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1.
Dams-Kozlowska H Mercaldi MP Panilaitis BJ Kaplan DL 《Applied microbiology and biotechnology》2008,81(2):201-210
Since its discovery in the late 1970s, emulsan has been the subject of significant interest for fundamental biosynthesis and
structure–function relationships as well as for its potential industrial applications. These studies initially examined the
emulsification properties of the compound, while more recent efforts have focused on potential biomedical applications. As
a result of this change of focus, it became necessary to more completely characterize the structure of the emulsan molecule
and to develop a more reproducible purification process. We review previous studies with emulsan and explain how prior notions
were recently shown to be incorrect through the development of a new purification process. More recent genetic modification
of the relevant operon is also reviewed. Finally, the potential applications for the new purified polymer will be discussed. 相似文献
2.
The effects of cultivation medium compositions including soybean meal, peptone, soybean oil and cornstarch for actinomycin X2 production by Streptomyces spp JAU4234 were accessed by using response surface methodology. The 2(4) full factorial designs and the paths of steepest ascent were effective in searching for the major factors of actinomycin X2 production. In this study, cornstarch and soybean oil showed negative effect on actinomycin X2 production based on the first-order regression coefficients derived from MINITAB software. Subsequently, a central composite design for optimization was further investigated. Preliminary studies showed that soybean meal and peptone were believed to be the major factors for actinomycin X2 production. Estimated optimum compositions for the production of actionmycin X2 were as follows (g/l): soybean meal 21.65 and peptone 9.41, and result in a maximum actionmycin X2 production of 617.4 mg/l. This value was closed to the 612 mg/l actionmycin X2 production from actual experimental observations. The yield of actionmycin X2 was increased by 36.9% by culturing the strain Streptomyces spp JAU4234 in the nutritionally optimized fermentation medium. 相似文献
3.
Lovastatin, an inhibitor of HMG-CoA reductase, was produced by submerged fermentation using Monascus purpureus MTCC 369. Five nutritional parameters screened using Plackett–Burman experimental design were optimized by Box–Behnken factorial
design of response surface methodology for lovastatin production in shake flask cultures. Maximum lovastatin production of
351 mg/l were predicted in medium containing 29.59 g/l dextrose, 3.86 g/l NH4Cl, 1.73 g/l KH2PO4, 0.86 g/l MgSO4·7H2O, and 0.19 g/l MnSO4·H2O using response surface plots and point prediction tool of DESIGN EXPERT 7.0 (Statease, USA) software. 相似文献
4.
Iturin A, a lipopeptide antibiotic produced by Bacillus subtilis RB14-CS, suppresses the growth of various plant pathogens. Here, enhancement of iturin A production in solid-state fermentation
(SSF) on okara, a soybean curd residue produced during tofu manufacturing, was accomplished using statistical experimental
design. Primary experiments showed that the concentrations of carbon and nitrogen sources were the main factors capable of
enhancing iturin A production, whereas initial pH, initial water content, temperature, relative humidity, and volume of inoculum
were only minor factors. Glucose and soybean meal were the most effective among tested carbon and nitrogen sources, respectively.
Based on these preliminary findings, response surface methodology was applied to predict the optimum amounts of the carbon
and nitrogen sources in the medium. The maximum iturin A concentration was 5,591 μg/g initial wet okara under optimized condition.
Subsequent experiments confirmed that iturin A production was significantly improved under the predicted optimal medium conditions.
The SSF product generated under the optimized conditions exhibited significantly higher suppressive effect on the damping-off
of tomato caused by Rhizoctonia solani K-1 compared with the product generated under the non-optimized conditions. 相似文献
5.
