共查询到20条相似文献,搜索用时 15 毫秒
1.
Malaisse WJ Olivares E Belcourt A Nilsson K 《Applied microbiology and biotechnology》1999,52(5):652-653
Dispersed pancreatic islet cells from rats were cultured overnight in the presence of macroporous gelatin microcarriers.
The cells attached to the microcarriers were then incubated for 90 min in the absence or presence of 15.0 mM d-glucose and/or 1.25 mM theophylline. The release of insulin during incubation was about three times higher in the simultaneous
presence of these two secretagogues than in their absence. This procedure could thus be used for the immobilization of pancreatic
islet cells with preserved secretory potential.
Received: 9 April 1999 / Received revision: 12 July 1999 / Accepted: 13 July 1999 相似文献
2.
A heat shock following electroporation induces highly efficient transformation of Corynebacterium glutamicum with xenogeneic plasmid DNA 总被引:10,自引:0,他引:10
An improved method for the electrotransformation of wild-type Corynebacterium glutamicum (ATCC 13032) is described. The two crucial alterations to previously developed methods are: cultivation of cells used for
electrotransformation at 18 °C instead of 30 °C, and application of a heat shock immediately following electrotransformation.
Cells cultivated at sub optimal temperature have a 100-fold improved transformation efficiency (108 cfu μg−1) for syngeneic DNA (DNA isolated from the same species). A heat shock applied to these cells following electroporation improved
the transformation efficiency for xenogeneic DNA (DNA isolated from a different species). In combination, low cultivation
temperature and heat shock act synergistically and increased the transformation efficiency by four orders of magnitude to
2.5 × 106 cfu μg−1 xenogeneic DNA. The method was used to generate gene disruptions in C. glutamicum.
Received: 26 March 1999 / Received revision: 9 June 1999 / Accepted: 11 June 1999 相似文献
3.
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens for the production of succinic acid from whey 总被引:3,自引:0,他引:3
Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l−1 yeast extract and 2.5 g l−1 polypeptone per 10 g l−1 whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l−1 nontreated whey and 7 g l−1 glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95%
and 0.46 g (l h)−1, respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (l h)−1 for 20 g l−1 whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (l h)−1], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey.
Received: 23 July 1999 / Received revision: 17 November 1999 / Accepted: 24 December 1999 相似文献
4.
The agaric basidiomycete Clitocybula dusenii was used for the production of the extracellular ligninolytic enzyme, manganese (Mn) peroxidase. An immobilization technique
is described using cellulose and polypropylene as carrier for the fungal mycelium. High amounts of Mn peroxidase were obtained
with agitated cultures of immobilized fungus (up to 3,000 U l−1) while the biomass was recovered and used for further production cycles. Purification of Mn peroxidase revealed the existence
of two forms: MnP1 (molecular mass 43 kDa, pI 4.5) and MnP2 (42 kDa, pI 3.8).
Received: 30 July 1999 / Received revision: 1 December 1999 / Accepted: 3 December 1999 相似文献
5.
Rajaguru P Kalaiselvi K Palanivel M Subburam V 《Applied microbiology and biotechnology》2000,54(2):268-273
A sequential anaerobic–aerobic treatment process based on mixed culture of bacteria isolated from textile dye effluent-contaminated
soil was used to degrade sulfonated azo dyes Orange G (OG), Amido black 10B (AB), Direct red 4BS (DR) and Congo red (CR).
Under anaerobic conditions in a fixed-bed column using glucose as co-substrate, the azo dyes were reduced and amines were
released by the bacterial biomass. The amines were completely mineralized in a subsequent aerobic treatment using the same
isolates. The maximum degradation rate observed in the treatment system for OG was 60.9 mg/l per day (16.99 mg/g glucose utilized),
for AB 571.3 mg/l per day (14.46 mg/g glucose utilized), for DR 112.5 mg/l per day (32.02 mg/g glucose utilized) and for CR
134.9 mg/l per day (38.9 mg/g glucose utilized).
Received: 6 August 1999 / Received revision: 20 December 1999 / Accepted: 24 December 1999 相似文献
6.
