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1.
H. Noureddini X. Gao S. Joshi P. R. Wagner 《Journal of the American Oil Chemists' Society》2002,79(1):33-40
The immobilization of Lipase PS from Pseudomonas cepacia by entrapment within a chemically inert hydrophobic solgel support was studied. The gel-entrapped lipase was prepared by
the hydrolysis of tetramethoxysilane (TMOS) with methyltrimethoxysilane (MTMS), isobutyltrimethoxysilane (iso-BTMS), and n-butyltrimethoxysilane. The immobilized lipase was subsequently used in the hydrolysis of soybean oil to determine its activity,
recyclability, and thermostability. The biocatalyst so prepared was equal to or better than the free enzyme in its hydrolytic
activity. The catalytic activity of the entrapped lipase strongly depended on the type of precursor that was used in its preparation.
The lipase entrapped within TMOS/iso-BTMS showed the highest activity. The catalytic activity of the immobilized lipase was
more pronounced during the earlier stages of the reaction. Thermostability of the lipase was significantly improved in the
immobilized form. The immobilized lipase was stable up to 70°C, whereas for the free enzyme, moderate to severe loss of activity
was observed beyond 40°C. The immobilized lipase was consistently more active and stable than the free enzyme. The immobilized
lipase also proved to be very stable, as it retained more than 95% of its initial activity after twelve 1-h reactions. 相似文献
2.
Yomi?Watanabe Yoshie?Yamauchi-Sato Toshihiro?Nagao Takaya?Yamamoto Kentaro?Tsutsumi Akio?Sugihara Yuji?Shimada
We attempted to produce MAG of CLA through lipase-catalyzed esterification of a FFA mixture containing CLA (referred to as
FFA-CLA) with glycerol. Screening of lipases showed that MAG-CLA was produced efficiently at 5°C with Penicillium camembertii, Rhizopus oryzae, and Candida rugosa lipases. Among them, C. rugosa lipase was selected because the lipase is widely used as a catalyst for oils and fats processing. The reaction was conducted
with agitation of a 300-g mixture of FFA-CLA/glycerol (1∶5, mol/mol), a 200-U/g mixture of C. rugosa lipase, and 2% water. When the reaction was conducted at 30°C, the esterification scarcely proceeded, owing to inhibition
of the reaction by glycerol. But the reaction at 5°C eliminated the inhibition and produced MAG efficiently: The degree of
esterification reached 93.8% after 58 h, and MAG content in the reaction mixture was 88.4 wt%. To reduce the reaction time,
the reactor was connected with a vacuum pump after 24 h, and the reaction was continued with dehydration at 5 mm Hg. The degree
of esterification reached 94.7% after 24 h of dehydration (48 h in total), and MAG content increased to 93.0 wt%. Candida rugosa lipase acted a little more strongly on cis-9, trans-11 CLA than on trans-10,cis-12 CLA, but the contents of the two isomers in MAG obtained from a 48-h reaction were the same as the contents in FFA-CLA. 相似文献
3.
The purification of tocopherols and phytosterols (referred to as sterols) from soybean oil deodorizer distillate (SODD) was
attempted. Tocopherols and sterols in the SODD were first recovered by short-path distillation, which was named sODD tocopherol/sterol
concentrate (SODDTSC). The SODD-TSC contained MAG, DAG, FFA, and unidentified hydrocarbons in addition to the two substances
of interest. It was then treated with Candida rugosa lipase to convert sterols to FA steryl esters, acylglycerols to FFA, and FFA to FAME. Methanol (MeOH), however, inhibited
esterification of the sterols. Hence, a two-step in situ reaction was conducted: SODDTSC was stirred with 20 wt% water and 200 U/g mixture of C. rugosa lipase at 30°C, and 2 moles of MeOH per mole of FFA was added to the reaction mixture after 16h. The lipase treatment for
40 h in total achieved 80% conversion of the initial sterols to FA steryl esters, complete hydrolysis of the acylglycerols,
and a 78% decrease in the initial FFA content by methyl esterification. Tocopherols did not change throughout the process.