Traditional mycelium aging technology was improved to enhance arachidonic acid (ARA) production by Mortierella alpina ME-1. Filtration step was skipped and additional carbon and nitrogen sources were fed during aging. The levels of the significant
factors (time, temperature, ethanol, and KNO3) affecting ARA production during improved aging process were also optimized by applying response surface methodology (RSM),
and the maximum ARA yield of 19.02 g/l was achieved in a 5 l fermentor at 5.6 days, temperature 13.7 °C, ethanol 42.44 g/l,
and KNO3 2.62 g/l. This yield was 1.55 times higher than that of traditional aging technology. The improved mycelium aging technology
is considered to be a useful strategy for enhancing ARA production. 相似文献
6.
Culture medium for keratinase production from hair substrate by a new Bacillus subtilis strain, KD-N2, was optimized. Effects of culture conditions on keratinase production were tested, and optimal results were
obtained with 10% inocula (v/v), 16 g/L hair substrate, an initial pH value of 6.5 and a culture volume of 20 mL. Several
carbon sources (sucrose, cornflour) and nitrogen sources (yeast extract, tryptone and peptone) had positive effects on keratinase
production, with sucrose giving optimal results. To improve keratinase yield, statistically based experimental designs were
applied to optimize the culture medium. Fractional factorial design (FFD) experiments showed that MgSO4 and K2HPO4 were the most significant factors affecting keratinase production. Further central composite design (CCD) experiments indicated
that the optimal MgSO4 and K2HPO4 concentrations were 0.91 and 2.38 g/L, respectively. Using an optimized fermentation medium (g/L: NaCl 1.0, CaCl2 0.05, KH2PO4 0.7, sucrose 3, MgSO4 0.91, K2HPO4 2.38), keratinase activity increased to 125 U/mL, an approximate 1.7-fold increase over the previous activity (75 U/mL).
Human hair was degraded during the submerged cultivation. 相似文献
7.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
8.
The nutritional requirements for phenazine-1-carboxylic acid (PCA) production using Pseudomonas sp. M18G, a gacA chromosomal-inactivated mutant of the strain M18, with a high PCA yield, were optimized statistically in shake flask experiments.
Based on a single-factor experiment design, we implemented the two-level Plackett–Burman (PB) design with 11 variables to
screen medium components that significantly influence PCA production. Soybean meal, glucose, soy peptone, and ethanol were
identified as the most important significant factors (P < 0.05). Response surface methodology based on the Center Composite Design (CCD) was applied to determine these factors’
optimal levels and their mutual interactions between components for PCA production. The predicted results showed that 1.89 g
l−1 of PCA production was obtained after a 60-h fermentation period, with optimal concentrations of soybean meal powder (33.4 g
l−1), glucose (12.7 g l−1), soy peptone (10.9 g l−1), and ethanol (13.8 ml l−1) in the flask fermentations. The validity of the model developed was verified, and the optimum medium led to a maximum PCA
concentration of 2.0 g l−1, a nearly threefold increase compared to that in the basal medium. Furthermore, the experiment was scaled up in the 10 l
fermentor and 2 g l−1 PCA productions were achieved in 48 h based on optimization mediums which further verified the practicability of this optimum
strategy. 相似文献
9.
Response surface methodology (RSM) was applied to optimize the critical medium ingredients of Agaricus blazei. A three-level Box–Behnken factorial design was employed to determine the maximum biomass and extracellular polysaccharide
(EPS) yields at optimum levels for glucose, yeast extract (YE), and peptone. A mathematical model was then developed to show
the effect of each medium composition and its interactions on the production of mycelial biomass and EPS. The model predicted
the maximum biomass yield of 10.86 g/l that appeared at glucose, YE, peptone of 26.3, 6.84, and 6.62 g/l, respectively, while
a maximum EPS yield of 348.4 mg/l appeared at glucose, YE, peptone of 28.4, 4.96, 5.60 g/l, respectively. These predicted
values were also verified by validation experiments. The excellent correlation between predicted and measured values of each
model justifies the validity of both the response models. The results of bioreactor fermentation also show that the optimized
culture medium enhanced both biomass (13.91 ± 0.71 g/l) and EPS (363 ± 4.1 mg/l) production by Agaricus blazei in a large-scale fermentation process. 相似文献
10.
