共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Bianchi A. Bernardi A. Bosetti R. Bortolo D. Cidaria E. Crespi I. Gagliardi 《Applied microbiology and biotechnology》1997,48(3):363-366
The mutant strain Pseudomonas fluorescens TTC1 (NCIMB 40605), derived from the naphthalene-degrading Pseudomonas fluorescens N3 (NCIMB 40530), was used for the oxidation of 1- and 2-naphthols to give different isomers of dihydroxynaphthalene. The
oxidation reactions proceed through the formation of dihydrodiol intermediates, which are too unstable to be isolated, since
they spontaneously eliminate water to give the fully aromatic dihydroxynaphthalenes. The high regioselectivity of the dehydration
reaction was confirmed by the study of the acid-catalysed aromatization of a series of stable monosubstituted naphthalene
cis-1,2-dihydrodiols.
Received: 24 March 1997 / Received revision: 6 June 1997 / Accepted: 7 June 1997 相似文献
2.
N. Christiansen S. R. Christensen E. Arvin B. K. Ahring 《Applied microbiology and biotechnology》1997,47(1):91-94
Reductive dechlorination of tetrachloroethene was studied in a mesophilic upflow anaerobic sludge blanket reactor. Operating
the reactor in batch mode the dynamic transformation of tetrachloroethene, trichloroethene and dichloroethene (DCE) was monitored.
Tetrachloroethene was reductively dechlorinated to trichloroethene, which again was dechlorinated at the same rate as DCE
was produced. DCE showed a lag period of 40 h before transformation was observed. During normal reactor operation trans-1,2-DCE was the major DCE isomer, followed by cis-1,2-DCE. Small amounts of 1,1-DCE but no vinyl chloride were detected. When the influent tetrachloroethene concentration
was increased from 4.6 μM to 27 μM, the transformation rate increased, indicating that the system was not saturated with tetrachloroethene.
The main organic component in the effluent was acetate, indicating that the aceticlastic methane-producing bacteria were inhibited
by the chlorinated ethenes.
Received: 29 July 1996 / Received revision: 13 September 1996 / Accepted: 13 September 1996 相似文献
3.
J. Rabenhorst 《Applied microbiology and biotechnology》1996,46(5-6):470-474
In our screening program for microorganisms that are able to metabolize eugenol, the main component of the essential oil
of the clove tree Syzigium aromaticum (sy. Eugenia cariophyllus), we found a new Pseudomonas sp. that produces several substituted methoxyphenols when eugenol is fed to the culture. A taxonomic characterization of this
new organism has been performed. Examples of the biotransformation products, produced in high amounts, were vanillic acid
with 3.25 g/l within 99 h, ferulic acid with 5.8 g/l within 75 h and coniferyl alcohol with 3.22 g/l within 47.5 h. By changing
the culture conditions the ratio of the different metabolites could be varied. Based on these results a scheme for the degradation
of eugenol by this strain has been established.
Received: 1 April 1996 / Received revision: 24 June 1996 / Accepted: 1 July 1996 相似文献
4.
Substrate selectivity of various lipases in the esterification of cis- and trans-9-octadecenoic acid
The substrate selectivity of numerous commercially available lipases from microorganisms, plants and animal tissue towards
9-octadecenoic acids with respect to the cis/trans configuration of the CC double bond was examined by the esterification of cis- and trans-9-octadecanoic acid (oleic and elaidic acid respectively) with n-butanol in n-hexane. A great number of lipases studied, e.g. those from Pseudomonas sp., porcine pancreas or Carica papaya, were unable to discriminate between the isomeric 9-octadecenoic acids. However, lipases from Candida cylindracea and Mucor miehei catalysed the esterification of oleic acid 3–4 times faster than the corresponding reaction of elaidic acid and therefore
have a high preference for the cis isomer. Of all biocatalysts examined, only recombinant lipases from Candidaantarctica favoured elaidic acid as substrate. While the preference of Candida antarctica lipase B for the trans isomer was quite low, Candida antarctica lipase A had an extraordinary substrate selectivity and its immobilized enzyme preparation [Chirazyme L-5 (3) from Boehringer]
esterified elaidic acid about 15 times faster than oleic acid.