Pseudomonas mendocina MCM B-402 was found to utilize a triphenylmethane dye, methyl violet as the sole source of carbon when incorporated in synthetic
medium. Almost complete decolorization of methyl violet by P. mendocina was observed within 48 h of incubation at ambient temperature (28 ± 2 °C) under aerated culture conditions, when the bacteria
were inoculated into Davis Mingioli's synthetic medium at a concentration of 100 mg/l medium. Methyl violet was mineralized
to CO2 through three unknown intermediate metabolites and phenol. The decolorization of the dye involved demethylation.
Received: 27 November 1998 / Received revision: 2 March 1999 / Accepted: 5 March 1999 相似文献
7.
Parshikov IA Freeman JP Williams AJ Moody JD Sutherland JB 《Applied microbiology and biotechnology》1999,52(4):553-557
Cultures of the fungi Aspergillus niger, Cunninghamella verticillata, and Penicillium simplicissimum, grown in a sucrose/peptone medium, transformed N-acetylphenothiazine to N-acetylphenothiazine sulfoxide (from 13% to 28% of the total) and phenothiazine sulfoxide (from 5% to 27%). Phenothiazin-3-one
(4%) and phenothiazine N-glucoside (4%) were also produced by C. verticillata. The probable intermediate, phenothiazine, was detected only in cultures of P. simplicissimum (6%).
Received: 15 January 1999 / Received revision: 7 May 1999 / Accepted: 21 May 1999 相似文献
8.
J. Oddou C. Stentelaire L. Lesage-Meessen M. Asther B. Colonna Ceccaldi 《Applied microbiology and biotechnology》1999,53(1):1-6
High-density cultures of Pycnoporus cinnabarinus were tested with a view to optimisation of ferulic acid bioconversion into vanillin. The dry weight was increased fourfold
by using glucose, fructose or a mixture of glucose and phospholipids as carbon source instead of maltose, the carbon source
previously used. 5 mmol l−1 vanillin, i.e. 760 mg l−1, was produced over 15 days with glucose-phospholipid medium. In contrast, formation of vanillin was lower using glucose or
fructose compared to the maltose control. A bioreactor (2 l) with a glucose-phospholipid medium gave a molar yield of vanillin
of 61% (4 mmol l−1). An alternative strategy was to grow the fungus on a glucose or fructose medium for 3 days, then switch to maltose during
the bioconversion phase: this method allowed 3.3 mmol l−1 vanillin to be obtained in 10 days. Many by-products such as methoxyhydroquinone and vanillyl alcohol were also produced.
Received: 19 February 1999 / Received revision: 4 June 1999 / Accepted: 4 June 1999 相似文献
9.
Production of (R)-3-pentyn-2-ol through stereoinversion of racemic 3-pentyn-2-ol by Nocardia fusca AKU 2123 总被引:1,自引:0,他引:1
Wet cells of Nocardia fusca AKU 2123 are good catalysts for the production of (R)-3-pentyn-2-ol (PYOH) from (RS)-PYOH through a stereoinversion reaction. Under optimal conditions (350 mM potassium phosphate buffer, pH 8.0, 30% (w/v)
wet cells, 0.12% NADPH, 10% glucose, and 30 U/ml glucose dehydrogenase) (R)-PYOH of high optical purity (98.7% e.e.) was produced from 2% (v/v) (RS)-PYOH with a yield of 70.4% by 140 h incubation.
Received: 22 January 1999 / Received revision: 23 April 1999 / Accepted: 1 May 1999 相似文献
10.
C. Suresh A. K. Dubey S. Srikanta S. Umesh Kumar N. G. Karanth 《Applied microbiology and biotechnology》1999,51(5):673-675
A UV-induced mutant strain of Aspergillus niger (CFTRI-1105-U9) overproduced a starch-hydrolysing enzyme with properties characteristically different from the known amylases
of the fungus. The purified enzyme of 4.0 pI had an apparent molecular mass of 125 kDa and it dextrinised starch and then
saccharified the dextrins. Patterns of the enzyme activity on starch, resulting in glucose at 60 °C and glucose, maltose and
maltodextrins at 70 °C as primary products, suggested significant applications for the enzyme in starch-processing industries.
