摘要:

AbstractLocalisation of endo β‐1‐4‐xylan xylanohydrolase and β‐xylosidase was studied inChaetomium globosumwhen the fungus was grown on 1% (w/v) birchwood xylan. Although both enzymes are present in the soluble fraction of the cell, xylanase activity was membrane bound whereas β‐xylosidase activity was associated with the cell wall. Xylanase and β‐xylosidase acted synergistically on the xylan backbone with the appearance of xylo‐oligosaccharides, xyl

ISSN:0233-111X    

DOI:10.1002/jobm.3620370202

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe effect of some medium components, viscous substances and metabolic inhibitors, on catalase production by mutantAspergillus nigerhas been studied in shake culture. Altering the composition of the basal medium, particularly substituting NaNO3for KNO3, and peptone for yeast extract brought an increase in extra‐ and intracellular catalase activity by 1.5‐ and 3‐fold, respectively. The addition of 2.0–6.0 mg sodium alginate or pectin/ml as viscous additive to the medium, containing glucose as carbon source, increased the medium viscosity and catalase production in shake culture by about 2.8‐ to 3.0‐fold. The highest yield of extracellular catalase activity ofA. nigerwas obtained in the presence of sodium orthovanadate and Triton X‐100, which improved the activity of this enzyme by about 1.5‐2.2‐fold. A significant increase in intracellular catalase activity was observed in the presence of hematin, Tween 80 and sodium orthovanadate (1.7‐, 1.6‐ and 1.4‐fold respectively). The time course of growth and enzyme production byA. nigerin the optimized

ISSN:0233-111X    

DOI:10.1002/jobm.3620370203

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractExoglucanase and endoglucanase (glucanases) enzymes ofS. albaduncuswere found to be very stable, showing only 36% and 8% loss in activities respectively after 3 days of incubation at 50 °C. In contrast, β‐glucosidase was significantly less stable retaining only 22.30% activity after 30 min incubation at 40 °C. The glucanases manifested maximum stability in pH range of 5.5–6.0 whereas β‐glucosidase was completely stable over a broad pH range of 6.5–9.0. Both glucanases were enhanced by some cations whereas β‐glucosidase did not require any cation for activity.Kmvalues for crude exoglucanase, endoglucanase and β‐glucosidase were 40.00 mg/ml, 92.30 mg/ml and 1.714 mM with maximum reaction velocities (Vmax) of 0.606, 33.330 and 0.109 IU/mg of protein, respectively. The enzymes were subject to end‐product inhibition, with exo‐ and endo‐glucanases decreasing by 20% and 70% respectively, in the presence of 0.3% glucose. However, β‐glucosidase showed marked resistance to glucose inhibition, retaining 59% of residual activity even in the presence of 30% glucose in the reaction mixture. This characteristic may be advantageous in the commercial exploitation of enzyme system. An activation of β‐glucosidase at lower concentrations of glucose su

ISSN:0233-111X    

DOI:10.1002/jobm.3620370204

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe transport and phosphorylation of gluconate inE. colioccurs through two systems (GntI and GntII) which duplicate activities.bioH‐asddeletion mutants do not grow on media with gluconate as sole carbon source because they lack the GntI system and do not express GntII. AlthoughE. coliC177 is a Δ(bioH‐asd) mutant, it carries thepyrB linked mutationgnt177 that enables it to metabolize this substrate through inducible expression of the GntII system. SeveralgntS derivatives which are unable to grow on gluconate were isolated fromE. coliC177 by spontaneous curing of the transposon Tn10 previously inserted at thegntSlocus(zjf::Tn10, min 95.3). A representativegntS mutant,E. coliTI141A retained the ability to take up gluconate but had lost the thermosensitive gluconokinase activity (genegntV, min 96.9). Furthermore, it could be demonstrated thatgntV is repressed inE. coliTI141A. The results indicate thatgntS might specify a trans‐acting positive regulator involved in the control of at least the expression of the thermosensitive gluconokinase (GntII), instead of a gluconate uptake system as it was previously postulated. Likewise, these results can be used to reconsider whether thelocusaltered by thegnt177 lesion is allelic with that of the GntII permease instead of a regulator, as it was originally post

