首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
Poly(l-lactide) degradation by Kibdelosporangium aridum   总被引:3,自引:0,他引:3  
A new poly(L-lactide) (PLA)-degrading actinomycete, Kibdelosporangium aridum, degraded more than 97 mg out of 100 mg added high molecular weight PLA film (Mn: 3.4 x 10(5)) within 14 d in liquid culture. L-Lactic acid, the monomeric degradation product of PLA, was totally assimilated by the strain. In solid culture, many distinct grooves formed by the morphology of filamentous microorganisms on the surface of a PLA film were observed by scanning electron microscopy.  相似文献   

2.
Aims: To develop an antimicrobial bottle coating effective at inhibiting the growth of Salmonella in liquid egg albumen (egg white) and reduce the risk of human Salmonellosis. Methods and Results: Four‐ounce glass jars were coated with a mixture of polylactic acid (PLA) polymer and antimicrobial compounds containing 100–500 μl allyl isothiocyanate (AIT), 250 mg nisin, 250 mg zinc oxide nanoparticles per jar or their combinations. The coated jars contained 100 ml of liquid egg white (LEW) inoculated with a three‐strain Salmonella enterica ssp. enterica cocktail at populations of 103 or 107 CFU ml?1 and stored at 10°C for 28 days. The PLA coating with 500 μl AIT completely inactivated 3 and 7 log CFU ml?1 of Salmonella after 7 and 21 days of storage, respectively. The PLA coating with 200 μl AIT in combination with 250 mg nisin reduced Salmonella populations to an undetectable level (<10 CFU ml?1) after 21 days of storage. Conclusions: PLA coatings containing AIT alone or in combination with nisin effectively inactivated salmonellae in LEW. Significance and Impact of the Study: This study demonstrated the commercial potential of applying the antimicrobial bottle coating method to liquid eggs and possibly other fluid food products.  相似文献   

3.
A high lysine-producing mutant of Lactobacillus plantarum (OG 261-5) derived from a wild type strain (OG 261) previously isolated from fermenting ogi was evaluated for nutritional improvement of ogi in a modified fermentation process. Results indicate that ogi obtained by fermentation with the pure culture of the mutant compared to traditional ogi increased in concentration of available lysine from 228.5 ± 12.0 mg/100 g to 525.1 ± 25.8 mg/100 g, tryptophan from 58.6 ± 8.0 mg/100 g to 114.3 ± 11.0 mg/100 g and tyrosine from 408.5 ± 13.7 mg/100 g to 4636.5 ± 11.3 mg/100 g. However, the contents of valine, leucine, isoleucine and phenylalanine were substantially reduced which may affect the protein quality of the modified ogi. The modified process shortened the period of traditional ogi production from five days to one by reducing the two-stage fermentation (i.e. soaking and souring stages) to a one-stage process and the total protein recovery was better compared to traditional ogi processing. There was no significant difference (P > 0.05) in organoleptic quality attributes of colour, flavour, and overall acceptability of ogi produced by the modified process and the traditional ogi.  相似文献   

