共查询到20条相似文献,搜索用时 46 毫秒
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Kameshnee Naidoo Manimaran Ayyachamy Kugen Permaul Suren Singh 《Bioprocess and biosystems engineering》2009,32(5):689-695
Xanthomonas campestris pv phaseoli produced an extracellular endoinulinase (9.24 ± 0.03 U mL−1) in an optimized medium comprising of 3% sucrose and 2.5% tryptone. X. campestris pv. phaseoli was further subjected to ethylmethanesulfonate mutagenesis and the resulting mutant, X. campestris pv. phaseoli KM 24 demonstrated inulinase production of 22.09 ± 0.03 U mL−1 after 18 h, which was 2.4-fold higher than that of the wild type. Inulinase production by this mutant was scaled up using
sucrose as a carbon source in a 5-L fermenter yielding maximum volumetric (21,865 U L−1 h−1) and specific (119,025 U g−1 h−1) productivities of inulinase after 18 h with an inulinase/invertase ratio of 2.6. A maximum FOS production of 11.9 g L−1 h−1 and specific productivity of 72 g g−1 h−1 FOS from inulin were observed in a fermenter, when the mutant was grown on medium containing 3% inulin and 2.5% tryptone.
The detection of mono- and oligosaccharides in inulin hydrolysates by TLC analysis indicated the presence of an endoinulinase.
This mutant has potential for large-scale production of inulinase and fructooligosaccharides. 相似文献
3.
In this study, the cellulase gene celD from Clostridium thermocellum was cloned into expression vectors pET-20b(+) and pHsh. While high expression can be achieved by means of both these expression
systems, only the pHsh expression system gives soluble proteins. By weakening the mRNA secondary structure and replacing the
rare codons for the N-terminal amino acids of the target protein, the expression level of CelD was increased from 4.1 ± 0.3 to 6.4 ± 0.4 U ml−1 in LB medium. Recombinant CelD was purified by heat treatment followed by Ni–NTA affinity. The purified CelD exhibited the
highest activity at pH 5.4 and 60°C, and retained more than 50% activity after incubation at 70°C for 1 h. The cellulase activity
of CelD was significantly enhanced by Ca2+ but inhibited by EDTA. The favorable properties of CelD offer the potential for genetic modification of strains for biomass
degradation. Presently, one of the major bottlenecks for industrial cellulase users is the high cost of enzyme production.
The high level expression of soluble enzymes from the pHsh expression system offers a novel approach for the production of
cellulases to be used in various agro-industrial processes such as chemical, food and textile. 相似文献
4.
The purpose of the present study was to determine the inhibitory activities of two bacteriocins, produced by lactobacilli,
against genital mycoplasmas. In this study, infections produced by genital mycoplasmas were studied; of these, 1.3% were caused
by Mycoplasma hominis, 10.7% by Ureaplasma urealyticum and 5.6% by U. urealyticum + M. hominis. U. urealyticum was isolated from 75 out of 123 patients with genital mycoplasmas, while M. hominis was isolated from 9 patients (7.3%) and both U. urealyticum and M. hominis from 39 patients (31.7%). Bacteriocins, L23 and L60, produced by Lactobacillus fermentum and L. rhamnosus, respectively, appear to be two novel inhibitors of bacterial infection with potential antibacterial activity. Both bacteriocins
proved to be active against 100% of strains tested; MICs of bacteriocin L23 ranged between 320 and 160 UA ml−1 for 78% of the M. hominis strains and between 320 and 80 UA ml−1 for 95% of the U. urealyticum strains. In addition, bacteriocin L60 was still active at 160 UA ml−1 for a high percentage (56%) of M. hominis strains, and at 80 UA ml−1 for 53% of the U. urealyticum strains. Interestingly, these antimicrobial substances produced by lactobacilli showed an inhibitory activity against genital
mycoplasmas even when diluted. Altogether, our study indicates that the bacteriocins, L23 and L60, are good candidates for
the treatment or prevention of genital infections in women. 相似文献
5.
The filamentous fungus Caldariomyces fumago secretes a chloroperoxidase (CPO). To increase its production, we integrated a CPO-expression cassette into the non-transcribed
spacer regions of the rDNA in C. fumago. One strain was obtained that had twice the CPO activity when grown in shake-flask and bioreactor compared to the wild-type.
