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1.
Industrial production of L ‐lactic acid, which in polymerized form as poly‐lactic acid is widely used as a biodegradable plastic, has been attracting world‐wide attention. By genetic engineering we constructed a strain of the Crabtree‐negative yeast Candida boidinii that efficiently produced a large amount of L ‐lactic acid. The alcohol fermentation pathway of C. boidinii was altered by disruption of the PDC1 gene encoding pyruvate decarboxylase, resulting in an ethanol production that was reduced to 17% of the wild‐type strain. The alcohol fermentation pathway of the PDC1 deletion strain was then successfully utilized for the synthesis of L ‐lactic acid by placing the bovine L ‐lactate dehydrogenase‐encoding gene under the control of the PDC1 promoter by targeted integration. Optimizing the conditions for batch culture in a 5 l jar‐fermenter resulted in an L ‐lactic acid production reaching 85.9 g/l within 48 h. This productivity (1.79 g/l/h) is the highest thus far reported for L ‐lactic acid‐producing yeasts. DDBJ/EMBL/GenBank nucleotide database with Accession Nos. AB440630 and AB440631. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

2.
Kappa‐casein (κ‐CN) is the subtype of casein protein, an important constituent of bovine milk protein. The current study was undertaken to investigate the genetic polymorphism in κ‐CN gene of Nili‐ravi buffalo, Achai and Sahiwal cattle of Pakistan using polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) technique. The Nili‐ravi buffalo was found to be monomorphic (genotype BB only) for κ‐CN gene. Achai cattle were polymorphic for κ‐CN (having three genotypes AA, AB and BB) with a frequency of 0.70, 0.18 and 0.12, respectively, while in Sahiwal cattle, both the genotypes AA and AB were found with genotypic frequencies of 0.92 and 0.08, respectively. The presence of genotype BB in Achai cattle is surprising as it is absent in most of the cattle breeds worldwide.  相似文献   

3.
The purpose of this study was to investigate pre‐selected pediococci for potential probiotic use in Iberian dry‐fermented sausages. A total of twelve strains isolated from Iberian dry‐fermented sausages and pig faeces were evaluated according to safety and functional characteristics including biogenic amines and d ‐lactic acid production, antibiotic susceptibility, cell adhesion and antimicrobial activity against food‐borne pathogens. The strain P. acidilactici SP979 was able to establish itself and compete with enteropathogens such as Salmonella choleraesuis on the intestinal epithelium and an inhibition of such pathogenic bacteria as Listeria monocytogenes and Staphylococcus aureus in vitro. This strain was also considered safe to be used with regard to its void aminogenic potential, low d ‐lactic acid production and antibiotic resistance pattern; being identified as a potential probiotic meat starter culture suitable for manufacture of dry‐fermented Iberian sausages.  相似文献   

4.
A number of α-hydroxy acids, including glycolic, lactic ( l (+) and d (–) forms) citric, hydroxybutyric and malic acids, were evaluated for their effects on various skin properties at concentrations of 0.5–1.15 m . The acids were evaluated for their stinging potential on sensitive skin, the ability to increase skin cell renewal, and their ability to improve moisture content and reduce lines and wrinkles over a six-week period. Results indicated that lactic l (+) and glycolic were the most effective acids when tested at equimolar concentrations. Both materials were less irritating than the d (–) lactic acid form and the other acids tested. Even though with long-term use both d (–) and l (+) lactic acid and glycolic acid produced comparative improvements in skin hydration and lines and wrinkle improvement, the l (+) form of lactic acid did so with fewer consumer complaints than any of the other acids tested. When the concentration of lactic and glycolic acids was increased to more than 1.5 m a greater difference in irritation potential was observed with respect to stinging, with the l (+) form of lactic acid being less irritating than glycolic acid and the d (–) form. Our results suggest that l (+) and d (–) lactic acid and glycolic acid are the two most effective materials for developing α-hydroxy acid products. Lactic acid has a slight technical advantage over glycolic acid. Both l (+) and the d (–) forms are better moisturizers when fully or partially neutralized. Moreover the l (+) form is also less irritating than d (–) and glycolic acid. Other acids such as citric, malic, and hydroxybutyric acids appear to be less effective materials but may be useful additions to lactic or glycolic acid mixes.  相似文献   

