capacities were also determined by DPPH and ABTS methods. Results showed that terpenes and aldehydes constituted a significant portion of the aroma profile. Refining process dramatically reduced the numbers (from 63 to 25) and amounts of aroma compounds (from 36,769 to 4461 μg/kg). Similarly, the numbers of aroma-active compounds were reduced from 22 to 8 by the refining process. Their flavor dilution factors ranged from 2 to 1024 for crude oil and from 2 to 32 in the refined oil. As of the phenolics, five and two compounds were quantified in the crude and refined oil samples, respectively. In sum, the refining process had a considerable adverse effect on the aroma, aroma-active, and phenolic constituents of the hazelnut oil; hence, the refining process has to be planned with minimal negative effect on its organoleptic properties.     

Characterization of Biosurfactant Produced by a Novel Strain of Pseudomonas aeruginosa,Isolate ADMT1

Several biosurfactant‐producing bacterial strains were isolated from petroleum‐contaminated soil. The isolate ADMT1, identified as a new strain of Pseudomonas aeruginosa, was selected for further studies on the basis of oil displacement test and emulsification index (E24). The optimal parameters for production, determined by employing Box–Behnken design, were temperature 36.5 °C and pH 7. The environmental isolate ADMT1 produced significant amount of biosurfactant (1.7 g L^?1 in 72 h) in minimal salt medium (MSM) using dextrose as the sole carbon source. The E24 value and critical micelle concentration (CMC) of the biosurfactant was 100% and 150 mg L^?1, respectively. At CMC, the surface tension of water was reduced to 28.4 mN m^?1. The biosurfactant exhibited hemolytic activity and antibacterial activity against 8 reference strains of pathogenic bacteria, including 2 methicillin‐resistant Staphylococcus aureus strains (MRSA ATCC 562 and MRSA ATCC 43300), with minimum inhibitory concentration (MIC) of 0.4 and 0.2 mg mL^?1, respectively. The structure of biosurfactant was characterized by FTIR, ¹H, and ¹³C NMR spectroscopy. 7 di‐rhamnolipid (RL) congeners were identified in the biosurfactant by ultraperformance liquid chromatography–mass spectrometry analysis. The major congeners, which constituted 67% of the RL mixture, included Rha‐Rha‐C₁₀‐C₁₀, Rha‐Rha‐C₁₂‐C₁₀, and Rha‐Rha‐C_12:1‐C₁₀. The minor congeners were Rha‐Rha‐C₁₀‐C₈, Rha‐Rha‐C_10:1‐C₁₀, Rha‐Rha‐C₁₀‐C_14:1, and Rha‐Rha‐C₁₀‐C₁₄. The congener Rha‐Rha‐C₁₀‐C₁₄ is being reported for the first time from any species of Pseudomonas. The high surface activity and E24 value make the ADMT1‐RL a potential candidate for its use in detergents, environmental bioremediation, and as an emulsifier in the food industry.     

Separation and Purification of Z Ligustilide and Senkyunolide A from Ligusticum chuanxiong Hort. with Supercritical Fluid Extraction and High‐Speed Counter‐Current Chromatography

Abstract

The essential oil was obtained by supercritical fluid extraction from dried roots of Ligusticum chuanxiong. Different solvent systems for high‐speed counter‐current chromatography (HSCCC) were compared. A system composed of n hexane–ethyl acetate–methanol–water–acetonitrile in the ratio of 8:2:5:5:3 (v/v) was found to be optimum for HSCCC of the essential oil. Z ligustilide and senkyunolide A were separated by HSCCC with purity of 98% determined by GC. The chemical structures of these two components were identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS).     