The highest CPO activity from the bioreactor cultivation was 3,236 U ml−1. This is the highest value reported so far. 相似文献
6.
An artificial fusion protein of Arthrobacter oxydans dextranase and Klebsiella pneumoniae α-amylase was constructed and expressed in Escherichia coli. Most of the expressed protein existed as an insoluble fraction, which was solubilized with urea. The purified fusion enzyme
electrophoretically migrated as a single protein band; M = 137 kDa, and exhibited activities of both dextranase (10.8 U mg−1) and amylase (7.1 U mg−1), which were lower than that of reference dextranase (13.3 U mg−1) and α-amylase (103 U mg−1). The fusion enzyme displayed bifunctional enzyme activity at pH 5–7 at 37°C. These attributes potentially make the fusion
enzyme more convenient for use in sugar processing than a two-enzyme system. 相似文献
7.
Fuhong Xie Yapeng Chao Zhiquan Xue Xiuqing Yang Guoqing Zhang Jiaji Shi Shijun Qian 《Journal of industrial microbiology & biotechnology》2009,36(5):739-746
In industry, fosfomycin is mainly prepared via chemical epoxidation of cis-propenylphosphonic acid (cPPA). The conversion yield of fosfomycin is less than 50% in the whole process and a large quantity
of waste is produced. Biotransformation by microorganisms is an alternative method of preparation. This kind of conversion
is more delicate, environmentally friendly, and the conversion yield of fosfomycin would be higher. In this work, an aerobic
bacterium capable of transforming cPPA to fosfomycin was isolated. The organism, designated as strain S101, was identified
as Bacillus simplex by morphological and physiological characteristics as well as by analysis of the gene encoding the 16S rRNA. Fosfomycin was
assayed by two means, bioassay and gas chromatography (GC). Glycerol was a good carbon source for growth and cPPA conversion
of strain S101. When cPPA was used as the sole carbon source, neither growth nor conversion to fosfomycin occurred. The optimum
cPPA concentration in the conversion medium was 2,000 μg ml−1. After 6 days of incubation, the concentration of fosfomycin reached its maximum level (1,838.2 μg ml−1), with a conversion ratio of 81.3%. Air was indispensable for the growth but not for the conversion to fosfomycin. Furthermore,
vanadium ions were found to be essential for the conversion. High concentrations of cPPA had fewer inhibitory effects on the
growth of strain S101. 相似文献
8.
DC Sabaté MJ Gonzaléz MP Porrini MJ Eguaras MC Audisio JM Marioli 《World journal of microbiology & biotechnology》2012,28(4):1415-1422
The aim of this work was to determine the in vitro effect of the mixture between the lipopeptide surfactin, synthesized by
Bacillus subtilis C4 (strain isolated from honey) and the most active vegetal extract from Achyrocline satureioides, a traditional medicinal plant, on local strains of Paenibacillus larvae, the agent of American Foulbrood in honeybees. Five P. larvae strains isolated in Córdoba, Argentina, were phenotypically characterized. These and 12 other P. larvae strains from different regions of Argentina were analysed. The antimicrobial activities of the essential oil, hexane (HE)
and benzene extracts from A. satureioides were assessed against P. larvae and the HE showed the highest anti-P. larvae activity. A combination of the biosurfactant surfactin, produced by B. subtilis C4, and the HE of A. satureioides revealed a synergistic action on P. larvae. The effective surfactin concentration in the mixture decreased from 32 to 1 μg ml−1 and the HE concentration from 32 to 4 μg ml−1, values similar or equal to minimal inhibitory concentrations observed for oxytetracycline. The fractional inhibitory concentration
index confirmed synergism in 4 strains and partial synergism in one strain. The combination of surfactin synthesized by B. subtilis C4 and the HE from A. satureioides could be a natural alternative to help beekeepers to combat the American foulbrood agent P. larvae. 相似文献
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Vladimir Elisashvili Eva Kachlishvili Nino Tsiklauri Eka Metreveli Tamar Khardziani Spiros N. Agathos 《World journal of microbiology & biotechnology》2009,25(2):331-339
The production of lignocellulolytic enzymes by eleven basidiomycetes species isolated from two ecosystems of Georgia was investigated
for the first time under submerged (SF) and solid-state fermentation (SSF) of lignocellulosic by-products. Notable intergeneric
and intrageneric differences were revealed with regard to the extent of hydrolase and oxidase activity. Several fungi produced
laccase along with hydrolases in parallel with growth during the trophophase, showing that the synthesis of this enzyme is
not connected with secondary metabolism. The lignocellulosic substrate type had the greatest impact on enzyme secretion. Some
of the substrates significantly stimulated lignocellulolytic enzyme synthesis without supplementation of the culture medium
with specific inducers. Exceptionally high carboxymethyl cellulase (CMCase, 122 U ml−1) and xylanase (195 U ml−1) activities were revealed in SF of mandarin peelings by Pseudotremella gibbosa IBB 22 and of residue after ethanol production (REP) by Fomes fomentarius IBB 38, respectively. The SSF of REP by T. pubescens IBB 11 ensured the highest level of laccase activity (24,690 U l−1), whereas the SSF of wheat bran and SF of mandarin peels provided the highest manganese peroxidase activity (570–620 U l−1) of Trichaptum biforme IBB 117. Moreover, the variation of lignocellulosic growth substrate provides an opportunity to obtain enzyme preparations
containing different ratios of individual enzymes. 相似文献
11.