To enhance the degree of steryl and methyl esterification, the reaction products, FA steryl esters and FAME, were removed
by short-path distillation, and the resulting fraction containing tocopherols, sterols, and FFA was treated with the lipase
again. Distillation of the reaction mixture purified tocopherols to 76.4% (recovery, 89.6%) and sterols to 97.2% as FA steryl
esters (recovery, 86.3%). 相似文献
4.
Acid oil is a by-product in the neutralization step of vegetable oil refining and is an alternative source of biodiesel fuel.
A model substrate of acid oil, which is composed of TAG and FFA, was used in experiments on the conversion to FAME by immobilized
Candida antarctica lipase. FFA in the mixture of TAG/FFA were efficiently esterified with methanol (MeOH), but the water generated by the esterification
significantly inhibited methanolysis of TAG. We thus attempted to convert a mixture of TAG/FFA to FAME by a two-step process
comprising methyl esterification of FFA and methanolysis of TAG by immobilized C. antarctica lipase. The first reaction was conducted at 30°C in a mixture of TAG/FFA (1∶1, wt/wt) and 10 wt% MeOH using 0.5 wt% immobilized
lipase, resulting in efficient esterification of FFA. The reaction mixture after 24 h was composed of 49.1 wt% TAG, 1.3 wt%
FFA, 49.1 wt% FAME, and negligible amounts of DAG and MAG (<0.5 wt%). The reaction mixture was then dehydrated and used as
a substrate for the second reaction, which was conducted at 30°C in a solution of the dehydrated mixture and 5.5 wt% MeOH
using 6 wt% immobilized lipase. The activity of the lipase increased gradually when the reaction was repeated by transferring
the enzyme to a fresh substrate mixture. The activity reached a maximum after 6 cycles, and the content of FAME achieved was
>98.5 wt% after a 24-h reaction. The immobilized lipase was very stable in the first-and second-step reactions and could be
used for >100 d without significant loss of activity. 相似文献
5.
Purification of arachidonic acid (AA) from Mortierella alpina single-cell oil was attempted. The process comprised three steps: (i) preparation of FFA by nonselective hydrolysis of the
oil with Alcaligenes sp. lipase; (ii) elimination of long-chain saturated FA from the resulting FFA by urea adduct fractionation; and (iii) enrichment
of AA through lipase-catalyzed selective esterification with lauryl alcohol (LauOH). In the third step, screening of industrially
available lipases indicated that Burkholderia cepacia lipase (Lipase-PS, Amano Enzyme Inc., Aichi, Japan) acted on AA more weakly than on other FA and was the most effective for
enrichment of AA in the FFA fraction. When the FFA obtained by urea adduct fractionation were esterified with 2 molar equivalents
of LauOH at 30°C for 16 h in a mixture with 20% water and 20 units (U)/g-mixture of Lipase-PS, the esterification reached
39% and the content of AA in the FFA fraction was raised from 61 to 86 wt%. To further increase the content of AA, unesterified
FFA were allowed to react again under the same conditions as those in the first selective esterification except for the use
of 50 U/g Lipase-PS. A series of procedures raised the content of AA to 97 wt% with a 49% recovery based on the initial content
in the single-cell oil. These results indicated that the three-step process for selective esterification with Lipase-PS was
effective for purifying AA from the single-cell oil. 相似文献
6.
An industrially available preparation of astaxanthin (Ax) from Haematococcus pluvialis contained 41.6 wt% acylglycerols and 24.9 wt% FFA in addition to 14.6 wt% Ax, which was a mixture of free and FA ester forms
(free Ax/Ax monoesters/Ax diesters=4.9∶80.3∶14.8, by mol). Enrichment of Ax by a two-step process was attempted. The first
step was hydrolysis of acylglycerols with Candida rugosa lipase: A mixture of 1.0 kg H. pluvialis cell extracts, 1.0 L water, and 50 U/g-reaction mixture of the lipase was agitated at 30°C for 42 h. The degree of hydrolysis
of acylglycerols reached 94.4%, but Ax esters were not hydrolyzed. Removal of FFA from the resulting oil layer by molecular
distillation enriched the content of Ax esters to 40.8 wt5 (named Ax40). The second step was enzymatic conversion of Ax esters
to free Ax, which successfully proceeded in the presence of ethanol (EtOH). When a mixture of 50.0 g Ax40, 8.2 g EtOH (5 molar
equiv. against FA), 58.2 mL water, and 1500 U/g-mixture of Pseudomonas aeruginosa lipase was stirred at 30°C for 68 h, the free Ax content increased to 89.3 mol%. Free Ax was efficiently recovered by precipitation
with n-hexane. The purity of Ax was thereby raised to 70.2 wt% with a 63.9% overall recovery of the initial content in the cell
extracts. 相似文献
7.