Recycling of Bakery Waste as an Alternative Carbon Source for Rhamnolipid Biosurfactant Production

Production of a rhamnolipid biosurfactant (RBS) using discarded mixed bakery waste (BW) employing bacterial strain Pseudomonas aeruginosa strain PG1 (identified by 16 s rDNA sequencing) was investigated for bioconversion of the food waste. Dry and powder form BW was supplemented with mineral salt media (MSM) as a sole carbon source for production of RBS. RBS production was measured based on the drop collapse assay and surface tension (ST) reduction of the culture media. Production of RBS in the culture media was enhanced by optimizing the carbon source (BW) concentration and the proper nitrogen source along with the pH of the MSM. Under optimized culture conditions, 11.56 g L⁻¹ day⁻¹ crude biosurfactant (BS) was achieved. The RBS had the ability to reduce the ST of the optimized MSM from 72.0 to 25.8 mN m⁻¹ during culture, where the critical micelle concentration (CMC) of the biosurfactant was found to be 100 mg L⁻¹. Liquid Chromatography Mass Spectroscopy (LC-MS), Fourier Transform Infrared spectroscopy (FTIR), and scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy (EDS) analyses of the purified BS confirmed that it is of rhamnolipid in nature and it is made up of both monorhamnolipid and dirhamnolipid congeners. Furthermore, the RBS did not express any cytotoxic effect on the cell line of mouse L292 fibroblastic cell indicating the biosafety nature of the high-value biomolecule.     

Studies on Biosurfactants Produced using Bacillus cereus Isolated from Seawater with Biotechnological Potential for Marine Oil-Spill Bioremediation

With the aim of producing a biotensioactive material for use in the remediation of marine environments, screening for biosurfactant-producing bacteria was conducted with strains isolated from seawater contaminated with petroleum derivatives. Gene sequencing revealed that all four promising biosurfactant-producing isolates belonged to the same genus and species, namely Bacillus cereus. The biosurfactant-producing bacteria were cultivated with different carbon (glucose, soybean oil, and waste frying soybean oil) and nitrogen (ammonium chloride, sodium nitrate, urea, and peptone) sources. B. cereus strain BCS0 was chosen as the best biosurfactant producer in a mineral medium with 2% frying oil and 0.12% peptone. Following the optimization of agitation and cultivation time, an agitation rate of 250 rpm and 48 h of cultivation were selected. Under these conditions, the surface tension was reduced to 27 mN m⁻¹ and the biosurfactant concentration was 3.5 g L⁻¹. The critical micelle concentration (CMC) of the biosurfactant was defined as 500 mg L⁻¹. The biosurfactant remained stable within large ranges of pH (2–10), salinity (2–10%), and temperature (5–120 °C). Under these conditions, motor oil emulsification rates were greater than 90%. Moreover, the biosurfactant properties remained unaltered after heating at 90 °C for 120 min. The biosurfactant enhanced the degradation of motor oil up to 96% in 27 days and exhibited considerable motor oil displacement capacity. Thus, the biosurfactant has potential in the application of remediation processes in marine environments.     

Use of biosurfactant in the removal of oil from contaminated sandy soil

The effectiveness of cell‐free rhamnolipid biosurfactant, derived from the culture medium at the end of fermentation was investigated for the removal of two different kinds of oil from contaminated sandy soils. The crude cultivation medium, containing 13.2 g L^?1 of rhamnolipids, had a surface tension, interfacial tension and critical micellar concentration of 30 mN m^?1, 2 mN m^?1 and 60 mg L^?1, respectively. The evaluation of biosurfactant in the culture medium (BM) and oil concentrations in the removal of oil from different contaminated sandy soil was performed using a statistical experimental design tool. Oil in sandy soil, containing predominantly aromatic or paraffinic hydrocarbons (5 to 10% w/w), was removed by as much as 91 and 78%, respectively, in the presence of reduced amounts of BM (6.3 to 7.9 g L^?1). The progress of oil removal was monitored for 101 days and results indicated that removal efficiency in sandy soil with aromatic characteristics was relatively stable over the entire period. Based on these studies, it is concluded that use of a BM was effective in reducing oil concentrations in contaminated sandy soil. Copyright © 2007 Society of Chemical Industry     

