Browsing by Author "GONZALEZ, B"

Now showing 1 - 13 of 13
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    BENZALDEHYDE LYASE, A NOVEL THIAMINE PPI-REQUIRING ENZYME, FROM PSEUDOMONAS-FLUORESCENS BIOVAR-I
    (1989) GONZALEZ, B; VICUNA, R
    Pseudomonas fluorescens biovar I can grow on benzoin as the sole carbon and energy source. This ability is due to benzaldehyde lyase, a new type of enzyme that irreversibly cleaves the acyloin linkage of benzoin, producing two molecules of benzaldehyde. Benzaldehyde lyase was purified 70-fold and found to require catalytic amounts of thiamine PPi (TPP) and a divalent cation as cofactors. Optimal activity was obtained with a 1.0 mM concentration of Mn2+, Mg2+, or Ca2+. Gel permeation chromatography indicated a native molecular weight of 80,000, whereas the enzyme migrated in sodium dodecyl sulfate-containing polyacrylamide gels as a single polypeptide with a molecular weight of 53,000. Benzaldehyde lyase is highly specific; of a variety of structurally related compounds tested, only benzoin and benzoin and anisoin (4,4''-dimethoxybenzoin) acted as substrates, their apparent Kms being 9.0 .times. 10-3 and 3.25 .times. 10-2 mM, respectively. A catalytic mechanism for the enzyme is proposed.
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    BIOCHEMICAL AND GENETIC-STUDIES OF BACTERIA METABOLIZING LIGNIN-RELATED COMPOUNDS
    (1988) VICUNA, R; GONZALEZ, B; RUTTIMANN, C; SAPAG, A; SEELENFREUND, D
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    DEGRADATION OF 4,5-DICHLOROGUAIACOL BY SOIL-MICROORGANISMS
    (1995) GONZALEZ, B; BREZNY, R; HERRERA, M; JOYCE, TW
    No microorganisms could be isolated from chemostats or from a soil column fed with 4,5-dichloroguaiacol as the only carbon source. If guaiacol was added to chemostats with 4,5-dichloroguaiacol, either soil microbial consortia or guaiacol-degrading bacteria could dechlorinate the 4,5-dichloroguaiacol provided it was < 0.2 mM. A microbial consortium from farm soil removed 4,5-dichloroguaiacol under aerobic or anoxic conditions, with or without chlorolignin. Dichlorocatechol was the only 4,5-dichloroguaiacol-derived metabolite detected. In aerobic incubations, 4,5-dichlorocatechol was further degraded whereas under anoxic conditions it accumulated.
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    DEGRADATION OF DIARYLETHANE STRUCTURES BY PSEUDOMONAS-FLUORESCENS BIOVAR-I
    (1988) GONZALEZ, B; OLAVE, I; CALDERON, I; VICUNA, R
    Pseudomonas fluorescens biovar I was isolated from a pulp mill effluent based on its ability to grow on synthetic media containing 1,2-diarylethane structures as the sole carbon and energy source. Analysis of samples taken from cultures of this strain in benzoin or 4,4''-dimethoxybenzoin (anisoin), showed that cleavage between the two aliphatic carbons takes place prior to ring fission. Intermonomeric cleavage was also obtained with crude extracts. Substrates of this reaction were only those 1,2-diarylethane compounds that supported growth of the bacterium. The purification and partial characterization of an enzyme that catalyzes the NADH-dependent reduction of the carbonyl group of benzoin and anisoin is also reported.
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    DEGRADATION OF TRICHLOROPHENOLS BY ALCALIGENES-EUTROPHUS JMP134
    (1995) CLEMENT, P; MATUS, V; CARDENAS, L; GONZALEZ, B
    The degradation of chlorophenols by Alcaligenes eutrophus JMP134 (pJP4) was studied. The strain grew on 2,4,6-trichlorophenol or 2,4,6-tribromophenol as the sole carbon and energy source. Complete degradation of 2,4,6-trichlorophenol was confirmed by chloride release and gas chromatography analysis of supernatants from growth cultures. The 2,3,5-, 2,3,4-, 2,3,6- and 2,4,5-isomers of trichlorophenol did not support growth. However, up to 40% of 2,4,5-trichlorophenol was mineralized during growth of A. eutrophus on chemostats fed with either phenol (0.4 mM) or 2,4,6-trichlorophenol (0.4 mM) plus 2,4,5-trichlorophenol (0.1 mM). Growth on 2,4,6-trihalophenols was also observed in A. eutrophus JMP222, the strain lacking pJP4, suggesting that this new degradative ability reported for A. eutrophus is not related to pJP4 encoded catabolic functions.