Received: 29 October 1998 / Received revision: 18 December 1998 / Accepted: 21 December 1998 相似文献
5.
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
6.
Addition of sodium acetate to chemically defined MP2 medium was found to increase and stabilize solvent production by Clostridium beijerinckii BA101, a solvent-hyperproducing mutant derived from C. beijerinckii NCIMB 8052. C. beijerinckii BA101 demonstrated a greater increase in solvent production than C. beijerinckii NCIMB 8052 when sodium acetate was added to MP2 medium. In 1-l batch fermentations, C. beijerinckii BA101 produced 32.6 g/l total solvents, with butanol at 20.9 g/l, when grown in MP2 medium containing 60 mM sodium acetate
and 8% glucose. To our knowledge, these values represent the highest solvent and butanol concentrations produced by a solventogenic
Clostridium strain when grown in batch culture.
Received: 29 September 1998 / Received revision: 13 February 1999 / Accepted: 26 February 1999 相似文献
7.
G. Janelt P. Bolt N. Gerbsch R. Buchholz M.-G. Cho 《Applied microbiology and biotechnology》1997,48(1):6-10
Micro-algae, especially Chlorella vulgaris, produce a range of high-value substances and the biomass itself is used for purposes such as feeding in aquaculture. A lamellar
settler was designed and built. Its suitability as a low-cost alternative to separate C. vulgaris was investigated. The settler operated semicontinuously in a laboratory photoreactor plant (total volume 9 l). A clearing
of 30%–35% and a 50% increase in harvest outflow concentration were observed. The scaled up data for design and construction
of a settler for a 200-l production plant were elaborated.
Received: 25 September 1996 / Received revision: 10 December 1996 / Accepted: 15 December 1996 相似文献
8.
The in vitro depolymerization of humic acids derived from German lignite (low-rank coal, brown coal) was studied using a
manganese peroxidase preparation from the white-rot fungus Nematoloma frowardii b19. The H2O2 required was continuously generated by glucose oxidase. Mn peroxidase depolymerized high-molecular-mass humic acids by forming
fulvic-acid-like compounds. The depolymerization process was accompanied by the decolorization of the dark-brown humic acid
fraction soluble in alkaline solutions (decrease in absorbance at 450 nm) and by the yellowish coloring of the fraction of
acid-soluble fulvic-acid-like compounds (increase in absorbance at 360 nm). The Mn peroxidase of N. frowardii b19 has been proved to be highly stable; even after an in vitro reaction time of 7 days in the presence of humic acids, less
than 10% loss in total oxidizing activity was detectable.
Received: 16 September 1996 / Received revision: 16 December 1996 / Accepted: 20 December 1996 相似文献
9.
P. E. Hessler P. E. Larsen A. I. Constantinou K. H. Schram J. M. Weber 《Applied microbiology and biotechnology》1997,47(4):398-404
A search for an abundant and economical source of isoflavones, particularly genistein, led to the discovery that the erythromycin-producing
organism Saccharopolyspora erythraea also produces this promising new cancer-prevention agent. Erythromycin fermentation is a large-scale, soybean-based process
used world-wide for the commercial production of this medically important antibiotic. Results from this study indicate that
genistin (the glucoside form of genistein), which is added to the fermentation in the soybean media, was converted to genistein
through the action of a β-glucosidase produced by the organism. Genistein was co-extracted with erythromycin from the fermentation
broth, then separated from erythromycin during the second step of the purification process for the production of erythromycin.
Received 10 September 1996 / Received revision: 22 November 1996 / Accepted: 7 December 1996 相似文献
10.