4.
Short-term trials with the antioxidant thioctic acid (TA) appear to improve neuropathic symptoms in diabetic patients, but the long-term response remains to be established. Therefore, Type 1 and Type 2 diabetic patients with symptomatic polyneuropathy were randomly assigned to three treatment regimens: (1) 2 × 600 mg of TA (TA 1200), (2) 600 mg of TA plus placebo (PLA) (TA 600) or (3) placebo and placebo (PLA). A trometamol salt solution of TA of 1200 or 600 mg or PLA was intravenously administered once daily for five consecutive days before enrolling the patients in the oral treatment phase. The study was prospective, PLA-controlled, randomized, double-blind and conducted for two years. Severity of diabetic neuropathy was assessed by the Neuropathy Disability Score (NDS) and electrophysiological attributes of the sural (sensory nerve conduction velocity (SNCV), sensory nerve action potential (SNAP)) and the tibial (motor nerve conduction velocity (MNCV), motor nerve distal latency (MNDL)) nerve. Statistical analysis was performed after independent reviewers excluded all patients with highly variable data allowing a final analysis of 65 patients (TA 1200: n = 18, TA 600: n = 27; PLA: n = 20). At baseline no significant differences were noted between the groups regarding the demographic variables and peripheral nerve function parameters for these 65 patients. Statistically significant changes after 24 months between TA and PLA were observed (mean ± SD) for sural SNCV: +3.8 ± 4.2 m/s in TA 1200, +3.0 ± 3.0 m/s in TA 600, -0.1 ± 4.8 m/s in PLA (p < 0.05 for TA 1200 and TA 600 vs. PLA); sural SNAP: +0.6 ± 2.5 μV in TA 1200, +0.3 ± 1.4 μV in TA 600, -0.7 ± 1.5 μV in PLA (p = 0.076 for TA 1200 vs. PLA and p < 0.05 for TA 600 vs. PLA), and in tibial MNCV: +1.2 ± 3.8 m/s in TA 1200, -0.3 ± 5.2 m/s in TA 600, -1.5 ± 2.9 m/s in PLA (p < 0.05 for TA 1200 vs. PLA). No significant differences between the groups after 24 months were noted regarding the tibial MNDL and the NDS. We conclude that in a subgroup of patients after exclusion of patients with excessive test variability throughout the trial, TA appeared to have a beneficial effect on several attributes of nerve conduction.  相似文献   

5.
Efficient production of poly(l-lactide)(PLA)-degrading enzyme was achieved by addition of 0.1% (w/v) silk fibroin powder into a liquid culture medium of an actinomycete, Amycolatopsis orientalis, without other complex nitrogen sources, such as yeast extract and peptone. Scaled-up production of the enzyme in a 5-l jar fermenter showed the possibility of producing this enzyme on an industrial scale at low production cost. The extracellular PLA-degrading enzyme showed potent degrading activity, which is effective for biological recycling of PLA, i.e., 2,000 mg/l of PLA powder was completely degraded within 8 h at 40°C using 20 mg/l purified enzyme. An optically active l-lactic acid with 600 mg/l was obtained as degradation product of PLA without undesirable racemization.  相似文献   

6.
The fermentation process for a poly (L-lactide) (PLA)-degrading enzyme production by a newly isolate of thermophilic PLA-degrading Actinomadura sp. T16-1 was investigated. The strain produced 33.9 U/mL of enzyme activity after cultivation at 50°C under shaking of 150 rpm for 96 h in a medium consisting of (w/v) 0.05% PLA film, 0.2% gelatin, 0.4% (NH4)2SO4, 0.4% K2HPO4, 0.2 % KH2PO4, and 0.02% MgSO4 · 7H2O. The optimal concentration of PLA film and gelatin obtained by response surface methodology (RSM) for the highest production of PLA-degrading enzyme was 0.035% (w/v) and 0.238% (w/v), respectively. Under these conditions, the model predicted 40.4 U/mL of PLA-degrading activity and the verification of the optimization showed 44.6 U/mL of PLA-degrading enzymatic activity in the flasks experiment. The maximum PLA-degrading activity reached 150 U/mL within 72 h cultivation in the 3-L airlift fermenter.  相似文献   

7.
Phospholipase A2 (PLA2) is a key component of the inflammatory process because of its role in the generation of eicosanoids and platelet-activating factor (PAF). Manipulation of PLA2 activity offers a novel therapeutic approach for the development of antiinflammatory agents; however, there is a need for a suitable in vivo model. Injection of 1 microgram of snake venom PLA2 (A. piscivorus piscivorus, D-49) into the mouse hind footpad produced a significant three- to four-fold rise in paw edema within 10 min, compared to the saline control. Edema formation depended on enzyme concentration and appeared specific for PLA2 since edema was negated by enzyme pretreatment with p-bromophenacyl bromide, a nonspecific PLA2 inhibitor. Moreover, injection of a protein such as bovine serum albumin did not result in significant edema. Coinjection of phenidone (lipoxygenase inhibitor, 50 micrograms), indomethacin (cyclooxygenase inhibitor, 50 micrograms), cyproheptadine (antihistamine/antiserotonin, 50 micrograms), aristolochic acid (putative PLA2 inhibitor, 100 micrograms), or kadsurenone (PAF antagonist, 50 micrograms) with PLA2 (1 microgram/paw) resulted in partial reduction (44.5, 34.2, 54.7, 64, and 50% inhibition, respectively) of edema formation. Oral administration of cyproheptadine (10 mg/kg), indomethacin (10 mg/kg), BW 755c (100 mg/kg), or dexamethasone (1 mg/kg) 1-3 h before challenge also decreased PLA2-induced edema (63.0, 30.1, 47.8, or 62.5% inhibition, respectively). The data suggest that mouse paw edema resulting from PLA2 injection is a multicomponent event, influenced by both autacoids and lipid mediators of inflammation.  相似文献   

