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Control of temperature-dependent synthesis of K99 fimbriae (1990)

Woude, Marjan W. ; Braster, Martin ; Verseveld, Henk W. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology letters 68 (1990), S. 0

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ISSN: 1574-6968

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Abstract The influence of temperature on the production of K99 fimbriae by Escherichia coli was determined in cultures growing at constant specific growth rate in continuous cultures. In a wild type strain, in which the K99 operon is present on a low copy number plasmid, low cultivation temperature repressed the K99 production. This temperature-dependent production was not observed after introduction of multicopies of the regulatory region of the K99 operon into this strain, nor in E. coli K12 harbouring a recombinant, multicopy plasmid encoding the K99 operon. These results are in agreement with a regulation model in which a regulatory factor, most likely a repressor, inhibits expression of the K99 operon at low temperatures.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04146.x

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16S rDNA-based characterization of BTX-catabolizing microbial associations isolated from a South African sandy soil (2000)

Ralebitso, Theresia K. ; Röling, Wilfred F. M. ; Braster, Martin ; [et al.]

Springer

Biodegradation 11 (2000), S. 351-357

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ISSN: 1572-9729

Keywords: BTX ; environmental parameter variations ; microbial profiles ; PCR-DGGE

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract In the presence of different selection pressures, particularly pHand electron donor concentration, indigenous microbial associations which catabolize selected petroleum hydrocarbon components (benzene, toluene and o-, m- and p-xylene (BTX)) were enriched and isolated from a petroleum hydrocarbon-contaminated KwaZulu-Natal sandy soil. Electron microscopy revealed that, numerically, rods constituted the majority of the populations responsible for BTX catabolism. Molecular techniques (polymerase chain reaction (PCR) and 16S rDNA fingerprinting by denaturing-gradient gel electrophoresis (DGGE)) were employed to explore the diversities and analyze the structures of the isolated microbial associations. Pearson product-moment correlation indicated that the different, but chemically similar, petroleum hydrocarbon molecules, effectedthe isolation of different associations. However, some similar numerically-dominant bands characterized the associations. A 30% similarity was evident between the m- and o-xylene-catabolizing associations regardless of the molecule concentration and the enrichment pH. PCR-DGGE was also used to complement conventional culture-based microbiological procedures for environmental parameter optimization. Band pattern differencesindicated profile variations of the isolated associations which possibly accounted for the growth rate changes recorded in response to pH and temperature perturbations.