5.
Fermented plant beverages (FPB) with a high content of desirable principle components are served as functional foods from several years. Hericium erinaceus is famous for its antimicrobial, antioxidant, antihypertensive and antidiabetic nature. Accordingly, the current study was aimed to produce fermented H. erinaceus juice with a high content of L‐glutamine (Gln) and L‐glutamic acid (GA) through lactic acid bacteria (LAB) isolated from fermented Thai foods. LAB isolates were screened and identified the potent protease‐producing bacteria Enterococcus faecalis (G414/1) that facilitate the production of Gln and GA through protein hydrolysis. Box–Behnken design (BBD) and response surface methodology (RSM) were adapted for the optimisation of conditions for the increased production of Gln and GA during fermentation of H. erinaceus. We succeeded with an optimum concentration of cofactor (CaCl2), pH and temperature for improved protease activity and subsequent Gln and GA production. The ability of isolated E. faecalis strain to produce Gln and GA was demonstrated in this study. Further, upstream processes like strain improvement and media optimisation will direct the way to produce enriched H. erinaceus based FPB.  相似文献   

6.
The International Agency for Research on Cancer (IRAC) has classified 4(5)‐methylimidazole (4‐MeI) as a group 2B possible human carcinogen. Thus, how 4‐MeI forms in a d ‐glucose (Glu) amino acids (AA) model system is important, as it is how browning is affected. An aqueous solution of Glu was mixed individually in equimolar amounts at 3 concentrations (0.05, 0.1, and 0.15 M) with aqueous solutions of l ‐Alanine (Ala), l ‐Arginine (Arg), Glycine (Gly), l ‐Lysine (Lys), and l ‐Serine (Ser). The Glu‐AA mixtures were reacted at 60, 120, and 160 °C for 1 h. The 4‐MeI levels were measured by gas chromatography‐mass spectrometry after derivatization with isobutylchloroformate. No 4‐MeI was formed at 60 °C for any treatment combination; however, at 120 °C and 0.05 M, Glu‐Arg and Glu‐Lys produced 0.13 and 0.14 mg/kg of 4‐MeI. At 160 °C and 0.05 M all treatment combinations formed 4‐MeI. At 160 °C and 0.15 M, the observed levels of Glu‐Ala, Glu‐Arg, Glu‐Gly, Glu‐Lys, and Glu‐Ser were 0.21, 1.00, 0.15, 0.22, and 0.16 mg/kg. The AA type, reactant concentrations, and temperature significantly affected (P < 0.001) formation of 4‐MeI as well as browning. Glu‐Lys treatment in all combinations produced the most browning, but Glu‐Arg produced the most 4‐MeI. This method showed that foods processed using low temperatures may have reduced levels of 4‐MeI.  相似文献   

7.
Brewer's spent grain (BSG) hydrolysates were used for l ‐(+)‐lactic acid (LA) fermentation by Lactobacillus rhamnosus ATCC 7469. The aim of this study was to evaluate fed‐batch LA fermentation of BSG hydrolysate with the addition of glucose, glucose and yeast extract, and wort during LA fermentation and its effect on fermentation parameters such as LA concentration, its volumetric productivity and yield, and L. rhamnosus cell viability. The highest LA yield, volumetric productivity and concentration of 93.3%, 2.0 g/L/h, and 116.1 g/L, respectively, were achieved with glucose and yeast extract addition during fermentation. In fed‐batch fermentation with glucose and yeast extract addition significantly higher LA concentration, yield and volumetric productivity (by 194.8; 2.2, and 20.7%, respectively) were achieved compared with batch fermentation. The results indicated that fed‐batch fermentation could be used to increase LA fermentation efficiency. Copyright © 2017 The Institute of Brewing & Distilling  相似文献   