8.
Abstract

Aim: The main purpose of this work was to develop new protocols for high yield purification of secretory phospholipase A2 (PLA2) and to investigate its biophysical properties.

Materials and methods: We have used a Pichia pastoris expression system for PLA2 expression and two-stage chromatography for its purification. The biophysical properties of PLA2 were investigated by circular dichroism.

Results: A scalable method for high yield purification of recombinant Streptomyces violaceruber PLA2 was developed. The PLA2 from S. violaceruber was expressed in the methylotrophic yeast P. pastoris. Functional active phospholipase A2 with specific activity 73?U/mg was purified with a concentration of at least 3?mg/mL. The role of different divalent ions in PLA2 thermostability were evaluated. Ca2+ and Ba2+ ions significantly increased thermostability of the enzyme.  相似文献   

9.
【目的】通过体外静态模拟瘤胃发酵法研究溶菌酶对瘤胃发酵、甲烷生成及微生物菌群结构的影响。【方法】采用单因素多水平试验设计,溶菌酶添加水平分别为0(L-0,对照组)、0.1 mg/100 m L(L-0.1)、1 mg/100 m L(L-1)、10 mg/100 m L(L-10)和100 mg/100 m L(L-100),定时测定产气量和甲烷产量,培养24 h后,发酵液用于发酵参数和微生物菌群数量的q PCR测定,其中L-0、L-1和L-100三个组发酵液同时进行16S r RNA基因Illumina高通量测序。【结果】与对照组相比,低剂量溶菌酶添加(L-0.1组)不影响甲烷产量、氨氮浓度、干物质消失率、有机物消失率和总挥发性脂肪酸等瘤胃发酵参数(P0.05);随着剂量提高,L-1处理组甲烷产量、氨氮浓度显著降低(P0.05),丙酸浓度显著增加(P0.05),并且干物质消失率、有机物消失率和总挥发性脂肪酸不受影响(P0.05);而较高剂量组(L-10和L-100组)虽然甲烷产量显著降低,丙酸浓度显著增加(P0.05),但干物质消失率和有机物消失率也显著降低(P0.05)。q PCR结果显示高剂量组(L-100组)总菌、原虫、甲烷菌数量与对照组相比显著降低(P0.05),而L-0.1、L-1和L-10组总菌、真菌和原虫数量与对照组相比均无显著变化(P0.05)。高通量测序主成分分析(PCA)显示对照组与溶菌酶添加组间瘤胃细菌组成的明显区分,说明添加溶菌酶显著改变了瘤胃细菌菌群结构。溶菌酶通过增加月形单胞菌和琥珀酸弧菌等丙酸生成菌的相对丰度,使更多的氢被用于生成丙酸,导致甲烷产量降低;溶菌酶可抑制普雷沃氏菌和拟杆菌属等蛋白降解菌的生长,进而减少蛋白质过度降解,降低氨氮浓度。【结论】添加适宜浓度(1 mg/100 m L)的溶菌酶可通过调控瘤胃微生态改变瘤胃发酵模式,降低瘤胃甲烷和氨的生成,短期内并不影响饲料消化。  相似文献   

