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  • 1
    ISSN: 1476-5535
    Keywords: antibiotic ; fermentation ; microbial transformation ; hydroxylation ; aurodox ; heneicomycin ; Streptomyces goldiniensis ; Streptomyces filippiniensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Streptomyces sp GE44282 was isolated in the course of a screening program for novel antibiotics. It co-produces heneicomycin and aurodox, two kirromycin-type antibiotics, which differ by the presence of an hydroxyl group at the C30 position of aurodox. Heneicomycin is converted into aurodox both by growing and resting cells ofStreptomyces sp GE44282 and by the producer of aurodox,Streptomyces goldiniensis ATCC 21386. This bioconversion of heneicomycin is substrate-specific and is not observed using the producer of heneicomycin,Streptomyces filippiniensis NRRL 11044. The three strains show very similar taxonomic characteristics. These results suggest that heneicomycin is a precursor of aurodox, the production of which depends on the bioconversion capability expressed by the strain.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1476-5535
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-5535
    Keywords: Cloning vector construction ; Expression ; Zymomonas mobilis ; Isolation of promoters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Broad host range plasmids have previously been shown to be suitable as vectors to introduce antibiotic resistance genes intoZ. mobilis. However, attempts to use these vectors to carry other genes with enteric promoters and controlling elements have resulted in limited success due to poor expression. Thus we have constructed a promoter cloning vector in a modified pBR327 and used this vector to isolated 12 promoters fromZ. mobilis which express various levels of β-galactosidase inEscherichia coli. Four of these were then subcloned into pCVD 305 for introduction intoZ. mobilis. All expressed β-galactosidase inZ. mobilis with activities of 100 to 1800 Miller units. One of these retained aBamHl site into which new genes can be readily inserted immediately downstream from theZ. mobilis promoter. Genetic traits carried by pCVD 305 were initially unstable but spontaneous variants were produced during sub-culture in which the plasmid was resistant to curing at elevated temperature. One of these variants was examined in some detail. The increased stability of this variant appears to result from an alteration in the plasmid rather than a chromosomal mutation or from chromosomal integration.
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  • 4
    ISSN: 1476-5535
    Keywords: Lincosaminides ; Lincomycin ; Pirlimycin ; Clindamycin ; Inactivation ; Nucleotidylylation ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Fermentations ofStreptomyces coelicolor are known to convert lincosaminide antibiotics to mixtures of their inactive 3-(5′-ribonucleotides). In the present study, lincomycin, clindamycin and pirlimycin were nucleotidylylated and inactivated using crude enzyme preparations ofS. coelicolor. Optimal conversion is known to occur near pH 6 and to require Mg2+ and nucleoside 5′-triphosphates. In descending order of activity, inosine, adenosine, guanosine, cytidine and uridine 5′-triphosphates functioned as cofactors in these nucleotidylylations. In all instances, 90% of maximal conversion occurred within 24 h. When reaction rates were investigated as functions of enzyme protein addition, pirlimycin appeared to be the superior lincosaminide substrate. Antibiotic activities of these inactivation products could be regenerated through the action of phosphodiesterase, EC 3.1.4.1.
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  • 5
    ISSN: 1476-5535
    Keywords: Xanthan ; Xanthan degradation ; Biodegradation ; Salt-tolerant bacteria ; Bacillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Three salt-tolerant bacteria which degraded xanthan were isolated from various water and soil samples collected from New Jersey, Illinois, and Louisiana. The mixed culture, HD1, contained aBacillus sp. which produced an inducible enzyme(s) having the highest extracellular xanthan-degrading activity found. Xanthan alone induced the observed xanthan-degrading activity. The optimum pH and temperature for cell growth were 5–7 and 30–35°C, respectively. The optimum temperature for activity of the xanthan-degrading enzyme(s) was 35–45°C, slightly higher than the optimum growth temperature. With a cell-free enzyme preparation, the optimum pH for the reduction of solution viscosity and for the release of reducing sugar groups were different (5 and 6, respectively), suggesting the involvement of more than one enzyme for these two reactions. Products of enzymatic xanthan degradation were identified as glucose, glucuronic acid, mannose, pyruvated mannose, acetylated mannose and unidentified oligo- and polysaccharides. The weight average molecular weight of xanthan samples shifted from 6.5·106 down to 6.0·104 during 18 h of incubation with the cell-free crude enzymes. The activity of the xanthan-degrading enzyme(s) was not influenced by the presence or absence of air or by the presence of Na2S2O4 and low levels of biocides such as formaldehyde (25 ppm) and 2,2-dibromo-3-nitrilopropionamide (10 ppm). Formaldehyde at 50 ppm effectively inhibited growth of the xanthan degraders.