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    ELECTRON-MICROSCOPIC MAPPING OF THERMUS-THERMOPHILUS RNA-POLYMERASE BINDING-SITES ON PLASMID PBR322
    (1985) GONZALEZ, B; DAVAGNINO, J; VICUNA, R
    The binding of RNA polymerase from the extreme thermophile T. thermophilus HB8 to plasmid pBR322 was measured by EM. DNA-protein complexes were prepared at 35 and 60.degree. C. At both temperatures the enzyme binds strongly to sites which coincide with promoters P1, P2, P3 and P4 present in pBR322. At 60.degree. C, an additional binding site appears, which is located between P3 and P4. There is a high degree of correlation between RNA polymerase binding sites and the location of A-T rich regions on pBR322 DNA.
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    ELECTRON-MICROSCOPY MAPPING OF ESCHERICHIA-COLI RNA POLYMERASE-BINDING SITES ON PLASMIDS FROM THERMOPHILIC BACTERIA
    (1984) GONZALEZ, B; VASQUEZ, C; BULL, P; VICUNA, R
    The binding sites of E. coli RNA polymerase to plasmid DNA from extremely thermophilic bacteria were mapped by EM. Templates used in these studies included plasmids pTF62 (from Thermus flavus AT62) and pTT8 (from T. thermophilus HB8) and hybrid molecules constructed by ligation of these plasmids to pBR322. Although the affinity of the enzyme for heterologous DNA was .apprx. 1/3 of that for pBR322, it was possible to localize preferred binding sites on pTF62 and pTT8. Six binding sites were identified in pTT8, mapping close to 7, 28, 47, 61, 65 and 81 map units (1 unit = 1% of the length of the DNA). Seven such regions located at 3, 27, 48, 60, 67, 81 and 86 map units were found in pTF62. RNA polymerase binding sites found in pBR322 coincided with promoters identified previously by EM analysis of transcriptional complexes prepared in vitro. Evidently, E. coli RNA polymerase binds preferentially to specific sequences in plasmids from thermophilic bacteria, suggesting possible promoter locations in these plasmids.
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    METABOLISM OF CHLORINATED GUAIACOLS BY A GUAIACOL-DEGRADING ACINETOBACTER-JUNII STRAIN
    (1993) GONZALEZ, B; ACEVEDO, C; BREZNY, R; JOYCE, T
    The metabolism of chlorinated guaiacols by a pure bacterial strain identified by its ability to use guaiacol as the sole carbon and energy source was studied. This strain, identified as Acinetobacter junii 5ga, was unable to grow on several chlorinated guaiacols and catechols. However, strain 5ga grown on guaiacol degraded 4- and 5-chloroguaiacol and 4,5-dichloroguaiacol. Under the same conditions, these cells did not degrade 6-chloroguaiacol, 4,6-dichloroguaiacol, 4,5,6-trichloroguaiacol, or tetrachlorognuiacol, suggesting that the substitution at the 6 position in the ring prevents metabolism of the compound. Degradation of 4-chloroguaiacol was dependent on the initial ratio between the chlorinated compound and viable cells. Transient formation of chlorocatechols resulting from incubation of cells with 4-chloroguaiacol or 4,5-dichloroguaiacol was suggested by UV spectroscopy. Gas chromatography analyses of samples from cultures of strain 5ga grown on guaiacol and incubated with 4- and 4,5-dichloroguaiacol confirmed the presence of 4-chlorocatechol and 4,5-dichlorocatechol, respectively. The formation of the latter was corroborated by gas chromatography-mass spectrometry. Thus, this strain is able to initiate metabolism of specific chlorinated guaiacols by O-demethylation. The starting chlorinated guaiacols and their 0-demethylated metabolites inhibited the growth of A.junii 5ga on guaiacol.