Chicken Tallow,a Renewable Source for the Production of Biosurfactant by Yarrowia lipolytica MTCC9520, and its Application in Silver Nanoparticle Synthesis

The present study is focused on the production of a biosurfactant using Yarrowia lipolytica MTCC 9520 by employing inexpensive lipid waste, chicken tallow from slaughterhouses. Plackett–Burman and Box–Behnken Design analyses were adopted for preliminary screening of medium variables and further optimization. The maximal yield of 4.4 g L⁻¹ of the biosurfactant was obtained from the optimized medium. The highest emulsification activity was found to be 55%, and the surface tension decreased to 37 mN m⁻¹ at the end of 96 h. The critical micelle concentration of the biosurfactant was calculated as 1.2%. The produced biosurfactant was characterized as cationic lipoprotein in type, and the proteins present in the biosurfactant were observed to have molecular weights between 75 and 100 kDa. The fatty acids composition of the biosurfactant was detected by gas chromatography–mass spectrometry (GC–MS) analysis. Fourier transform infra red (FTIR) and nuclear magnetic resonance (NMR) analysis confirmed the lipoprotein nature of the extracted biosurfactant. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis revealed the thermostable nature of the extracted biosurfactant. Surface plasmon resonance vibration peak at 421 nm was observed for the surfactant-stabilized silver nanoparticles (AgNP) through UV–Vis spectrophotometry. The average particle size of the synthesized AgNP was calculated as 7.2 ± 0.4 nm from transmission electron microscopy (TEM) analysis. Energy dispersive x-ray (EDX) spectroscopy exhibited the presence of silver in the synthesized nanoparticles. The zeta potential value of the synthesized AgNP was measured as −22.2 mV, and the polydispersity index was found as 2.3 through dynamic light scattering (DLS) analysis.     

Achieving the Best Yield in Glycolipid Biosurfactant Preparation by Selecting the Proper Carbon/Nitrogen Ratio

Pseudomonas aeruginosa RS29, the native biosurfactant-producing strain isolated from the oil fields of Assam, India was used to investigate the influence of the carbon nitrogen ratio on production of the biosurfactant. The biosurfactant producing ability of the strain was measured based on surface tension (ST) reduction of the culture medium and the emulsification (E24) index. Production was greatly influenced by the sources of nitrogen and carbon as well as the carbon to nitrogen (C/N) ratio. Sodium nitrate was the best nitrogen source and the water miscible carbon source, glycerol was observed as the best carbon source for maximum biosurfactant production. The C/N ratio 12.5 allowed the maximum production of biosurfactant by the RS29 strain. At this C/N ratio, 55 % ST of the culture medium was reduced by the produced biosurfactant. Concentrations of crude and rhamnolipid biosurfactant obtained at this particular C/N ratio were 5.6 and 0.8 g/l respectively. The RS29 strain was novel as it was able to produce a sufficient amount of biosurfactant utilizing a much lower amount of the water miscible carbon source, glycerol. Extraction of the biosurfactant by a chloroform–methanol (2:1) mixture was the best method to obtain the highest biosurfactant from the culture medium of the strain. The biosurfactant was confirmed as a mixture of mono and di-rhamnolipid congeners, Rha–C₁₀–C₁₀–CH₃ being the most abundant one. The biosurfactant was a good foaming and emulsifying agent.     

Enhanced bioremediation of crude oil‐contaminated soil by a Pseudomonas species and mutually associated adapted Azotobacter vinelandii