M. Graf A. Brunella M. Kittelmann K. Laumen O. Ghisalba 《Applied microbiology and biotechnology》1997,47(6):650-657
A new amidohydrolase deacetylating several N-acetyl-1-phenylethylamine derivatives (R)-specifically was found in Arthrobacter aurescens AcR5b. The strain was isolated from a wet haystack by enrichment culture with (R)-N-acetyl-1-phenylethylamine as the sole carbon source. (R) and (S )-N-acetyl-1-phenylethylamine do not serve as inducers for acylase formation. By improving the growth conditions the enzyme production
was increased 47-fold. The amidohydrolase was purified to homogeneity leading to a 5.2-fold increase of the specific activity
with a recovery of 67%. A molecular mass of 220 kDa was estimated by gel filtration. Sodium dodecyl sulfate/polyacrylamide
gel electrophorosis shows two subunits with molecular masses of 16 kDa and 89 kDa. The optimum pH and temperature were pH 8
and 50 °C, respectively. The enzyme was stable in the range of pH 7–9 and at temperatures up to 30 °C. The enzyme activity
was inhibited by Cu2+, Co2+, Ni2+, and Zn2+, and this inhibition was reversed by EDTA.M
Received: 20 September 1996 / Received version: 23 December 1996 / Accepted: 30 December 1996 相似文献
11.
A. Brunella M. Graf M. Kittelmann K. Laumen O. Ghisalba 《Applied microbiology and biotechnology》1997,47(5):515-520
Rhodococcus equi Ac6 was found to express an inducible (S )-specific N-acetyl-1-phenylethylamine amidohydrolase. Optimal bacterial growth and amidohydrolase expression were both observed around
pH 6.5. Purification of the enzyme to a single band in a Coomassie-blue-stained sodium dodecyl sulfate/polyacrylamide gel
(SDS-PAGE) was achieved by ammonium sulfate precipitation of R. equi Ac6 crude extract and column chromatographies on Fractogel TSK Butyl-650(S) and Superose 12HR. At pH 7.0 and 30 °C the amidohydrolase
had a half-life of around 350 days; at 44 °C it was only 10 min. Except for Ni2+ and, to some extent, Zn2+ and Co2+, the enzyme was neither strongly influenced by metal cations nor by chelating agents, but was inhibited by 95% at 0.1 mM
phenylmethylsulfonyl fluoride. The molecular mass of the native enzyme was estimated to be 94 kDa by gel filtration and 50 kDa
by SDS-PAGE, suggesting a dimeric structure. Specificity experiments revealed a spectrum of related N-acetylated compounds being hydrolyzed with variable enantiomeric selectivities.
Received: 20 September 1996 / Received revision: 23 December 1996 / Accepted: 30 December 1996 相似文献
12.
Poly[(R)-3-hydroxybutyric acid] (PHB) was produced at 37 °C by a recombinant Escherichia coli harboring the Alcaligenes eutrophus biosynthesis phbCAB genes in Luria-Bertani media containing glucose at 10–30 g/l at different pH values and the time-dependent changes in the
molecular mass of PHB were studied. PHB polymers accumulated within cells while glucose was present in the medium. The number-average
molecular mass of PHB decreased with time during the course of PHB accumulation, and the values for PHB were markedly dependent
on the cultivation conditions of the E. coli, ranging from 0.5 MDa to 20 MDa. Under specific conditions (pH 6.0), E. coli produced PHB with an extremely high molecular mass (20 MDa). It has been suggested that a chain-transfer agent is generated
in E. coli cells during the accumulation of PHB.
Received: 18 July 1996 / Received revision: 4 November 1996 / Accepted: 4 November 1996 相似文献
13.
K. Scheibner M. Hofrichter A. Herre J. Michels W. Fritsche 《Applied microbiology and biotechnology》1997,47(4):452-457
Within a screening program, 91 fungal strains belonging to 32 genera of different ecological and taxonomic groups (wood-
and litter-decaying basidiomycetes, saprophytic micromycetes) were tested for their ability to metabolize and mineralize 2,4,6-trinitrotoluene
(TNT). All these strains metabolized TNT rapidly by forming monoaminodinitrotoluenes (AmDNT). Micromycetes produced higher
amounts of AmDNT than did wood- and litter-decaying basidiomycetes. A significant mineralization of [14C]TNT was only observed for certain wood- and litter-decaying basidiomycetes. The most active strains, Clitocybula dusenii TMb12 and Stropharia rugosa-annulata DSM11372 mineralized 42 % and 36 % respectively of the initial added [14C]TNT (100 μM corresponding to 4.75 μCi/l) to 14CO2 within 64 days. Micromycetes (deuteromycetes, ascomycetes, zygomycetes) proved to be unable to mineralize [14C]TNT significantly.