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  • 6
    ISSN: 1476-5535
    Keywords: Cyclosporine ; Cyclosporin A ; Tolypocladium inflatum ; Process optimization ; Strain improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The new immunosuppressive agent cyclosporine (Cyclosporin A, Cy) is the most prominent member of a group of cyclic peptide fungal metabolites (cyclosporins) produced byTolypocladium inflatum in submerged fermentations. In the present study, kinetics and physiology of mycelial growth and Cy production byT. inflatum were examined. A new semi-synthetic medium was formulated, consisting of a single carbon/energy source, Bacto-peptone, potassium phosphate and potassium chloride. A wide variety of carbon sources supported growth and Cy production. 3% (w/v) sorbose gave the highest final Cy titer (105.5 mg/l), based on 10-day fermentations. The best specific Cy production was observed with 2% sorbose (14.3 mg Cy/g biomass) followed by 5%myo-inositol (13.4 mg Cy/g biomass). A feeding strategy consisting of sequential addition of two carbon sources such as sorbose and maltose was developed in order to reach higher volumetric production. Genetic studies were also conducted, focussing on the development of mutants for increased Cy production and for the synthesis of novel cyclosporins. In the course of these studies, viable protoplasts ofT. inflatum have been isolated and regenerated.
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  • 7
    ISSN: 1476-5535
    Keywords: Clostridium acetobutylicum ; Alpha-amylase ; Glucoamylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary An examination into the effect of different carbohydrate sources indicated that the production of extracellular alpha-amylase and glucoamylase was under similar biosynthetic control inClostridium acetobutylicum SA-1. Cell-associated starch-hydrolytic enzymes may be more important than extracellular enzymes in the processing of the starch molecule.
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  • 8
    ISSN: 1476-5535
    Keywords: Heat injury ; Staphylococcus aureus ; Glucose effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Staphylococcus aureus 196E, when grown in a glucose (≥0.25% wt./vol.)-containing medium, produced cells that would undergo injury when subjected to sublethal heat conditions (45 min at 50°C); however, if glucose was omitted from the growth medium, the extent of injury was greatly reduced. Media containing glucose sterilized by filtration or by separate autoclaving produced cells equal in injury susceptibility to medium in which glucose was autoclaved as part of the medium components. Injury also occurred when other sugars such as fructose, mannose, maltose, or lactose were substituted for glucose. Sugar-containing media that producedStaphylococcus aureus of maximal susceptibility to heat injury reached a pH of approximately 6 or lower during growth of the cells. Incubation of staphylococci in growth medium acidified with acetic or lactic acids or HCl did not lead to cells that would undergo injury under the stated conditions. The stimulatory effect of glucose on injury appears to be related to the metabolism of the sugar byStaphylococcus aureus.
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  • 9
    ISSN: 1476-5535
    Keywords: protoplast fusion ; killer character ; flocculence ; Saccharomyces cerevisiae ; industrial yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Conditions were optimized for rapid release and improved regeneration of protoplasts ofSaccharomyces cerevisiae NCIM 3458. Rapid protoplast release was also obtained with representatives of several other yeast genera under the modified conditions of treatment. The application of the procedure in construction of a highly flocculentSaccharomyces cerevisiae with a killer character is described. Fusion was effected between UV-killed protoplasts ofS. cerevisiae NCIM 3578 with a killer character and live protoplasts of the highly flocculentS. cerevisiae NCIM 3528 in the presence of polyethylene glycol (PEG) 6000. Fusants were selected using benomyl resistance as marker, the killer toxin producer rather than the highly flocculent yeast being resistant to the fungicide at a concentration of 100 μg ml−1. Fusants were also characterized by their DNA contents, capacity for ethanolic fermentation of molasses sugar and levels of invertase, alcohol dehydrogenase and pyruvate decarboxylase activities.
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  • 10
    ISSN: 1476-5535
    Keywords: impedance ; D-value ; cosmetic preservative ; P. aeruginosa ; screening method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An efficient impedance method was developed for rapid evaluation of cosmetic preservatives. The method used decimal reduction time or D-value to assess preservative efficacies. The D-value, which was calculated from the plot of Log CFU ml−1 versus time by linear regression analysis, could be obtained within 48 h. Thus, the time required for the challenge test was reduced from 4–8 weeks with the standard procedures (eg US Pharmacopeia), to 2 days with the current method. A calibration curve (r=-0.95) was established by plotting the Log CFU ml−1 versus capacitance detection time (DT) of 108 samples. With the calibration, CFU can be estimated directly from the impedance test without plating. Two commercial biocides and several other chemicals were evaluated in a shampoo by the impedance procedure againstPseudomonas aeruginosa. The D-values obtained from the impedance test were not significantly different from those produced by the conventional plate count method. The technique was found to be particularly useful when screening a large number of compounds to find novel preservatives and synergistic preservative combinations.
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