Böer E Breuer FS Weniger M Denter S Piontek M Kunze G 《Applied microbiology and biotechnology》2011,92(1):105-114
Tannase (tannin acyl hydrolase, EC 3.1.1.20) hydrolyses the ester and depside bonds of gallotannins and gallic acid esters
and is an important industrial enzyme. In the present study, transgenic Arxula adeninivorans strains were optimised for tannase production. Various plasmids carrying one or two expression modules for constitutive expression
of tannase were constructed. Transformant strains that overexpress the ATAN1 gene from the strong A. adeninivorans TEF1 promoter produce levels of up to 1,642 U L−1 when grown in glucose medium in shake flasks. The effect of fed-batch fermentation on tannase productivity was then investigated
in detail. Under these conditions, a transgenic strain containing one ATAN1 expression module produced 51,900 U of tannase activity per litre after 142 h of fermentation at a dry cell weight of 162 g L−1. The highest yield obtained from a transgenic strain with two ATAN1 expression modules was 31,300 U after 232 h at a dry cell weight of 104 g L−1. Interestingly, the maximum achieved yield coefficients [Y(P/X)] for the two strains were essentially identical. 相似文献
12.
Syed G. Dastager C. K. Deepa Ashok Pandey 《World journal of microbiology & biotechnology》2011,27(2):259-265
A potential bacterial strain designated as NII-0928 isolated from Western ghat forest soil with multiple plant growth promoting attributes, and it has been identified and characterized. Plant growth promoting
traits were analyzed by determining the P-solubilization efficiency, Indole acetic acid production, HCN, siderophore production
and growth in nitrogen free medium. It was able to solubilize phosphate (76.6 μg ml−1), and produce indole acetic acid (58.9 μg ml−1) at 28 ± 2°C. Qualitative detection of siderophore production and HCN were also observed. At 5°C it was found to express
all the plant growth promotion attributes except HCN production. The ability to colonize roots is a sine qua non condition
for a rhizobacteria to be considered a true plant growth-promoting rhizobacteria (PGPR). 16S rRNA gene sequencing reveals
the identity of the isolate as Serratia nematodiphila with which it shares highest sequence similarity (99.4%). Seed bacterization with black pepper cuttings in greenhouse trials
using Sand: Soil: FYM with three individual experimental sets with their respective control showed clearly the growth promoting
activity. Hence, Serratia nematodiphila NII-0928 is a promising plant growth promoting isolate showing multiple PGPR attributes that can significantly influence
black pepper cuttings. The result of this study provides a strong basis for further development of this strain as a bioinoculants
to attain the desired plant growth promoting activity in black pepper growing fields. 相似文献
13.