ISSN:0233-111X    

DOI:10.1002/jobm.3620370205

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractVarious methods for the isolation of periplasm were examined and compared with regard to the complete release of known periplasmic marker enzymes and the contamination of the periplasm by cytosol forPseudomonas aeruginosaPAO1 as a significant Gram‐negative test strain. The aim of the investigations was to clarify the exact localization of alanyl aminopeptidase (AAP) and leucyl aminopeptidase (LAP) of this microorganism and to evaluate these methods.The osmotic shock of NOSSALand HEPPEL(1996) was the most effective method with the lowest contamination by the cytosolic marker enzyme malic enzyme, but some proteins, which are located near the inner side of the cytoplasmic membrane, can be released additionally into the periplasm. All other procedures like chloroform or polymyxin treatment, the magnesium chloride washing of intact bacteria and spheroblasting by lysozyme in the presence of EDTA or magnesium chloride resulted only in a partial, sometimes only very low release of periplasm. The periplasmic enzymes are bound either more by hydrophobic or more by ionic interactions to the cell envelope and show a different behaviour with the different releasing agents. These methods are useful for a further differentiation between really periplasmic proteins and those proteins, which were false positive found in periplasm as a result of the osmotic shock. Our results show that AAP fromPseudomonas aeruginosais a periplasmic enzyme with hydrophobic interactions to the cytoplasmic membrane, corresponding to the early results of LAZDUNSKIand MURGIERforEscherichia coli(LAZDUNSKIet al. 1975a and b, MURGIERet al. 1977), and LAP is cytosolic, but located near the cytoplasmic membrane. The AAP is not a real amphipatic membrane protein, as could be demonstrated by phase separation experiments with Triton X‐

ISSN:0233-111X    

DOI:10.1002/jobm.3620370206

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractDiversity within bacteria isolated from activated sludge and the Baltic sea and recognized by the rRNA targeted oligonucleotide probe ppT (designed by BRAUN‐HOWLANDet al., 1993 to recognizeC. testosteroni) was studied. The partial nucleotide sequences of 16S genes of the isolates revealed that the activated sludge and Baltic sea isolates each formed a separate group distinct fromC. testosteroni.The analysis of phage and bacteriocin sensitivity as well as whole cell protein patterns revealed the same grouping, but in these characters also intragroup variation was observed. As a conclusion, neither of the studied groups wereC. testosteroni, but they probably belong to two previously unknown species common in activated sludge or the Baltic se

ISSN:0233-111X    

DOI:10.1002/jobm.3620370207

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractCytochrome P‐450 was detected in microsomes and presumably in cytosol ofNeurospora crassa, and was found to be inducible by progesterone. In the microsomal fraction cytochrome b5 and NADPH‐cytochrome c reductase activities were measurable, too. Cytochrome P‐450 ofNeurospora crassais inhibited by SKF‐525 A and by inhibitors of ergosterol biosynthesis. After induction of cytochrome P‐450 with progesterone 11α‐hydroxyprogesterone as one metabolite of progesterone was detected in the culture media as well as in the mycelia. After 42 hours about 70% of progesterone were

ISSN:0233-111X    

DOI:10.1002/jobm.3620370208

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe influnce of UV‐B irradiance was examined on three strains of a cyanobacterium,Anacystis nidulans.These include wild typeA. nidulans(An) and strains resistant to cadmium (Cdr) and cyanophage As‐1 (As‐1r). The results indicated that although, the UV‐B radiation considered in the present study was damaging to all the three strains, As‐1roffered some degree of protection from UV‐B as far as changes in chlorophyll, phycocyanin,14CO2uptake and photosynthetic O2evolution were concerned. Cadmium resistant strain appeared to be most sensitive to UV‐B among the three. The observations form the first report of UV‐B effects on a metal resistant and a cyanophage resistant strain of

ISSN:0233-111X    

DOI:10.1002/jobm.3620370209

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620370201

出版商:Wiley‐VCH    

年代:1997

数据来源: WILEY