This study utilized γ-linolenic acid (18∶3n−6; GLA)-rich borage oil (BO) and evening primrose oil (EPO) for the synthesis
of structured lipids (SL) and compared the oxidative stability of the products with those of unmodified BO and EPO as controls.
Immobilized Novozym 435 lipase from Candida antarctica was used as the biocatalyst for SL production. BO or EPO eas enzymatically modified with docosahexaenoic acid (22∶6n−3; DHA),
as the acyl donor, to produce SI. The SI were characterized and their oxidative stabilities evaluated. Among the oils examined,
SL gave rise to higher quantities (P≤0.05) of conjugated dienes, TBARS, and headspace volatiles as compared to their unmodified counterparts. Results indicated
that modified oils were less stable than their unmodified counterparts. The double bond index (DBI) and methylene bridge index
(MBI) of oils decreased (P<0.05) during oxidation in the more unsaturated oils. An attempt was made to correlate various parameters of oxidation with
DBI and MBI of oils; correlation coefficients (−r) were within the range of 0.574–0.973. This suggests that indicators such as DBI and MBI can reflect oxidative stability
of oils. 相似文献
8.
Reaction selectivities were determined in multicompetitive reactions mediated by Burkholderia cepacia lipase (Amano PS-30) at a water activity of 0.19 in hexane. Saturated FA (C4–C18 even chain) and oleic acid (C18∶1) were
reacted with a single alcohol, glycerol, α-or β-MAG, containing C4, C10, C16, or C18∶1 individually as alcohol cosubstrate.
Similar odrinal patterns of FA selectivity, with C8, C10, and C16 preferred over others, were generally observed for incorporation
of FA into specific acylglycerol (AG) pools of the 24 specific cases evaluated. The three exceptions were enrichment of C14
and C18 in the MAG pool with α-C16-MAG, substrate, and a general suppression of >C8 incorporation into the TAG pool for reactions
with α-C10- and α-C16-MAG. PS-30 lipase selectivity toward MAG was in descending order: α/β-C4-MAG>β-C10-MAG>β-C16-MAG>α/β-C18∶1-MAG>α-C10-MAG>α-C16-MAG.
Selectivity in channeling CX of the original CX-MAG substrates into higher AG species was in descending order: α-C10-MAG∼α-C16-MAG>α-C18∶1-MAG>β-C10-MAG∼β-C16-MAG∼β-C18∶1-MAG
>α/β-C4-MAG. Generally, MAG were better acyl donors than FA for esterification reactions leading to DAG formation. These observations
are relevant to the design of biocatalytic processes intended to yield specifically structured TAG. 相似文献
9.
J.-F. Butaud P. Raharivelomanana J.-P. Bianchini E. M. Gaydou 《Journal of the American Oil Chemists' Society》2008,85(4):353-356
The sandalwood kernels of Santalum insulare (Santalaceae) collected in French Polynesia give seed oils containing significant amounts of ximenynic acid, E-11-octadecen-9-oic acid (64–86%). Fatty acid (FA) identifications were performed by gas chromatography/mass spectrometry
(GC/MS) of FA methyl esters. Among the other main eight identified fatty acids, oleic acid was found at a 7–28% level. The
content in stearolic acid, octadec-9-ynoic acid, was low (0.7–3.0%). An inverse relationship was demonstrated between ximenynic
acid and oleic acid using 20 seed oils. Results obtained have been compared to other previously published data on species
belonging to the Santalum genus, using multivariate statistical analysis. The relative FA S. insulare composition, rich in ximenynic acid is in the same order of those given for S. album or S. obtusifolium. The other compared species (S. acuminatum, S. lanceolatum, S. spicatum and S. murrayanum) are richer in oleic acid (40–59%) with some little differences in linolenic content. 相似文献
10.