Fermentation conditions were statistically optimized for producing extracellular xylanase by Aspergillus niger SL-05 using apple pomace and cotton seed meal. The primary study shows that culture medium with a 1:1 ratio of apple pomace and cotton seed meal (carbon and nitrogen sources) yielded maximal xylanase activity. Three significant factors influencing xylanase production were identified as urea, KH(2)PO(4), and initial moisture content using Plackett-Burman design study. The effects of these three factors were further investigated using a design of rotation-regression-orthogonal combination. The optimized conditions by response surface analysis were 2.5% Urea, 0.09% KH(2)PO(4), and 62% initial moisture content. The analysis of variance indicated that the established model was significant (P < 0.05), "while" or "and" the lack of fit was not significant. Under the optimized conditions, the model predicted 4,998 IU/g dry content, whereas validation experiments produced an enzymatic activity of xylanase at 5,662 IU/g dry content after 60 h fermentation. This study innovatively developed a fermentation medium and process to utilize inexpensive agro-industrial wastes to produce a high yield of xylanase. 相似文献
11.
Ning Guo Fang Gong Zhenming Chi Jun Sheng Jing Li 《Journal of industrial microbiology & biotechnology》2009,36(4):499-507
In order to isolate inulinase overproducers of the marine yeast Pichia guilliermondii, strain 1, cells were mutated by using UV light and LiCl2. One mutant (M-30) with enhanced inulinase production was obtained. Response surface methodology (RSM) was used to optimize
the medium compositions and cultivation conditions for inulinase production by the mutant in solid-state fermentation. The
initial moisture, inoculum, the amount ratio of wheat bran to rice bran, temperature, pH for the maximum inulinase production
by the mutant M-30 were found to be 60.5%, 2.5%, 0.42, 30°C and 6.50, respectively. Under the optimized conditions, 455.9 U/grams
of dry substrate (gds) of inulinase activity was reached in the solid state fermentation culture of the mutant M-30 whereas
the predicted maximum inulinase activity of 459.2 U/gds was derived from RSM regression. Under the same conditions, its parent
strain only produced 291.0 U/gds of inulinase activity. This is the highest inulinase activity produced by the yeast strains
reported so far. 相似文献
12.
Notocactus scopa cv. Soonjung was subjected to in planta Agrobacterium tumefaciens-mediated transformation with vacuum infiltration, pin-pricking, and a combination of the two methods. The pin-pricking combined with vacuum infiltration (20-30 cmHg for 15 min) resulted in a transformation efficiency of 67-100%, and the expression of the uidA and nptII genes was detected in transformed cactus. The established in planta transformation technique generated a transgenic cactus with higher transformation efficiency, shortened selection process, and stable gene expression via asexual reproduction. All of the results showed that the in planta transformation method utilized in the current study provided an efficient and time-saving procedure for the delivery of genes into the cactus genome, and that this technique can be applied to other asexually reproducing succulent plant species. 相似文献
13.
We isolated several mutants of Arabidopsis thaliana (L.) Heynh. that accumulated less anthocyanin in the plant tissues, but had seeds with a brown color similar to the wild-type.
These mutants were allelic with the anthocyaninless1 (anl1) mutant that has been mapped at 15.0 cM of chromosome 5. We performed fine mapping of the anl1 locus and determined that ANL1 is located between the nga106 marker and a marker corresponding to the MKP11 clone. About 70 genes are located between these
two markers, including three UDP-glucose:flavonoid-3-O-glucosyltransferase-like genes and a glutathione transferase gene (TT19). A mutant of one of the glucosyltransferase genes (At5g17050) was unable to complement the anl1 phenotype, showing that the ANL1 gene encodes UDP-glucose:flavonoid-3-O-glucosyltransferase. ANL1 was expressed in all tissues examined, including rosette leaves, stems, flower buds and roots. ANL1 was not regulated by TTG1. 相似文献
14.