8.
Extracts of several plants possess antithrombotic effects. Herein, we examined the antithrombotic effects of different extracts of Artemisia princeps Pampanini prepared using distilled water, hot distilled water, 70% ethanol, or subcritical water. The antithrombotic effects were determined using a co‐culture system consisting of tumor necrosis factor‐alpha (TNF‐α)‐treated EA.hy926 cells and THP‐1 cells. In addition, the coagulation time of plasma collected from healthy volunteers was evaluated in terms of the prothrombin time and activated partial thromboplastin time. A carotid arterial thrombosis model was induced by ferric chloride in Sprague Dawley rats. The rats were treated with either sterile water or three different doses of the subcritical water extract for 2 weeks. The thrombus weight, gene expression of cell adhesion molecules, and histological characteristics were assessed. The results of in vitro studies revealed a significant inhibition in the adhesion of monocytes to EA.hy926 cells stimulated by TNF‐α in the subcritical water extract‐treated group. We also observed considerable suppression of the occlusion and mRNA expression of cell adhesion molecules in the in vivo experiments. This study suggests that Artemisia princeps Pampanini may have the potential to improve blood coagulation.  相似文献   

9.
In previously studies, we showed that tumor necrosis factor‐α (TNF‐α), a cytokine involved in a variety of biologically important events, is partially involved in the effects of conjugated linoleic acid (CLA). In this report, we further tested the effects of individual CLA isomers on serum TNF‐α concentration along with other biological markers in mice. The animals were fed experimental diets (control, 0.5% CLA‐mixed isomer, 0.25% cis‐9,trans‐11 CLA or 0.25% trans‐10,cis‐12 CLA) for 5 days and were then challenged with endotoxin. Both cis‐9,trans‐11 and trans‐10,cis‐12 CLA isomers reduced serum TNF‐α levels compared to control. CLA had no effect on the other biological markers examined. These results suggest possible early involvement of CLA in immune and/or inflammatory responses, followed by reduction of body fat. Its effect on TNF‐α helps explain in part how CLA modulates other biological functions such as immune response, insulin responses, atherosclerosis and cancer.  相似文献   

10.
Two experiments were carried out to study the influence of storage time, glucose and urea additions ( Experiment 1 ) and lactic acid bacteria inoculation with and without glucose addition ( Experiment 2 ) on the production of lactate isomers and fermentation quality of guineagrass (Panicum maximum Jacq) silage. All silages in both experiments were well preserved, as indicated by lower pH and little or no butyric acid. In Experiment 1 , addition of glucose or urea did not significantly affect the pH of silages (P > 0.05). Urea addition tended to reduce acetic acid content and greatly increased NH3 − N content. L (+)‐Lactic acid was produced predominantly in the first 3 days of ensiling, but D (−)‐lactic acid increased gradually until 1 month after ensiling. Thereafter all silages became stable. In Experiment 2 , inoculation of Lactobacillus casei or L rhamnosus with or without glucose reduced D (−)‐lactic acid and increased L (+)‐lactic acid of silages. The proportions of L (+)‐lactic acid in these silages were higher than 80% of total lactic acid. L plantarum alone or in combination with glucose promoted D (−)‐lactic acid production and decreased the proportion of L (+)‐lactic acid. Glucose addition alone tended to reduce the proportion of L (+)‐lactic acid in both experiments. © 2000 Society of Chemical Industry  相似文献   