Received: 8 August 1996 / Received revision: 16 December 1996 / Accepted: 20 December 1996 相似文献
14.
I. Besson C. Creuly J. B. Gros C. Larroche 《Applied microbiology and biotechnology》1997,47(5):489-495
2,5-Dimethylpyrazine (2,5-DMP) and tetramethylpyrazine (TTMP) were produced using Bacillus subtilis IFO 3013 grown on soybeans. Solid-state cultivations were carried out either in 100-ml bottles or in a fixed-bed column reactor,
both systems being at 27 °C. Optimization studies showed that the best way to produce the two above aroma compounds involved
two separate processes. 2,5-DMP was obtained using soybeans enriched with 75 g threonine/kg initial dry weight (i.d.w.), giving
0.85 g metabolite/kg i.d.w. after 6 days. TTMP production involved addition of 90 g/kg i.d.w. acetoin to soybeans, and 2.5 g/kg
i.d.w. was recovered after 14 days. These results demonstrated the suitability of solid-state cultivation for production of
high-added-value compounds.
Received: 30 September 1996 / Received revision: 23 December 1996 / Accepted: 30 December 1996 相似文献
15.
Aromatic and heterocyclic aldehydes may be produced by the mandelate pathway of Pseudomonas putida ATCC 12633 via the biotransformation of benzoyl formate and substrate analogues. Under optimised biotransformation conditions
(37 °C, pH 5.4) and with benzoyl formate as a substrate, benzaldehyde may be accumulated with yields above 85%. Benzaldehyde
is toxic to P. putida ATCC 12633; levels above 0.5 g/l (5 mM) reduce the biotransformation activity. Total activity loss occurs at an aldehyde
concentration of 2.1 g/l (20 mM). To overcome this limitation, the rapid removal of the aldehyde is desirable via in situ product removal. The biotransformation of benzoyl formate (working volume 1 l) without in situ product removal accumulates 2.1 g/l benzaldehyde. Benzaldehyde removal by gas stripping produces a total of 3.5 g/l before
inhibition. However, the most efficient method is solid-phase adsorption using activated charcoal as the sorbant, this allows
the production of over 4.1 g/l benzaldehyde. Addition of bisulphite as a complexing agent causes inhibition of the biotransformation
and bisulphite is therefore is not suitable for in situ product removal.
Received: 16 March 1998 / Received revision: 20 May 1998 / Accepted: 21 May 1998 相似文献
16.
J. M. Obón J. R. Maiquez M. Cánovas H.-P. Kleber J. L. Iborra 《Applied microbiology and biotechnology》1999,51(6):760-764
The use of a biological procedure for l-carnitine production as an alternative to chemical methods must be accompanied by an efficient and highly productive reaction
system. Continuous l-carnitine production from crotonobetaine was studied in a cell-recycle reactor with Escherichia coli O44 K74 as biocatalyst. This bioreactor, running under the optimum medium composition (25 mM fumarate, 5 g/l peptone), was
able to reach a high cell density (26 g dry weight/l) and therefore to obtain high productivity values (6.2 g l-carnitine l−1 h−1). This process showed its feasibility for industrial l-carnitine production. In addition, resting cells maintained in continuous operation, with crotonobetaine as the only medium
component, kept their biocatalytic capacity for 4 days, but the biotransformation capacity decreased progressively when this
particular method of cultivation was used.
Received: 10 December 1998 / Received revision: 19 February 1999 / Accepted: 20 February 1999 相似文献
17.
Vanderberg LA Krieger-Grumbine R Taylor MN 《Applied microbiology and biotechnology》2000,53(4):447-452
Rhodococcus rhodochrous strain OFS grew on toluene as a sole source of carbon and energy with a maximum growth rate of 0.011 h−1. Initial reaction products were extracted, derivatized and identified by GC-MS. Oxygen consumption studies indicated that
OFS grown on an aliphatic substrate required an induction period before oxidizing toluene. OFS grown on toluene transformed
an array of aromatic ground water pollutants including styrene, ethylbenzene and chlorobenzene. Products of these transformations
were identified. The sole product of chlorobenzene biotransformation was 4-chlorophenol. Products from toluene oxidation included
3- and 4-methylcatechol as well as benzyl alcohol, p-cresol and cis-toluene dihydrodiol. The identification of these and the products of other aromatic substrate conversions affirm that oxidation
occurred on the functional group as well as directly on the aromatic nucleus.