Received: 29 October 1998 / Received revision: 11 January 1999 / Accepted: 19 January 1999 相似文献
11.
A continuously growing callus was obtained from immature endosperm of Morus alba L Cv S-36 cultured on Murashige and Skoog medium containing 5 μm 2,4-dichlorophenoxyacetic acid. Shoot buds were produced
when the callus was subcultured on a medium containing a cytokinin or a cytokinin and 1-naphthaleneacetic acid (NAA). The
maximum number of shoots was formed on the medium containing thidiazuron (1 μM), or benzylaminopurine (5 μM) and NAA (1 μM).
Shoots were multiplied by forced axillary branching and rooted in vitro. Endosperm-derived plants were established in soil.
Each of the ten plants examined cytologically was triploid (3 n=42).
Received:17 February 1999 / Revision received: 4 May 1999 / Accepted: 19 May 1999 相似文献
12.
Simultaneous bioconversion of glucose and xylose to ethanol by Saccharomyces cerevisiae in the presence of xylose isomerase 总被引:3,自引:0,他引:3
Simultaneous isomerisation and fermentation (SIF) of xylose and simultaneous isomerisation and cofermentation (SICF) of a
glucose/xylose mixture was carried out by Saccharomyces cerevisiae in the presence of xylose isomerase. The SIF of 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 7.5 g l−1 and 0.36 g (g xylose consumed)−1. These parameters improved to 13.4 g l−1 and 0.40 respectively, when borate was added to the medium. The SICF of a mixture of 50 g l−1 glucose and 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 29.8 g l−1 and 0.42 respectively, in the presence of borate. Temperature modulation from 30 °C to 35 °C during fermentation further
enhanced the above parameters to 39 g l−1 and 0.45 respectively. The approach was extended to the bioconversion of sugars present in a real lignocellulose hydrolysate
(peanut-shell hydrolysate) to ethanol, with a fairly good yield.
Received: 14 May 1999 / Received revision: 27 September 1999 / Accepted: 2 October 1999 相似文献
13.
Resting cells of a locally isolated strain of Aspergillus niger caused the bioconversion of alpha pinene to verbenone. The formation of verbenone was raised from trace amounts (under screening
conditions) to 3.28 mg/100 ml (equivalent to a molar yield of 16.5% conversion of the substrate) by amending the cultivation
medium for the fungus. The optimal conditions were: 6 g/100 ml for the glucose concentration, a pH of 7.0, an alpha pinene
concentration of 20 mg/100 ml, and a 6-h incubation period for the reaction.
Received: 9 August 1999 / Received revision: 24 September 1999 / Accepted: 24 September 1999 相似文献
14.
Laccase, purified from Coriolus versicolor, removed pentachlorophenol (PCP) from solution at pH 5, depending on initial PCP concentration and amount of laccase. With
100 units of laccase, 100% of 25 μg ml−1 PCP and 60% of 200 μg ml−1 PCP were removed respectively over 72 h. No free chloride was released in the reaction. In reaction with 100 μg PCP, products
were primarily polymers (about 80,000 MW) with only 2–3 pg of o- and p-chloranils formed. Polymers were stable to acid hydrolysis and no release of PCP, or other low-molecular-weight products,
was detected over several weeks. Laccase has a potential use in the biotreatment of aqueous effluents containing PCP, with
polymerised products being removed from solution due to their high molecular weight.
Received: 7 June 1999 / Received revision: 18 August 1999 / Accepted: 2 September 1999 相似文献
15.
Pollutant degradation in biotrickling filters for waste air treatment is generally thought to occur only in the biofilm.