Deutch CE 《Antonie van Leeuwenhoek》2011,99(4):781-793
Staphylococcus saprophyticus strains ATCC 15305, ATCC 35552, and ATCC 49907 were found to require l-proline but not l-arginine for growth in a defined culture medium. All three strains could utilize l-ornithine as a proline source and contained l-ornithine aminotransferase and Δ1-pyrroline-5-carboxylate reductase activities; strains ATCC 35552 and ATCC 49907 could use l-arginine as a proline source and had l-arginase activity. The proline requirement also could be met by l-prolinamide, l-proline methyl ester, and the dipeptides l-alanyl-l-proline and l-leucyl-l-proline. The bacteria exhibited l-proline degradative activity as measured by the formation of Δ1-pyrroline-5-carboxylate. The specific activity of proline degradation was not affected by addition of l-proline or NaCl but was highest in strain ATCC 49907 after growth in Mueller–Hinton broth. A membrane fraction from this
strain had l-proline dehydrogenase activity as detected both by reaction of Δ1-pyrroline-5-carboxylate with 2-aminobenzaldehyde (0.79 nmol min−1 mg−1) and by the proline-dependent reduction of p-iodonitrotetrazolium (20.1 nmol min−1 mg−1). A soluble fraction from this strain had Δ1-pyrroline-5-carboxylate dehydrogenase activity (88.8 nmol min−1 mg−1) as determined by the NAD+-dependent oxidation of dl-Δ1-pyrroline-5-carboxylate. Addition of l-proline to several culture media did not increase the growth rate or final yield of bacteria but did stimulate growth during
osmotic stress. When grown with l-ornithine as the proline source, S. saprophyticus was most susceptible to the proline analogues L-azetidine-2-carboylate, 3,4-dehydro-dl-proline, dl-thiazolidine-2-carboxylate, and l-thiazolidine-4-carboxylate. These results indicate that proline uptake and metabolism may be a potential target of antimicrobial
therapy for this organism. 相似文献
14.
Bacterial biofilms are associated with chronic infections due to their resistance to antimicrobial agents. Staphylococcus
aureus is a versatile human pathogen and can form biofilms on human tissues and diverse medical devices. To identify novel biofilm
inhibitors of S. aureus, the supernatants from a library of 458 Actinomycetes strains were screened. The culture supernatants (1% v/v) of more than 10 Actinomycetes strains inhibited S. aureus biofilm formation by more than 80% without affecting the growth. The culture supernatants of these biofilm-reducing Actinomycetes strains contained a protease (equivalent to 0.1 μg proteinase K ml−1), which both inhibited S. aureus biofilm formation and detached pre-existing S. aureus biofilms. This study suggests that protease treatment could be a feasible tool to reduce and eradicate S. aureus biofilms. 相似文献
15.
Ping Su Anders Henriksson Christina Nilsson Hazel Mitchell 《World journal of microbiology & biotechnology》2008,24(9):1837-1842
The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three
probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against
Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both
Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by
24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately.
These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections
caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important
adjuncts to, or alternatives to, conventional antibiotic therapy. 相似文献
16.
Yanfeng Tuo Lanwei Zhang Xue Han Ming Du Yingchun Zhang Huaxi Yi Weiqin Zhang Yuehua Jiao 《World journal of microbiology & biotechnology》2011,27(3):505-511
The objective of this study was to evaluate the in vitro immunomodulating capacity of Lactobacillus
coryniformis subsp torquens T3L (L.
coryniformis T3L) isolated from traditional fermented yak’s milk in Tibet, China, and Lactobacillus paracasei supsp. paracasei M5L (L. paracasei M5L)isolated from kumiss in Sinkiang, China was used as control. The effects of live bacteria, cell wall and genomic DNA
of the two Lactobacillus strains on human peripheral blood mononuclear cells (PBMCs) proliferation, production of interleukin-12 (IL-12 p70), interferon
gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), and natural killer (NK) cell activity were assessed. The live bacteria,
cell wall and genomic DNA of the two lactobacilli exerted proliferative effects on PBMCs. Live bacteria at 1 × 106 c.f.u. ml−1, cell wall at 20 μg protein ml−1 and DNA at 50 μg DNA ml−1 of the strainS induced the secretion of IL-12 (p70), IFN-γ and TNF-α by PBMCs. NK cell activities increased after cultivation
of PBMCs with live bacteria, cell wall and DNA of the strains. Overall, these results demonstrate that the live bacteria,
cell wall and genomic DNA of the two Lactobacillus strains exhibit immunomodulating activity. 相似文献
17.