Phylogenetic relations within the genus Gordonia were analyzed using partial gyrB and secA1 gene sequences of 23 type species in comparison with those of 16S rRNA gene. The gyrB and secA1 phylogenies showed agreement with that constructed using 16S rRNA gene sequences. The degrees of divergence of the gyrB and secA1 genes were approximately 3.4 and 1.7 times greater, respectively, than that of 16S rRNA gene. The gyrB gene showed more discriminatory power than either the secA1 or 16S rRNA gene, facilitating clear differentiation of any two Gordonia species using gyrB gene analysis. Our data indicate that gyrB and secA1 gene sequences are useful as markers for phylogenetic study and identification at the species level of the genus Gordonia. 相似文献
15.
José Miguel Müller Ranulfo Monte Alegre 《World journal of microbiology & biotechnology》2007,23(5):691-695
In this study alginate production by Pseudomonas mendocina in a laboratory-scale fermenter was investigated. In the experiments the effect of temperature (25–31°C) and agitation (500–620 rev min−1) at a constant air flow of 10 v/v/h were evaluated in relation to the rate of glucose bioconversion to alginate using response
surface methodology (RSM). The fermenter configuration was also adapted to a system with a screw mixer and draft tube, due
to the change in rheological characteristics of the fermentation broth. The adjusted model indicates a temperature of 29.1°C
and agitation of 553 rev min−1 for optimum alginate synthesis. In this fermentation system a Y
p/s
of 44.8% was achieved. The alginate synthesized by P. mendocina showed a partially acetylated pattern as previously reported for alginates obtained from other Pseudomonas spp and Azotobacter vinelandii. 相似文献
16.
Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification
generates synthesis gas consisting primarily of CO, CO2, H2, N2, with smaller amounts of CH4, NOx, O2, C2 compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents.
However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to
enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation.
Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels
of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing
cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios. 相似文献
17.
Young Tae Kim Kang Seon Lee Moon Jung Kim Seung Bum Kim 《Journal of microbiology (Seoul, Korea)》2009,47(1):33-39
The effects of Chinese cabbage (Brassica rapa subsp. pekinensis) carrying cry1AC derived from Bacillus thuringiensis (Bt) on leaf bacterial community were examined by analyzing the horizontal transfer of trans-gene fragments from plants to
bacteria. The effect of plant pathogenic bacteria on the gene transfer was also examined using Pseudomonas syringae pathovar. maculicola. The frequency of hygromycin-resistant bacteria did not alter in Bt leaves, though slight increase was observed in Pseudomonas-infected Bt leaves with no statistical significance. The analysis of bacterial community profiles using the denaturing gradient
gel electrophoresis (DGGE) fingerprinting indicated that there were slight differences between Bt and control Chinese cabbage,
and also that infected tissues were dominated by P. syringae pv. maculicola. However, the cultured bacterial pools were not found to contain any transgene fragments. Thus, no direct evidence of immediate
gene transfer from plant to bacteria or acquisition of hygromycin resistance could be observed. Still, long-term monitoring
on the possibility of gene transfer is necessary to correctly assess the environmental effects of the Bt crop on bacteria. 相似文献
18.
A new deletion allele of the APETALA1 (AP1) gene encoding a type II MADS-box protein with the key role in the initiation of flowering and development of perianth organs has been identified in A. thaliana. The deletion of seven amino acids in the conserved region of the K domain in the ap1-20 mutant considerably delayed flowering and led to a less pronounced abnormality in the corolla development compared to the weak ap1-3 and intermediate ap1-6 alleles. At the same time, a considerable stamen reduction has been revealed in ap1-20 as distinct from ap1-3 and ap1-6 alleles. These data indicate that the K domain of AP1 can be crucial for the initiation of flowering and expression regulation of B-class genes controlling stamen development. 相似文献
19.
Stefanie Kimbacher Ingrid Gerstl Branko Velimirov Sylvia Hagemann 《Molecular genetics and genomics : MGG》2009,282(2):165-172
P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding
region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献