In two experiments with toluene degrading biotrickling filters, we show that suspended microorganisms in the recycle liquid
may substantially contribute to the overall pollutant removal. Two days after reactor start up, the overall toluene elimination
capacity reached a maximum of 125 g m−3 h−1, which was twice that found during prolonged operation. High biodegradation activity in the recycle liquid fully accounted
for this short-term peak of pollutant elimination. During steady-state operation, the toluene degradation in the recycle liquid
was 21% of the overall elimination capacity, although the amount of suspended biomass was only 1% of the amount of immobilized
biomass. The results suggest that biotrickling filter performance may be improved by selecting operating conditions allowing
for the development of an actively growing suspended culture.
Received: 16 June 1999 / Received revision: 17 November 1999 / Accepted: 15 December 1999 相似文献
16.
The esterification reaction between stearic acid and lactic acid using Rhizomucor miehei lipase and porcine pancreas lipase was optimized for maximum esterification using response surface methodology. The formation
of the ester was found to depend on three parameters namely enzyme/substrate ratio, lactic acid (stearic acid) concentration
and incubation period. The maximum esterification predicted by theoretical equations for both lipases matched well with the
observed experimental values. In the case of R. miehei lipase, stearoyl lactic acid ester formation was found to increase with incubation period and lactic acid (stearic acid)
concentrations with maximum esterification of 26.9% at an enzyme/substrate (E/S) ratio of 125 g mol−1. In the case of porcine pancreas lipase, esterification showed a steady increase with increase in incubation period and lactic
acid (stearic acid) concentration independent of the E/S ratios employed. In the case of PPL, a maximum esterification of
18.9% was observed at an E/S ratio of 25 g mol−1 at a lactic acid (stearic acid) concentration of 0.09 M after an incubation period of 72 h.
Received: 12 February 1999 / Received revision: 31 May 1999 / Accepted: 4 June 1999 相似文献
17.
We investigate the effect of spatial aggregation in the infection dynamics of nematode parasites in ruminants. We show that
a high degree of spatial aggregation is likely to lead to a dramatically enhanced rate of invasion by drug-resistant strains.
Received: 13 December 1999 / Revised version: 3 April 2000 / Published online: 4 October 2000 相似文献
18.
Nutrient requirements of lactococci in defined growth media 总被引:12,自引:0,他引:12
Many attempts have been made for the last six decades to design defined media for species of the lactococcus group. The general
outcome of the studies suggests that this group is heterogeneous with respect to specific requirements for nutrients. Lactococcal
species are limited in various metabolic pathways. Early attempts to trace the required nutrients were not always successful
because of the poor quality of analysis and the presence of impurities in the medium components.
Received: 15 January 1999 / Received revision: 6 April 1999 / Accepted: 9 April 1999 相似文献
19.
Succinoglycan was produced by cultivating Agrobacterium tumefaciens on various solid substrates, including agar medium, spent malt grains, ivory nut shavings, and grated carrots, impregnated
with a nutrient solution. Fermentations were performed on a laboratory scale, both under static conditions and with agitation,
using bottles and a prototype horizontal bioreactor. Several fermentation parameters were examined and optimized, including
carbon and nitrogen composition, water content and layer thickness of the substrate. The yields and rheological properties
of the polymers obtained under different fermentation conditions were compared. The highest succinoglycan yield was achieved
in static cultivation, reaching 42 g/l of impregnating solution, corresponding to 30 g/kg of wet substrate. The polymer production
in the horizontal bioreactor was faster, but the final yield was lower (29 g/l of impregnating solution).
Received: 26 January 1999 / Received revision: 20 April 1999 / Accepted: 23 April 1999 相似文献
20.
Fernández MJ Adrio JL Piret JM Wolfe S Ro S Demain AL 《Applied microbiology and biotechnology》1999,52(4):484-488
Growth of Streptomyces clavuligerus NP1 in the presence of methanol or ethanol resulted in a marked increase in production of cephalosporin(s) from penicillin
G by resting cells. The mycelium produced in alcohol-supplemented medium was fragmented and dispersed as compared with growth
in control medium. HPLC analysis showed that at least two products were present in the biotransformation supernatant fluid
after 1 h incubation. One of them has been identified as deacetoxycephalosporin G (DAOG).
Received: 9 December 1998 / Received revision: 29 March 1999 / Accepted: 16 April 1999 相似文献