F. D. Espasandin M. M. Collavino C. V. Luna R. C. Paz J. R. Tarragó O. A. Ruiz L. A. Mroginski P. A. Sansberro 《Plant Cell, Tissue and Organ Culture》2010,102(2):181-189
A protocol for the production of transgenic plants was developed for Lotus tenuis via Agrobacterium-mediated transformation of leaf segments. The explants were co-cultivated (for 3 days) with an A. tumefaciens strain harbouring either the binary vector pBi RD29A:oat arginine decarboxylase (ADC) or pBi RD29A:glucuronidase (GUS), which
carries the neomycin phosphotransferase II (nptII) gene in the T-DNA region. Following co-cultivation, the explants were cultured in Murashige and Skoog medium supplemented
with naphthalenacetic acid (NAA) and benzyladenine (BA) and containing kanamycin (30 μg ml−1) and cefotaxime (400 μg ml−1) for 45 days. The explants were subcultured several times (at 2-week intervals) to maintain the selection pressure during
the entire period. About 40% of the explants inoculated with the pBiRD29:ADC strain produced eight to ten adventitious shoots
per responsive explant through a direct system of regeneration, whereas 69% of the explants inoculated with the pBi RD29A:GUS
strain produced 13–15 adventitious shoots per responsive explant. The selected transgenic lines were identified by PCR and
Southern blot analysis. Three ADC transgenic lines were obtained from 30 infected explants, whereas 29 GUS transgenic lines
were obtained from 160 explants, corresponding to a transformation efficiency of 10 and 18.1%, respectively. More than 90%
of the in vitro plantlets were successfully transferred to the soil. The increase in the activity of arginine decarboxylase
from stressed ADC- Lt19 lines was accompanied by a significant rise in the putrescine level. The GUS transgenic line driven by the RD29A promoter
showed strong signals of osmotic stress in the leaves and stem tissues. All of the transgenic plants obtained exhibited the
same phenotype as the untransformed controls under non-stress conditions, and the stability of the gene introduced into the
cloned materials was established. 相似文献
18.
Gao Z Li Z Zhang Y Huang H Li M Zhou L Tang Y Yao B Zhang W 《Biotechnology letters》2012,34(3):507-514
The glucose oxidase (GOD) gene from Penicillium notatum was expressed in Pichia pastoris. The 1,815 bp gene, god-w, encodes 604 amino acids. Recombinant GOD-w had optimal activity at 35–40°C and pH 6.2 and was stable, from pH 3 to 7 maintaining >75%
maximum activity after incubation at 50°C for 1 h. GOD-w worked as well as commercial GODs to improve bread making. To achieve
high-level expression of recombinant GOD in P. pastoris, 272 nucleotides involving 228 residues were mutated, consistent with the codon bias of P. pastoris. The optimized recombinant GOD-m yielded 615 U ml−1 (2.5 g protein l−1) in a 3 l fermentor—410% higher than GOD-w (148 U ml−1), and thus is a low-cost alternative for the bread baking industry. 相似文献
19.
SM Cedrola AC de Melo AM Mazotto U Lins RB Zingali AS Rosado RS Peixoto AB Vermelho 《World journal of microbiology & biotechnology》2012,28(3):1259-1269
The aim of this study is to investigate the culture conditions of chicken feather degradation and keratinolytic enzyme production
by the recently isolated Bacillus subtilis SLC and to evaluate the potential of the SLC strain to recycle feather waste discarded by the poultry industry. The SLC strain
was isolated from the agroindustrial waste of a poultry farm in Brazil and was confirmed to belong to Bacillus subtilis by rDNA gene analysis. There was high keratinase production when the medium was at pH 8 (280 U ml−1). Activity was higher using the inoculum propagated for 72 h on 1% whole feathers supplemented with 0.1% yeast extract. In
the enzymatic extract, the keratinases were active in the pH range from 2.0 to 12.0 with a maximum activity at pH 10.0 and
temperature 60°C. For gelatinase the best pH was 5.0 and the best temperature was 37°C. All keratinases are serine peptidases.
The crude enzymatic extract degraded keratin, gelatin, casein, and hemoglobin. Scanning electron microscopy showed Bacillus cells adhered onto feather surfaces after 98 h of culture and degraded feather filaments were observed. MALDI-TOF mass spectrometric
analysis showed multiple peaks from 522 to 892 m/z indicating feather degradation. The presence of sulfide was detected on
extracellular medium probably participating in the breakdown of sulfide bridges of the feather keratin. External addition
of sulfide increased feather degradation. 相似文献
20.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献