11.
Sesame lignans have antioxidative and anti‐inflammatory properties. We focused on the effects of the lignans sesamin and sesamol on the expression of endothelial‐leukocyte adhesion molecules in tumor necrosis factor‐α (TNF‐α)‐treated human aortic endothelial cells (HAECs). When HAECs were pretreated with sesamin (10 or 100 μM), the TNF‐α‐induced expression of intercellular cell adhesion molecule‐1 (ICAM‐1) was significantly reduced (35 or 70% decrease, respectively) by Western blotting. Sesamol was less effective at inhibiting ICAM‐1 expression (30% decrease at 100 μM). Sesamin and sesamol reduced the marked TNF‐α‐induced increase in human antigen R (HuR) translocation and the interaction between HuR and the 3'UTR of ICAM‐1 mRNA. Both significantly reduced the binding of monocytes to TNF‐α‐stimulated HAECs. Sesamin significantly attenuated TNF‐α‐induced ICAM‐1 expression and cell adhesion by downregulation of extracellular signal‐regulated kinase 1/2 and p38. Furthermore, in vivo, sesamin attenuated intimal thickening and ICAM‐1 expression seen in aortas of apolipoprotein‐E‐deficient mice. Taken together, these data suggest that sesamin inhibits TNF‐α‐induced extracellular signal‐regulated kinase/p38 phosphorylation, nuclear translocation of NF‐κB p65, cytoplasmic translocalization of HuR and thereby suppresses ICAM‐1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that sesamin may prevent the development of atherosclerosis and inflammatory responses.  相似文献   

12.
Three bovine casein peptides, ie LLY, PGPIPN and TTMPLW, were used to investigate their effects on cytokine (TNF‐α and IL‐6) production and nitric oxide (NO) release by murine bone marrow macrophages (BMMs). The results showed that these peptides alone were incapable of stimulating cytokine production or NO release in naive or IFN‐γ‐primed BMMs. However, when BMMs were co‐incubated with the peptides at a concentration of 1.0 µM and lipopolysaccharide (LPS; 100 ng ml−1), an augmentative effect on TNF‐α, IL‐6 and NO production was observed. Of the three peptides, TTMPLW had the greatest augmentative effect on NO production by LPS‐stimulated BMMs and induced the highest amount of TNF‐α production at a concentration of 1.0 µM . All the peptides at a concentration of 1.0 µM stimulated IL‐6 production by BMMs. TNF‐α was neutralised by anti‐TNF‐α monoclonal antibody and the release of NO was reduced by about 33.3% (p < 0.01). These results demonstrate that bovine casein peptides can co‐stimulate naive macrophages with LPS for proinflammatory cytokine production and NO release and may play a role in host defence against pathogens. © 2000 Society of Chemical Industry  相似文献   

13.
In order to study the human intestinal transit of flavan‐3‐ol C‐glycosides, several C‐glycosyl derivatives were prepared by non‐enzymatic reaction of (+)‐catechin with α‐D ‐glucose, α‐D ‐galactose and α‐D ‐rhamnose, respectively. In contrast to literature data, we propose that the reaction mechanism proceeds in analogy to the rearrangement of flavan‐3‐ols during epimerization under alkaline conditions. Four of the 12 synthesized flavan‐3‐ol C‐glycosides were incubated under aerobic conditions at 37°C using saliva (2 min) and simulated gastric juice (3 h). To simulate human intestine, the C‐glycosides were also incubated under anaerobic conditions at 37°C both in human ileostomy fluid (10 h) and colostomy fluid (24 h), respectively. The flavan‐3‐ol C‐glycosides under study, i.e. (+)‐epicatechin 8‐C‐β‐D ‐glucopyranoside (1a), (+)‐epicatechin 6‐C‐β‐D ‐glucopyranoside (1d), (+)‐catechin 6‐C‐β‐D ‐galactopyranoside (2b), (+)‐catechin 6‐C‐β‐D ‐rhamnopyranoside (3b) were analyzed in the incubation samples by HPLC‐DAD and HPLC‐DAD‐MS/MS. They were found to be stable in the course of incubation in saliva, simulated gastric juice and ileostomy fluid and underwent degradation in colostomy fluid. While the 6‐C‐β‐D ‐glucopyranoside 1d was completely metabolized between 2 and 4 h, decomposition of the 6‐C‐β‐D ‐galactopyranoside 2b reached only 16±2% within 4 h of incubation. Linear degradation rates of 1d and 2b in colostomy fluid differed significantly. As microbial metabolism of flavan‐3‐ols is known not to be influenced by the stereochemistry of the aglycon, varying degradation rates are ascribed to the effect of the sugar moiety. Based on these results we assume that flavan‐3‐ol C‐glycosides pass through the upper gastrointestinal tract (oral cavity, stomach and small intestine) unmodified and are then metabolized by the colonic microflora.  相似文献   