Yuji Shimada Nobuhiro Fukushima Hiroyuki Fujita Yo Honda Akio Sugihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》1998,75(11):1581-1586
A 46% γ-linolenic acid (GLA)-containing oil was produced by selective hydrolysis of borage oil (GLA content, 22%) at 35°C
for 15 h in a mixture containing 50% water and 20 units (U)/g reaction mixture of Candida rugosa lipase. The GLA content was not raised over 46%, even though the hydrolysis extent was increased by extending the reaction
time and by using a larger amount of the lipase. However, 49% GLA-containing oil was produced by hydrolysis in a reaction
mixture with 90% water. This result suggested that free fatty acids (FFA) that accumulated in the mixture affected the apparent
fatty acid specificity of the lipase in the selective hydrolysis and interfered with the increase of the GLA content. To investigate
the kinetics of the selective hydrolysis in a mixture without FFA, glycerides containing 22, 35, and 46% GLA were hydrolyzed
with Candida lipase. The result showed that the hydrolysis rate decreased with increasing GLA content of glycerides, but that the release
rate of GLA did not change. Thus, it was found that the apparent fatty acid specificity of the lipase in the selective hydrolysis
was also affected by glyceride structure. When 46% GLA-containing oil was hydrolyzed at 35°C for 15 h in a mixture containing
50% water and 20 U/g of the lipase, GLA content in glycerides was raised to 54% at 20% hydrolysis. Furthermore, GLA content
in glycerides was raised to 59% when the hydrolysis extent reached 60% using 200 U/g of the lipase. These results showed that
repeated hydrolysis was effective to produce the higher concentration of GLA oil. Because film distillation was found to be
extremely effective for separating FFA and glycerides, large-scale hydrolysis of borage oil was attempted. As a result, 1.5
kg of 56% GLA-containing oil was obtained from 7 kg borage oil by repeated reaction. 相似文献
11.
The FA composition in the sn-2 position of TAG is routinely determined after porcine pancreatic lipase hydrolysis. However, the content of saturated FA
increased when a pancreatic lipase preparation with higher specific activity was used. Lipase from Rhizopus delemar was selected as a potential replacement lipase for the following reasons: (i) The FA specificity is nearly equivalent in
hydrolysis activity toward FA such as lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and α-linolenic acids;
and (ii) lipase from R. delemar hydrolyzes fatty acyl residues at the sn-1,3 positions of TAG. Acyl migration products were present at less than 0.8% in lipase hydrolysates containing 6–14% of sn-2 MAG. A reproducibility CV of less than 5% was obtained in a collaborative study in which the compositions of the main FA
at the sn-2 position in olive oil were determined using lipase from R. delemar.
This article was presented in part at the Biocatalysis Symposium, 94th AOCS Annual Meeting & Expo, Kansas City, Missouri,
May 2003. 相似文献
12.
Ralphs MH Creamer R Baucom D Gardner DR Welsh SL Graham JD Hart C Cook D Stegelmeier BL 《Journal of chemical ecology》2008,34(1):32-38
Locoweeds (Astragalus and Oxytropis spp. that contain the toxic alkaloid swainsonine) cause widespread poisoning of livestock on western rangelands. There are
354 species of Astragalus and 22 species of Oxytropis in the US and Canada. Recently, a fungal endophyte, Embellisia spp., was isolated from Astragalus and Oxytropis spp. and shown to produce swainsonine. We conducted a survey of the major locoweeds from areas where locoweed poisoning has
occurred to verify the presence of the endophyte and to relate endophyte infection with swainsonine concentrations. Species
found to contain the fungal endophyte and produce substantial amounts of swainsonine were A. wootoni, A. pubentissimus, A. mollissimus, A. lentiginosus, and O. sericea. Astragalus species generally had higher concentrations of swainsonine than Oxytropis. Swainsonine was not detected in A. alpinus, A. cibarius, A. coltonii, A. filipes, or O. campestris. The endophyte could not be cultured from A. mollissimus var. thompsonii or A. amphioxys, but was detected by polymerase chain reaction, and only 30% of these samples contained trace levels of swainsonine. Further
research is necessary to determine if the endophyte is able to colonize these and other species of Astragalus and Oxytropis and determine environmental influences on its growth and synthesis of swainsonine. 相似文献
13.
