RESUMEN
AIMS: In order to investigate the mechanism of bacterial resistance to surfactants, a spontaneous mutant of Escherichia coli, OW66, resistant to a cationic surfactant cetyltrimethylammonium bromide (CTAB), was isolated and its physiological properties analysed. METHODS AND RESULTS: Strain OW66 grew in M9 medium containing CTAB at 45 micromol l(-1), whereas its parent strain, OW6, did not, even at 15 micromol l(-1). The mutant was also resistant to some other surfactants, antibiotics, heavy metals, organic solvents and oxidants examined. To determine the differences in physiology between strains OW66 and OW6, the compositions of their cell surface structures were analysed. In strain OW66, the relative content of OmpC in particular was higher than that of OmpF, whereas a reverse situation was seen in OW6 strain. The lipopolysaccharide (LPS) profile was different between these strains, and altered LPS in strain OW66 was suggested to be involved in the resistance to CTAB. CONCLUSIONS: A CTAB-resistant E. coli isolate possesses an altered outer membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: Treatment with a relatively low concentration of CTAB was found to introduce multi-drug resistance into bacterial cells. This acquired resistance should be taken into account with the frequent use of surfactants in industries and various environments.
Asunto(s)
Compuestos de Cetrimonio/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Tensoactivos/farmacología , Proteínas Bacterianas/análisis , Cetrimonio , Escherichia coli/química , Escherichia coli/aislamiento & purificación , Lipopolisacáridos/análisis , Pruebas de Sensibilidad Microbiana , Fosfolípidos/análisisRESUMEN
The enantioselectivity of ECAA to ECHB by eight fungi of four genus was evaluated. All strains showed (S)-selectivity, and Cylindrocarpon sclerotigenum IFO 31855 gave the highest yield and good optical purity (e.e.; >99%). Cell-free extract and acetone-dried cells of C. sclerotigenum IFO 31855 reduced ECAA to (S)-ECHB in the presence of NADPH (e.e.; >99%) and the e.e. was not decreased by heat treatment of the cell-free extract or the acetone-dried cells. The active fractions shown by two peaks on a DEAE-Toyopearl 650 M column gave preferentially (S)-ECHB (e.e.; >99%).
Asunto(s)
Acetoacetatos/metabolismo , Hongos/metabolismo , Acetoacetatos/química , Biotransformación , Butiratos/química , Butiratos/metabolismo , Hypocreales/metabolismo , Cinética , Oxidación-Reducción , EstereoisomerismoRESUMEN
Seven fungi, which are found to reduce ethyl 3-oxobutanoate in high yields, were tested for their reducing ability for ethyl 2-methyl 3-oxobutanoate. We obtained some interesting findings. In particular, Penicillium purpurogenum reduced ethyl 2-methyl 3-oxobutanoate to the corresponding alcohols with the diastereomer (anti/syn) ratio of 93/7 with the enantiomeric excess of anti-(2S,3S)- and syn-(2S,3R)- hydroxy esters of 90 and >99 ee%, respectively.
Asunto(s)
Butiratos/metabolismo , Hongos Mitospóricos/metabolismo , Aspergillus/metabolismo , Fusarium/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Espectroscopía de Resonancia Magnética , Penicillium/metabolismo , Trichoderma/metabolismoRESUMEN
Chlorella pyrenoidosa Chick reduced ethyl 2-methyl 3-oxobutanoate to the corresponding alcohols with the diastereomer (anti/syn) ratio of 53/47. The enantiomer excesses of anti-(2S, 3S)- and syn-(2S, 3R)-hydroxy esters were 89 and > 99ee% respectively. C. vulgaris and C. regularis afforded predominantly the syn-isomer, contrary to C. pyrenoidosa. The differences in the activity of reducing ethyl 2-methyl 3-oxobutanoate were observed among three strains of Chlorella. Addition of 2% metal salts slightly increased the chemical yield of the hydroxy ester.
Asunto(s)
Butiratos/química , Chlorella/química , Oxidación-Reducción , EstereoisomerismoRESUMEN
Using a calorimeter with 24 sample units the heat evolved during incubation of yeast cultures at 30 degrees C was detected in the form of growth thermograms. Ethanol and methanol added to the culture medium produced changes in the growth thermograms that could be analyzed to calculate the 50% inhibitory concentration (Ki) and minimum inhibitory concentration (MIC). Correlation of the heat evolution curves with the number of cells and the turbidity of the culture was found to be very good. It was found that addition of ethanol and methanol up to 7.65% had clear effects of inhibition on growth of all yeast strains studied, reducing the growth rate constant and delaying growth. However, the amounts of ethanol produced from the nutrients available in the culture vial was only little affected by the initial addition of up to 7.65% (v/v) of ethanol or methanol in the medium.
Asunto(s)
Etanol/farmacología , Metanol/farmacología , Levaduras/efectos de los fármacos , Calorimetría , Etanol/metabolismo , Cinética , Pruebas de Sensibilidad Microbiana , Levaduras/crecimiento & desarrolloRESUMEN
Aspergillus fumigatus ATCC 28282 converted phenylacetic acid into a new dihydroxylated compound (2,6-dihydroxyphenylacetic acid) which was identified as 2,6-dimethoxyphenylacetic acid methyl ester. Two other new metabolites have been isolated also and identified as orthohydroxyphenylacetic acid and meta-hydroxyphenylacetic acid.