14.
In this study, prolactin gene polymorphism was investigated in Nili‐ Ravi buffaloes, Sahiwal and Achai cattle breeds, 100 per group, using polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) technique. Only genotype GG was observed in the case of Nili‐Ravi buffaloes. In Sahiwal and Achai cattle, three genotypes were found, AA, AG and GG: the frequency of these genotypes were 72%, 18% and 10% in Sahiwal cattle and 44%, 34% and 22% in Achai cattle, respectively. The frequency of genotype AA was found to be higher in both cattle breeds. Results of chi‐square test at P < 0.05 revealed that animals of Achai cattle were in Hardy–Weinberg equilibrium, whereas Sahiwal cattle were found to be deviating.  相似文献   

15.
The formation and degradation of N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)proline, derived from the secondary amine Maillard reaction in xylose‐amino acid model solutions, were detailed in this study. The identification and quantitative analysis of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline were carried out using high‐performance anion‐exchange chromatography and high‐performance liquid chromatography. The formation of intermediate and advanced products derived from N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline was also tested using an UV‐Vis spectrophotometer to gain a better comparing of the degradation process of the two important Maillard reaction products using thermal treatment. Results showed that the degradation of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine was more significant than N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline. Moreover, xylose was tested in the degradation products of both N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline, which indicated that the degradation of N‐substituted 1‐amino‐1‐deoxyketoses was a reversible reaction to form reducing sugar.  相似文献   

16.
Protective effects of caffeic acid (CA) and ellagic acid (EA) in kidney of diabetic mice were examined. CA or EA at 2.5 and 5% was mixed in diet and supplied to diabetic mice for 12 wk. Results showed that the intake of CA or EA increased renal content of these compounds, alleviated body weight loss, decreased urine output, increased plasma insulin and decreased blood glucose levels at weeks 6 and 12 (p<0.05). The intake of these compounds dose dependently reduced plasma blood urea nitrogen and elevated creatinine clearance (p<0.05). CA or EA at 5% significantly decreased the levels of plasma HbA1c, urinary glycated albumin, renal carboxymethyllysine, pentosidine, sorbitol and fructose (p<0.05), and significantly diminished renal activity of aldose reductase and sorbitol dehydrogenase, as well as suppressed renal aldose reductase mRNA expression (p<0.05). CA or EA dose dependently lowered renal levels of IL‐6, IL‐1β, tumor necrosis factor (TNF)‐α and monocyte chemoattractant protein 1 (MCP‐1) (p<0.05). Furthermore, CA or EA dose dependently down‐regulated tumor necrosis factor‐α and monocyte chemoattractant protein‐1 mRNA expression in kidney (p<0.05). Based on the observed anti‐glycative and anti‐inflammatory effects, the supplement of CA or EA might be helpful for the prevention or attenuation of diabetic kidney diseases.  相似文献   

17.
An α‐l ‐rhamnosidase producing fungal strain has been isolated from decaying lemon fruit. The fungal strain has been identified as Aspergillus flavus. The α‐l ‐rhamnosidase has been purified from the culture filtrate of the fungal strain using ultra filtration and cation exchange chromatography on carboxy methyl (CM) cellulose. The molecular mass of the purified enzyme determined by SDS–PAGE analysis was 41 kDa. The Km values of the enzyme using p‐nitrophenyl‐α‐l ‐rhamnopyranoside and naringin as the substrates were 1.89 and 1.6 mm respectively. The pH and temperature optima of the enzyme were 11.0 and 50 °C respectively. The effects of various chemical species present in grape fruit juice and wine on the activity of the enzyme have been determined.  相似文献   