A mixed culture of compatible hydrocarbonoclastic and diazotrophic bacteria, each at a density of 10⁸ organisms cm^?3, was developed for optimised bioremediation of crude oil‐contaminated soil. The hydrocarbonoclastic bacterium, Pseudomonas sp and the diazotroph, Azotobacter vinelandii, were both isolated from a previously crude oil‐contaminated soil and thereafter modelled as a unit of mutualistic consortium in situ. Stabilisation of the consortium and hence the optimised bioremediation process occurred when the bacterial growth attained a pseudo‐steady state condition. This was considered to be as a result of a symbiotic association between A vinelandii and the Pseudomonas sp in which A vinelandii produced the required concentration of fixed nitrogen compounds required for the growth of the Pseudomonas sp. Enhancement in biodegradation, due to stimulated growth of Pseudomonas sp and co‐metabolic activity of A vinelandii, was mathematically evaluated as the difference in the specific growth rates (µ) between the consortium Pseudomonas sp/A vinelandii and Pseudomonas sp alone. The proportion of petroleum hydrocarbons degraded by the consortium from the contaminated soil ranged between 66.83 and 69.6% as compared with that of a pure culture of Pseudomonas sp (23.2–44.45%). Hence, beyond their role in biological nitrogen fixation, diazotrophs may be used to contribute to bioremediation of crude oil‐contaminated land. Copyright © 2004 Society of Chemical Industry     

Isolation and Identification of Current Biosurfactant-Producing Microbacterium maritypicum ABR5 as a Candidate for Oily Sludge Recovery

Biosurfactants have a wide range of applications in different areas, including petroleum microbiology and environmental biotechnology. In this study, removing and recovering oil from oily sludge using microbactan-producing bacteria have been investigated. The best biosurfactant-producing isolate was obtained from a petroleum reservoir and was identified by 16S rDNA analysis as Microbacterium maritypicum ABR5. Its 16S rDNA sequence was deposited in GenBank, NCBI under the accession number MK100468. Chemical analysis using thin-layer chromatography and Fourier Transform Infrared confirmed that the produced biosurfactant was glycolipoprotein. The strain reduced surface tension from 72 to 34.6 mN m⁻¹. The addition of 5 mg L ZnO nanoparticles to the biosurfactant-producing medium showed no bacterial toxicity effect and raised the emulsification index to 25.7%. Higher concentrations of ZnO nanoparticles, such as 10 and 100 mg L, decreased the bacterial growth rate and biosurfactant production. The mixing of M. maritypicum ABR5 culture medium and oily sludge increased the oil recovery from oily sludge by up to 70% after 5 days of incubation. This is the first report of biosurfactant production by a newly identified strain, M. maritypicum ABR5, isolated from a petroleum reservoir. We proposed that the isolated biosurfactant-producing strain could be considered an economical asset for oil recovery from oily sludge in the petroleum industry and environmental biotechnology.     

一株耐温耐盐烃降解菌Geobacillus sp. XDF-4性能

从大庆油田龙虎泡区块采油地层水中分离得到一株性能很好的耐盐耐温的兼性烃降解菌XDF-4,经形态观察、生理生化实验和16SrDNA基因序列分析,初步鉴定为地芽孢杆菌Geobacillus sp.。该菌在45～75℃、pH 6.5～9.0、盐的质量分数0～10%下生长良好,其最适生长温度为65℃,最适盐的质量分数为 3.0%。研究发现,该菌株能以原油为唯一碳源生长并合成生物表面活性剂, 发酵相似文献   

中间苍白杆菌对含蜡原油除蜡降粘分析

蜡质不仅使含蜡原油黏度升高，而且会析出积聚在管壁上降低管输效率。从原油污染淤泥中分离出一株产表面活性剂的烃降解菌F-1，经16S rDNA鉴定为中间苍白杆菌。与原油作用7 d 后，能将蜡含蜡量为15.2%的高含蜡原油处理为蜡含蜡量为9.1%的含蜡原油，原油蜡质量分数降低40.1%，原油黏度降低21%以上，细胞疏水性达28.1%。通过傅里叶红外光谱鉴定该菌产生的生物表面活性剂为脂肽类。添加该菌上清液到液体石蜡 可形成91.49 mm的排油圈，能够显著降低培养基表面张力，对液体石蜡乳化系数达到65%。     

Identification and Characterization of Phospholipids with Very Long Chain Fatty Acids in Brewer’s Yeast