Received: 23 July 1999 / Received revision: 4 October 1999 / Accepted: 16 October 1999 相似文献
18.
Pilot-scale production of butanol by Clostridium beijerinckii BA101 using a low-cost fermentation medium based on corn steep water 总被引:3,自引:0,他引:3
To improve the economic competitiveness of the acetone/butanol/ethanol fermentation process, glucose/corn steep water (CSW)
medium was used on a pilot scale for the production of solvents. The production of butanol by the Clostridium beijerinckii NCIMB 8052 parent strain and the solvent-hyperproducing BA101 mutant was compared. In a 20-l fermentation using 5% glucose/CSW
medium, C. beijerinckii 8052 produced 8.5 g butanol/l and 5 g acetone/l, while C. beijerinckii BA101 produced 16 g butanol/l and 7.5 g acetone/l. Further studies were carried out on a larger scale using an optimized
6% glucose/CSW medium. In a 200-l pilot-scale fermentor, C. beijerinckii 8052 produced 12.7 g butanol/l and 6 g acetone/l following 96 h of fermentation. C. beijerinckii BA101 produced 17.8 g/l and 5.5 g/l butanol and acetone respectively, following 130 h of fermentation. These results represent
a 40% increase in final butanol concentration by the C. beijerinckii BA101 mutant strain when compared to the 8052 parent strain. The total solvents (acetone, butanol, and ethanol) produced
by C. beijerinckii NCIMB 8052 and BA101 in a 200-l fermentation were 19.2 g/l and 23.6 g/l respectively. This is the first report of pilot-scale
butanol production by the solvent-hyperproducing C. beijerinckii BA101 mutant employing an inexpensive glucose/CSW medium.
Received: 26 May 1998 / Received revision: 21 September 1998 / Accepted: 11 October 1998 相似文献
19.
We have used the polymerase chain reaction (PCR) method to monitor meiotic recombination in the basidiomycete Coprinus cinereus. We used DNA-mediated transformation to recover strains with modifications of the trp1 locus. The modifications were designed to introduce unique PCR priming sites separated by a homologous 2.4 kb region in which
crossing over could occur. We showed that exchange occurred in this region at the frequency expected for a typical region
of this genome (2.4 kb should correspond to a genetic length of 0.08 cM). We also detected products resulting from crossing
over in DNAs extracted from cells in meiotic prophase. The assay should be useful for monitoring exchange in mutants that
cannot complete meiosis.
Received: 5 September 1996 / Accepted: 1 December 1996 相似文献
20.
A.-M. Davila R. Marchal J.-P. Vandecasteele 《Applied microbiology and biotechnology》1997,47(5):496-501
Sophorose lipid production by Candida bombicola is a two-step process where sophorose lipids are mainly produced after a first stage of growth, ending because of nitrogen
limitation. The influence of the following parameters was individually studied for both the stages of growth and of product
formation with respect to final sophorose lipid production performance: pH, temperature and carbon source. Glucose and rapeseed
ethyl esters were supplied individually or as a dual carbon source. The lipidic substrate was added by continuous feeding.
It was found that supplying both carbon sources during the production step was crucial for obtaining a high production performance
ranging from 250 g l−1 to 300 g l−1 or more. Controlling the feeding of rapeseed ethyl esters to avoid inhibition by fatty acids was essential for a successful
scale-up of the fermentation on the industrial scale. The conditions of substrate feeding markedly affected the composition
of the mixture of sophorose lipids produced, namely the extent of acetylation of the sophorose moieties and distribution of
the acidic and lactonic forms. The results suggest that the physiological role of sophorose lipid production is related to
the regulation of energy metabolism.
Received: 26 June 1996 / Received revision: 12 December 1996 / Accepted: 15 December 1996 相似文献