Maggi ME Mangeaud A Carpinella MC Ferrayoli CG Valladares GR Palacios SM 《Journal of chemical ecology》2005,31(7):1527-1536
Ethanolic extract of aerial parts of Artemisia annua L. and artemisinin were evaluated as anti-insect products. In a feeding deterrence assay on Epilachna paenulata Germ (Coleoptera: Coccinellidae) larvae, complete feeding rejection was observed at an extract concentration of 1.5 mg/cm2 on pumpkin leaf tissue. The same concentration produced a feeding inhibition of 87% in Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae). In a no-choice assay, both species ate less and gained less weight when fed on leaves treated with the extract. Complete mortality in E. paenulata and 50% mortality in S. eridania were observed with extract at 1.5 mg/cm2. Artemisinin exhibited a moderate antifeedant effect on E. paenulata and S. eridania at 0.03–0.375 mg/cm2. However, a strong effect on survival and body weight was observed when E. paenulata larvae were forced to feed on leaves treated at 0.03 and 0.075 mg/cm2. Artemisia annua ethanolic extract of aerial parts at 1.5 mg/cm2 showed no phytotoxic effect on pumpkin seedlings. 相似文献
14.
The distribution of FA between the sn-2 and sn-1,3 positions of TAG from Pistacia atlantica fruit oil of Algeria has been determined. Unsaturated FA showed a preference for the internal position. Linoleic and oleic
acids occurred predominantly in the sn-2 position with lesser amounts evenly distributed between the sn-1 and sn-3 positions, as generally found in vegetable oils. The oil was found to contain TAG that were trisaturated (0.93%), disaturated
(15.06%), monosaturated (44.64%), and triunsaturated (38.10%). The distribution of the TAG calculated using the lipase hydrolysis
technique is slightly different from that determined with HPLC. This is particularly true for trioleoyl and trilinoleoylglycerols.
In contrast, the agreement between theory and experiment is good for TAG containing two palmitoyl and one oleoyl, one oleoyl
and two linoleoyl, and one palmitoyl and two oleoyl chains. 相似文献
15.
Goldenseal (Hydrastis canadensis L.) is a popular medicinal plant distributed widely in North America. The rhizome, rootlets, and root hairs produce medicinally
active alkaloids. Berberine, one of the Hydrastis alkaloids, has shown antifungal activity. The influence of a combination of the major Hydrastis alkaloids on the plant rhizosphere fungal ecology has not been investigated. A bioassay was developed to study the effect
of goldenseal isoquinoline alkaloids on three Fusarium isolates, including the two species isolated from Hydrastis rhizosphere. The findings suggest that the Hydrastis root extract influences macroconidia germination, but that only the combined alkaloids—berberine, canadine, and hydrastine—appear
to synergistically stimulate production of the mycotoxin zearalenone in the Fusarium oxysporum isolate. The Hydrastis root rhizosphere effect provided a selective advantage to the Fusarium isolates closely associated with the root tissue in comparison with the Fusarium isolate that had never been exposed to Hydrastis. 相似文献
16.
Lipase-catalyzed interesterification between fish oil and medium-chain TAG has been investigated in a packedbed reactor with
a commercially immobilized enzyme. The enzyme, a Thermomyces lanuginosa lipase immobilized on silica by granulation (lipozyme TL IM; Novozymes A/S, Bagsvaerd, Denmark), has recently been developed
for fat modification. This study focuses on the new characteristics of the lipase in a packed-bed reactor when applied to
interesterification of TAG. The degree of reaction was strongly related to the flow rate (residence time) and temperature,
whereas formation of hydrolysis by-products (DAG and FFA) were only slightly affected by reaction conditions. The degree of
reaction reached equilibrium at 30–40 min residence time, and the most suitable temperature was 60°C or higher with respect
to the maximal degree of reaction. The lipase was stable in a 2-wk continuous operation without adjustment of water content
or activity of the column and the substrate mixture. 相似文献
17.