18.
Summary The heat resistance of a four‐strain mixture of Escherichia coli O157:H7 was tested. The temperature range was 55–62.5 °C and the substrate was beef at pH 4.5 or 5.5, adjusted with either acetic or lactic acid. Inoculated meat, packaged in bags, was completely immersed in a circulating water bath and cooked to an internal temperature of 55, 58, 60, or 62.5 °C in 1 h, and then held for pre‐determined lengths of time. The surviving cell population was enumerated by spiral plating meat samples on tryptic soy agar overlaid with Sorbitol MacConkey agar. Regardless of the acidulant used to modify the pH, the D ‐values at all temperatures were significantly lower (P < 0.05) in ground beef at pH 4.5 as compared with the beef at pH 5.5. At the same pH levels, acetic acid rendered E. coli O157:H7 more sensitive to the lethal effect of heat. The analysis of covariance showed evidence of a significant acidulant and pH interaction on the slopes of the survivor curves at 55 °C. Based on the thermal‐death–time values, contaminated ground beef (pH 5.5/lactic acid) should be heated to an internal temperature of 55 °C for at least 116.3 min and beef (pH 4.5/acetic acid) for 64.8 min to achieve a 4‐log reduction of the pathogen. The heating time at 62.5 °C, to achieve the same level of reduction, was 4.4 and 2.6 min, respectively. Thermal‐death–time values from this study will assist the retail food processors in designing acceptance limits on critical control points that ensure safety of beef originally contaminated with E. coli O157:H7.  相似文献   

19.
With a view to utilise yeast (1→3)‐β‐d ‐glucan as biological response modifiers with better water solubility, carboxymethylation was carried out by a two‐step alkalisation and etherification with monochloroacetic acid. Four technological parameters of carboxymethylation were investigated by orthogonal experiments for obtaining the maximum degree of substitution (DS), apparent viscosity (η) and solubility of carboxymethyl derivatives. In view of the orthogonal analysis, the optimal technological parameters were reaction temperature 50 °C, total reaction time 5 h, 3 mL of 50% sodium hydroxide as the second alkali dosage and 15 mL of 4 m chloroacetic acid. In addition, it was found that ball milling pretreatment for original (1→3)‐β‐d ‐glucan can be an advantage for carboxymethylation. By contrast, DS, η and solubility of carboxymethyl product increased 24%, 6% and 22%, respectively, suggesting the effect of ball milling pretreatment could not be neglected on improvement of DS, η and solubility for carboxymethyl products.  相似文献   

20.
Beans, peas, and lentils are all types of pulses that are extensively used as foods around the world due to their beneficial effects on human health including their low glycaemic index, cholesterol lowering effects, ability to decrease the risk of heart diseases and their protective effects against some cancers. These health benefits are a result of their components such as bioactive proteins, dietary fibre, slowly digested starches, minerals and vitamins, and bioactive compounds. Among these bioactive compounds, γ‐aminobutyric acid (GABA), a non‐proteinogenic amino acid with numerous reported health benefits (e.g. anti‐diabetic and hypotensive effects, depression and anxiety reduction) is of particular interest. GABA is primarily synthesised in plant tissues by the decarboxylation of l ‐glutamic acid in the presence of glutamate decarboxylase (GAD). It is widely reported that during various processes including enzymatic treatment, gaseous treatment (e.g. with carbon dioxide), and fermentation (with lactic acid bacteria), GABA content increases in the plant matrix. The objective of this review paper is to highlight the current state of knowledge on the occurrence of GABA in pulses with special focus on mechanisms by which GABA levels are increased and the analytical extraction and estimation methods for this bioactive phytochemical. © 2017 Society of Chemical Industry  相似文献   

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