10.
Abstract

Pinolenic acid (PLA) enrichment as an ethyl ester from pine nut oil was successfully accomplished in a batch reactor by lipase-catalyzed ethanolysis using Novozym 435 lipase from Candida antarctica as a biocatalyst. PLA is predominantly an sn-3 substituent of the pine nut oil triacylglycerol (TAG), where it accounts for about 39 mol% of the fatty acids esterified at that position. In the presence of ethanol, Novozym 435 exhibited sn-3 regiospecificity with respect to the TAG of pine nut oil. The effect of the molar ratio of reactants on PLA enrichment by ethanolysis was investigated. The molar ratios of pine nut oil to ethanol were varied from 1:20 to 1:100. A fatty acid ethyl ester (FAEE) fraction with higher PLA content was obtained in the early stage of the reaction, although the yield of PLA was small. However, the PLA content of the FAEEs decreased with increasing reaction time, while the yield of PLA increased. The molar ratio of pine nut oil to ethanol that produced the optimum content and yield of PLA in FAEEs was 1:80.  相似文献   

11.
Li X  Jiang B  Pan B 《Biotechnology letters》2007,29(4):593-597
Phenyllactic acid (PLA) is a novel antimicrobial compound derived from phenylalanine (Phe). Lactobacillus sp. SK007, having high PLA-producing ability, was isolated from Chinese traditional pickles. When 6.1 mM phenylpyruvic acid (PPA) was used to replace Phe as substrate at the same concentration, PLA production increased 14-fold and the fermentation time decreased from 72 h to 24 h with growing cells. With resting cells, however, 6.8 mM PLA could be obtained as optimal yield using the following conditions: 12 mM PPA, 55 mM glucose, pH 7.5, 35°C and 4 h.  相似文献   

12.
A series of fluorine and hydroxyl containing jasmonate derivatives, which were chemically synthesized in our institute, were investigated for their effects on the biosynthesis and heterogeneity of ginsenosides in suspension cultures ofPanax notoginseng cells. Compared to the control (without addition of elicitors), 100 μM of each of the jasmonate was added on day 4 to the suspension cultures ofP. notoginseng cells. It was observed that, jasmonates greatly enhanced the ginsenoside content and the ratio of Rb group to Rg group (i.e. (Rb1+Rd)/(Rg1+Re)) in theP. notoginseng cells. Some of the synthetic jasmonates, such as pentafluoropropyl jasmonate (PFPJA), 2-hydroxyethyl jasmonate (HEJA) and 2-hydroxyethoxyethyl jasmonate (HEEJA), could promote the ginsenoside content to 2.55±0.11, 3.65±0.13 and 2.94±0.06 mg/100 mg DW, respectively, compared to that of 0.64±0.06 mg/100 mg DW for the control and 2.17±0.04 mg/100 mg DW by the commercially available methyl jasmonate (MJA); and they could change the respective Rb: Rg ratio to 1.60±0.04, 1.87±0.01 and 1.56±0.05, compared to that of 0.47±0.01 for the control and 1.42±0.06 by MJA. The results suggest that suitable esterification of MJA with fluorine or hydroxyl group could increase the elicitation activity to induce plant secondary metabolism. The information obtained from this study is useful for hyper-production of heterogeneous products by plant cell cultures.  相似文献   

13.
The shoot apical meristem (SAM) produces lateral organs in a regular spacing (phyllotaxy) and at a regular interval (phyllochron) during the vegetative phase. In a Dissociation (Ds) insertion rice population, we identified a mutant, compact shoot and leafy head 1 (csl1), which produced massive number of leaves (∼70) during the vegetative phase. In csl1, the transition from the vegetative to the reproductive phase was delayed by about 2 months under long-day conditions. With a reduced leaf size and severe dwarfism, csl1 failed to produce a normal panicle after the transition to reproductive growth. Instead, it produced a leafy panicle, in which all primary rachis-branches were converted to vegetative shoots. Phenotypically csl1 resembled pla mutants in short plastochron but was more severe in the conversion of the reproductive organs to vegetative organs. In addition, neither the expression nor the coding region of PLA1 or PLA2 was affected in csl1. csl1 is most likely a dominant mutation because no mutant segregant was observed in progeny of 67 siblings of the csl1 mutant. CSL1 may represent a novel gene, which functions downstream of PLA1 and/or PLA2, or alternatively functions in a separate pathway, involved in the regulation of leaf initiation and developmental transition via plant hormones or other mobile signals.  相似文献   