The aim of this work was to investigate the catalytic functions of a new immobilized Thermomyces lanuginosa lipase in interesterification and to optimize the conditions of interesterification for the production of human milk fat
substitutes (HMFS) containing n−3 PUFA by response surface methodology (RSM). Thermomyces lanuginosa lipase had an activity similar to that of immobilized Rhizomucor miehei lipase (Lipozyme RM IM) in the glycerolysis of sunflower oil, but the former had higher activity at a low reaction temperature
(5°C). Thermomyces lanuginosa lipase was found to have much lower catalytic activity than Lipozyme RM IM in the acidolysis of sunflower oil with caprylic
acid. However, the activity of T. lanuginosa lipase was only slightly lower than that of Lipozyme RM IM in the ester-ester exchange between tripalmitin (PPP) and the
ethyl esters of EPA and DHA (EE). For this reason, the new immobilized T. lanuginosa lipase was used to produce HMFS from PPP by interesterification with EE. The optimization of major parameters was conducted
with the assistante molar ratio of 5 (EE/PPP), a lipase load of 20 wt% (on substrates), and a reaction time of 20 h, with
acyl incorporation up to 42%. The model generated significantly represented real relationships between the response (incorporation)
and reaction parameters. 相似文献
18.
Our objective was to identify the sex pheromone of Lymantria bantaizana (Lepidoptera: Lymantriidae) whose larvae feed exclusively on walnut, Juglans spp., in China, and Japan. Coupled gas chromatographic–electroantennographic detection (GC-EAD) analyses of pheromone gland extracts revealed a single EAD-active component. Retention index calculations of this compound on four GC columns suggested that it was a methyl-branched octadecadiene with conjugated double bonds. In GC-EAD analyses of 2-methyloctadecenes, (Z)-2-methyl-7-octadecene and (E)-2-methyl-7-octadecene elicited the strongest antennal responses, suggesting that the double bond positions were at C7 and C9. In comparative GC-EAD analyses of pheromone gland extract and stereoselectively synthesized isomers (E,E; E,Z; Z,E; Z,Z) of 2-methyl-7,9-octadecadiene, the (E,Z)- and (Z,E)-isomer had retention times identical to that of the candidate pheromone, but only the latter isomer elicited strong EAD activity. Results of field experiments in Japan substantiated that (7Z,9E)-2-methyl-7,9-octadecadiene is the L. bantaizana sex pheromone, a compound previously unknown in the Lepidoptera. Detection surveys in North America for exotic Eurasian forest defoliators could include traps baited with the L. bantaizana pheromone. 相似文献
19.
Nigella sativa L. seed lipase isolated from defatted seeds was partially purified and used as catalyst in transesterification reactions.
Purification of an ammonium sulfate-precipitated sample (at 35% saturation, Nigella PL) by DEAE ion-exchange chromatography increased the specific activity from 13.9 to 156.7 U/mg protein. Nigella PL and Nigella CPL (the partially purified enzyme sample obtained by DEAE ion-exchange chromatography) catalyzed the transesterification of
vinyl acetate with octanol, with racemic sulcatol (6-methyl-5-hepten-2-ol), and with racemic trans-sobrerol (trans-p-menth-6-ene-2,8-diol) in different organic solvents. Both activity and enantioselectivity of the enzyme samples used for
these biotransformations were affected by the nature of the organic solvent. 相似文献
20.
The pinewood nematode (PWN), Bursaphelenchus xylophilus, the most important invasive species in pine forests of Asia, is transported to new pine hosts by beetles of the genus Monochamus. Third-stage dispersal juveniles (JIII) aggregate in pupal chambers around the vector as it matures. We demonstrated that the ratio of three terpenes (α-pinene,
β-pinene, and longifolene at 1:2.7:1.1) released by larval Monochamus alternatus strongly attract JIII, whereas the different ratio (1:0.1:0.01) of these three terpenes found in healthy xylem of Pinus massoniana attracts only the propagative stage (Jn) of the nematode. We suggest that the volatiles produced by the host plants could be the basis of a chemoecological relationship
between plant parasitic nematodes and their vector insects. Capture of JIII with terpene-baited trap tubes deployed for 2 hr in the field was demonstrated. This technique may lead to the development
of rapid sampling methodologies for use at either ports-of-entry or in the field. 相似文献