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    METABOLISM OF LIGNIN MODEL COMPOUNDS OF THE ARYLGLYCEROL-BETA-ARYL ETHER TYPE BY PSEUDOMONAS-ACIDOVORANS D3
    (1987) VICUNA, R; GONZALEZ, B; MOZUCH, MD; KIRK, TK
    A natural bacterial isolate that we have classified as Pseudomonas acidovorans grows on the lignin model compounds 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (compound 1) and 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (compound 1''), as well as on the corresponding 1-oxo compounds (2 and 2'') as sole sources of carbon and energy. Metabolic intermediates present in cultures growing on compound 1 included compound 2,2-methoxyphenol (guaiacol [compound 3]), .beta.-hydroxypropioveratrone (compound 4), acetoveratrone (compound 5), and veratric acid (compound 6). Also identified were compounds 1'', 2'', .beta.-hydroxypropiovanillone (compound 4''), and acetovanillone (compound 5''), indicating that 4-O demethylation also occurs. The phenolic intermediates were the same as those found in cultures growing on compound 1''. Compounds 2 and 2'' were in part also reduced to compounds 1 and 1'', respectively. Compound 3 was shown to be derived from the 2-methoxyphenoxy moiety. A suggested degradation scheme is as follows: compound 1 .fwdarw. 2 .fwdarw. (3 + 4) .fwdarw. 5 .fwdarw. 6 (and similarly for 1''). In this scheme, the key reaction is cleavage of the ether linkage between C-2 (C.beta.) of the phenylpropane moiety and the 2-methoxyphenoxy moiety in compounds 2 and 2'' (i.e., .beta.-aryl ether cleavage). On the basis of compounds identified, viz., 3 and 4 (4''), cleavage appears formally to be reductive. Because this is unlikely, the initial cleavage products probably were not detected. The implications of these results for the enzyme(s) responsible are discussed.
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    METABOLISM OF MONOCHLORINATED AND DICHLORINATED GUAIACOLS BY RHODOCOCCUS RUBER CA16
    (1995) ACEVEDO, C; BREZNY, R; JOYCE, TW; GONZALEZ, B
    The metabolism of chloroguaiacols by a soil bacterium was studied. The strain was isolated by enrichment, with guaiacol as the sole carbon and energy source, and identified as a Rhodococcus ruber CA16. None of seven chlorinated guaiacols supported bacterial growth. However, ultraviolet spectroscopy, chloride release, and oxygen consumption showed that resting cells grown on guaiacol degraded completely 4-chloroguaiacol, 5-chloroguaiacol, and 6-chloroguaiacol and, to a lesser extent, 4,5-dichloroguaiacol. Gas chromatographic analysis suggested microbial formation of 4-chlorocatechol and 4,5-dichlorocatechol from 4-chloroguaiacol and 4,5-dichloroguaiacol, respectively. Although mono- and dichloroguaiacols did not affect the strain's ability to grow on guaiacol, chlorocatechols completely arrested growth. The role of chlorocatechols in chloroguaiacol metabolism by this guaiacol-degrading bacterial strain is discussed.
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    MONITORING BACTERIAL CONSUMPTION OF LOW-MOLECULAR-WEIGHT LIGNIN DERIVATIVES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY
    (1986) GOYCOOLEA, M; SEELENFREUND, D; RUTTIMANN, C; GONZALEZ, B; VICUNA, R
    The lignolytic capacity of some natural bacterial isolates was examined. Strains were selected from samples of decaying wood by growth in a minimal medium containing aromatic compounds with a structural relationship to lignin as the sole carbon sources. These included derivatives of benzoic and phenylpropanoic acids, as well as a mixture of low molecular weight compounds obtained by fractionation of kraft lignin. Reversed-phase high-performance liquid chromatography analyses before and after cell growth in the latter revealed a degradation pattern of the different compounds present in the culture which was characteristic for each of the strains studied.
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    SERUM IGA DEFICIENCY INDUCED BY PROLONGED PHENYTOIN-TREATMENT
    (1989) TALESNIK, E; RIVERO, SJ; GONZALEZ, B