14.
Broussonetia papyrifera is well-known for its bark fibers, which are used for making paper, cloth, rope etc. This is the first report of a successful genetic transformation protocol for B. papyrifera using Agrobacterium tumefaciens. Callus was initiated at a frequency of about 100% for both leaf and petiole explants. Shoots formed on these calli with a success rate of almost 100%, with 14.08 and 8.36 shoots regenerating from leave-derived and petiole-derived callus, respectively. For genetic transformation, leaf explants of B. papyrifera were incubated with A. tumefaciens strain LBA4404 harboring the binary vector pCAMBIA 1301 which contains the hpt gene as a selectable marker for hygromycin resistance and an intron-containing β-glucuronidase gene (gus-int) as a reporter gene. Following co-cultivation, leaf explants were cultured on Murashige and Skoog (Physiol Plant 15:473, 1962) (MS) medium supplemented with 1.5 mg l−1 benzyladenine (BA) and 0.05 mg l−1 indole-3-butyric acid (IBA) (CI medium) containing 5 mg l−1 hygromycin and 500 mg l−1 cefotaxime, in the dark. Hygromycin-resistant calli were induced from leaf explants 3 weeks thereafter. Regenerating shoots were obtained after transfer of the calli onto MS medium supplemented with 1.5 mg l−1 BA, 0.05 mg l−1 IBA, and 0.5 mg l−1 gibberellic acid (GA3) (SI medium), 5 mg l−1 hygromycin and 250 mg l−1 cefotaxime under fluorescent light. Finally, shoots were rooted on half strength MS medium (1/2 MS) supplemented with 10 mg l−1 hygromycin. Transgene incorporation and expression was confirmed by PCR, Southern hybridisation and histochemical GUS assay. Using this protocol, transgenic B. papyrifera plants containing desirable new genes can be obtained in approximately 3 months with a transformation frequency as high as 44%.  相似文献   

15.
The Biodegradation capabilities of six selected cyanobacterial species for fluometuron, a phenylurea herbicide, as well as its inhibitory effect on chlorophyll a content were investigated. The selected species (three strains of Microcystis aeruginosa, Anabaena cylindrica, A. flos-aquae and A. spiroides) were subjected to three elevated concentrations of fluometuron (0.14, 0.7 and 1.4 mg/ml) for different exposure times (1–5 days). Results revealed that biodegradation of fluometuron is species-dependent and positively correlated with the exposure time, reaching maximum efficiency after 5 days at all the investigated concentrations. All the species tested showed generally great ability to degrade the compound even at the highest concentration with specific variations among them. Biodegradation efficiencies of fluometuron by the selected species were in the following ranges; 39.2–99.9; 87.5–100; and 93.2–100 at 0.14; 0.7 and 1.4 mg fluometuron/ml respectively. It was noticed that the gradual increase in the pesticide concentration enhances its biodegradability by the selected algal species. Variations according to species as well as exposure time were discussed. The highest fluometuron concentration (1.4 mg/l) showed the highest inhibition of chlorophyll a content in the tested species and toxicity was also species- and time-dependent.  相似文献   

16.
A protocol for multiple shoot induction from cotyledonary node explants of Terminalia chebula Retz. has been developed. Germination frequency of embryos (up to 100 %) was obtained on Murashige and Skoog (MS) medium supplemented with 0.5 mg dm–3 gibberellic acid (GA3). Maximum number of shoots (6.4 shoots per cotyledonary node) was obtained on half-strength MS + 0.3 mg dm–3 GA3+ 1.0 mg dm–3 indole-3-butyric acid (IBA) + 10.0 mg dm–3 benzylaminopurine (BAP) after 4 weeks of culture. When the cotyledonary nodes along with the axillary shoot buds were allowed to grow in the same medium upto 19.2 shoots were obtained after 8 – 9 weeks. Best rooting (100 %, 5.5 roots per shoot) was observed when shoots were excised and transferred to half-strength MS medium containing 1.0 mg dm–3 IBA + 1 % mannitol and 1.5 % sucrose. Survival of rooted plants in vivo was low (35 – 40 %) when they were directly transferred to soil in glasshouse. However, transfer to soil with MS nutrients and 1.0 mg dm–3 IBA in culture room for a minimum duration of 2 weeks increased the survival percentage of plants to 100 %.  相似文献   