Yeast lipids and fatty acids (FA) were analyzed in Saccharomyces pastorianus from seven breweries and in the dietary yeast supplement Pangamin. GC–MS identified more than 30 FA, half of which were very‐long chain fatty acids (VLCFA) with hydrocarbon chain lengths of ≥22 C atoms. Positional isomers ω‐9 and ω‐7 were identified in FA with C18–C28 even‐numbered alkyl chains. The most abundant ω‐7 isomer was cis‐vaccenic acid. The structure of monounsaturated FA was proved by dimethyl disulfide adducts (position of double bonds and cis geometric configuration) and by GC–MS of pyridyl carbinol esters. Ultra‐high performance liquid chromatography‐tandem mass spectrometry with negative electrospray ionization identified the phospholipids phosphatidylethanolamine, phosphatidylinositol and phosphatidylcholine, with more than 150 molecular species. Wild‐type unmutated brewer's yeast strains conventionally used for the manufacture of food supplements were found to contain VLCFA.     

Characterization of Crude and Partially Purified Lipase from Geotrichum candidum Obtained with Different Nitrogen Sources

Lipases from Geotrichum candidum were produced in two different medium: A = 12 % (w/v) clarified corn steep liquor (CCSL) + 0.6 % (w/v) soybean oil (SO) and B = 3.5 % (w/v) yeast hydrolysate (YH) + 0.7 % (w/v) SO. Lipases were partially purified from both media by hydrophobic interaction chromatography using 3.0 mol L^?1 of NaCl as mobile phase, and they were characterized in the crude and partially purified forms. The recovery of lipase activity from CCSL and YH via HIC were 96 and 94.3 %, and the purification factors were 44.3 and 86.7‐fold, respectively. All evaluated lipases had similar optimum pH (7.0–7.7), but, for the CCSL crude lipase, optimum temperature (47 °C) was 10 °C higher than others lipases evaluated. CCSL crude lipase possessed a higher thermo stability than YH crude lipase, e.g., at 37 °C (pH 7.0) the half‐life of CCSL crude lipase was 19.25 h and at pH 8.0 (30 °C) the half‐life was 48 h, which are five and ten times higher than with YH crude lipase, respectively. On the other hand, the YH crude lipase possessed a higher catalytic constant (k_cat = 2.3 min^?1) but with almost the same catalytic efficiency (K_m/k_cat = 32.12 mg mL min^?1) in relation to CCSL crude lipase. The lipases differ in biocatalytic properties between substrates, suggesting that the two lipases can be employed for different applications.     

Brewer’s Yeast as a New Source of Palmitoleic Acid—Analysis of Triacylglycerols by LC–MS

We identified both fatty acids and TAG in waste yeast from seven breweries employing both top and bottom fermentation. Brewer′s yeast was found to contain FA exhibiting a broad range of acyl chain lengths, with a high proportion of the nutritionally and biotechnologically important palmitoleic acid. Analysis of FA by GC–MS and of TAG by LC–MS with APCI provided information on the type of brewer′s yeast and technology of fermentation. The composition of TAG containing major FA such as palmitic, palmitoleic and oleic acid was found to depend not only on the type of yeast strain, i.e. Saccharomyces pastorianus or S. cerevisiae, but also on brewing fermentation process, i.e. top versus bottom fermentation. Top and bottom yeast can readily be distinguished by the ratios of some regioisomers of TAG since, e.g., the ratio of regioisomers PoOPo and PoPoO is always >1 in top fermenting yeast and <1 in bottom yeast. The ratios can thus be used as markers for determining the yeast type and beer-producing technology in a given brewery.     

鼠李糖脂在土壤污染修复中的应用研究进展

介绍了生物表面活性剂鼠李糖脂在土壤重金属污染的修复作用及对土壤中原油、多氯联苯、多环芳烃等污染物的降解作用,并且廉价、无毒、可生物降解,具有广阔的应用前景。