17.
Cymbopogon winterianus (Poaceae) is used for its analgesic, anxiolytic and anticonvulsant properties in Brazilian folk medicine. This report aimed to perform phythochemical screening and to investigate the possible anticonvulsant effects of the essential oil (EO) from fresh leaves of C. winterianus in different models of epilepsy. The phytochemical analysis of EO showed presence of geraniol (40.06%), citronellal (27.44%) and citronellol (10.45%) as the main compounds. A behavioral screening demonstrated that EO (100, 200 and 400 mg/kg; ip) caused depressant activity on CNS. When administered concurrently, EO (200 and 400 mg/kg, ip) significantly reduced the number of animals that exhibited PTZ- and PIC-induced seizures in 50% of the experimental animals (p<0.05). Additionally, EO (100, 200 and 400 mg/kg, ip) significantly increased (p<0.05) the latencies of clonic seizures induced by STR. Our results demonstrated a possible activity anticonvulsant of the EO.  相似文献   

18.
Efficient transformation of leaf disc-derived callus of Codonopsis lanceolata was obtained using Agrobacterium tumefaciens strain LBA4404 harboring a binary vector, pYBI121, that carries the neomycin phosphotransferase (npt II) gene as a selectable marker. The green shoots recovered from agroinfected explants on selection medium (containing 0.1 mg/l α-naphthaleneacetic acid (NAA), 1 mg/l 6-benzylaminopurine (BAP), 100 mg/l kanamycin, and 250 mg/l cefotaxime) were rooted on Murashige and Skoog (MS) medium supplemented with 2 mg/l IBA and 10 mg/l kanamycin. To optimize the transformation conditions, several factors were assessed, including the co-cultivation period, the duration of pre- and post-culture in darkness and light, the kanamycin concentration, and the Agrobacterium densities. We produced transgenic Codonopsis lanceolata overexpressing γ-tocopherol methyltransferase (γ-TMT) by this protocol. Moreover, the α-tocopherol content of the plants was enhanced by the overexpression of this gene. Bimal Kumar Ghimire and Eun Soo Seong contributed equally to this work.  相似文献   

19.
Lovastatin suppresses its own synthesis in the microfungus Aspergillus terreus. The inhibitory effect was documented by spiking identical batch cultures with pure lovastatin (0, 50, 100 and 250 mg/l) 24 h after initiation from spores.  相似文献   

20.
A total of 57 samples of feedstuffs commonly used for animal nutrition in Colombia (corn, soybean, sorghum, cottonseed meal, sunflower seed meal, wheat middlings and rice) were analyzed for Fusarium contamination. Fusarium fungi were identified at species level by means of conventional methods and the ability to produce fumonisins of the most prevailing species was determined. A total of 41 of the feedstuffs analyzed (71.9%) were found to contain Fusarium spp. Most contaminated substrates were corn (100%), cottonseed meal (100%), sorghum (80%), and soybean (80%). Wheat middlings and rice showed lower levels of contamination (40% and 20%, respectively), while no Fusarium spp. could be isolated from sunflower seed meal. The most prevalent species of Fusarium isolated were F. verticilliodes (70.8%), F.␣proliferatum (25.0%), and F. subglutinans (4.2%). All of them correspond to section Liseola.Production of fumonisins on corn by the isolated Fusarium was screened through liquid chromatography. Almost all strains of F. verticilliodes (97.1%) produced FB1 (5.6–25,846.4 mg/kg) and FB2 (3.4–7507.5 mg/kg). Similarly, almost all strains of F.␣proliferatum (91.7%) produced fumonisins but at lower levels than F.␣verticilliodes (FB1 from 6.9 to 3885.0 mg/kg, and FB2 from 34.3 to 373.8 mg/kg), while F. subglutinans did not produce these toxins. This is the first study in Colombia describing toxigenic Fusarium isolates from␣animal feedstuffs.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号