Página 17 dos resultados de 3028 itens digitais encontrados em 0.004 segundos

Alkaline phosphatase of Blastocladiella emersonii: partial purification and characterization.

Selitrennikoff, C P; Sonneborn, D R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1977 EN
Relevância na Pesquisa
16.55107%
Alkaline phosphomonoesterase (EC 3.1.3.1) activity from Blastocladiella emersonii, while displaying typically broad substrate specificity for phosphorylated organic compounds, exhibited nearly complete substrate preference for N-acetylglucosamine-6-phosphate over N-acetylglucosamine-1-phosphate. Enzyme in zoospore extracts was purified 43-fold by differential centrifugation followed by gel filtration (Sephadex G-200) and then by ion-exchange chromatography (diethylaminoethyl-cellulose). The partially purified enzyme displayed an apparent molecular weight (Sephadex G-200) of approximately 170,000. The activity of partially purified enzyme exhibited a pH optimum of pH 8.5, did not require a metal divalent cation, but was inhibitable by ethylenediaminetetraacetic acid. During the life cycle of the organism, the specific activity of the phosphatase decreased slightly during germination and early exponential growth but then increased about 4.5-fold during sporulation. B. emersonii alkaline phosphatase does not appear to be a repressible enzyme.

Production, purification, and characterization of an extracellular chitosanase from Streptomyces.

Price, J S; Storck, R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1975 EN
Relevância na Pesquisa
16.55107%
The synthesis by Streptomyces sp. no. 6 of an extracellular chitosanase was induced by glucosamine. The enzyme was purified to homogeneity by Sephadex G-100, carboxymethyl-cellulose, and diethylaminoethyl-cellulose chromatography. The purified enzyme hydrolyzed chitosan (the beta-1,4-linked polymer of glucosamine) but not chitin nor carboxymethyl-cellulose. The only products of the hydrolysis detectable by paper chromatography were di- and triglucosamine. Sephadex G-100 chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the molecular weight of the enzyme was between 29,000 and 26,000. Acid hydrolysates of the enzyme contained no cysteic acid or glucosamine or other carbohydrate. At 25 C, maximum activity was obtained between pH 4.5 and 6.5. The enzymatic hydrolysis of chitosan occurred over a wide range of temperatures and was maximal at 60 C. The rate of the reaction was inhibited by concentrations of soluble chitosan higher than 0.5 g/liter. The apparent Km calculated from a Lineweaver-Burke plot was 0.688 g/liter at pH 5.5. The enzyme prevented spore germination and caused a significant decrease in the turbidity of germinated spore suspensions of the Mucor strains tested. Such a decrease was the result of a partial lysis of the cell wall.

Partial Purification and Characterization of a Polysaccharide Depolymerase Associated with Phage-Infected Erwinia amylovora

Vandenbergh, Peter A.; Wright, Ann M.; Vidaver, Anne K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1985 EN
Relevância na Pesquisa
16.55107%
Erwinia amylovora infected with bacteriophage ERA103 produced an enzyme which degraded the extracellular polysaccharide of noninfected cells. The depolymerase enzyme was purified 15-fold by a procedure which included ammonium sulfate precipitation, ultracentrifugation, CM-Sephadex batchwise separation, Sephadex G-50 column chromatography, and Sephacryl S-200 column chromatography. The enzyme had a molecular weight of approximately 21,000 and a pH optimum of 6.0. Activity was enhanced by supplements of 2-mercaptoethanol or dithiothreitol.

Neuraminidase in Bacteroides fragilis.

Berg, J O; Lindqvist, L; Andersson, G; Nord, C E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1983 EN
Relevância na Pesquisa
16.55107%
A neuraminidase from Bacteroides fragilis was purified 542-fold by isoelectric focusing, adsorption chromatography on Affi-Gel 202, and gel filtration chromatography on Sephadex G-200. On isoelectric focusing the neuraminidase was resolved into three differently charged fractions with pI values of 6.8, 7.1, and 7.4. The major component of pI 7.1 was used for further purification. The purified enzyme had optimal activity at pH 6.4 with N-acetylneuraminlactose as the substrate. Its molecular weight, determined by Sephadex G-200 gel filtration chromatography, was 92,000. The neuraminidase hydrolyzed terminal neuraminic acid residues from N-acetylneuraminlactose, fetuin, bovine submaxillary mucin, and porcine stomach lining mucin. A new method for the detection of neuraminidase activity is described which is based on rocket affinoelectrophoresis. It utilizes the differences in the interaction of sialylated and desialylated mucin with Helix pomatia lectin, enzymatic activity being detected by formation of affinorockets after incubation of the neuraminidase with bovine submaxillary mucin.

Partial Purification and Characterization of Hemolysin from a Psychrotrophic Kanagawa-Positive Marine Vibrio †

Peters, Susan; Baross, John A.; Morita, Richard Y.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1982 EN
Relevância na Pesquisa
16.55107%
Psychrotrophic Kanagawa-positive marine vibrios were isolated from soft-shelled clams (Mya arenaria) collected in Yaquina Bay, Oreg. The 235 vibrio isolates obtained were screened for Gram reaction and morphology, Kanagawa reaction on Wagastsuma agar, and response to selected biochemical tests. The vibrio selected for further study was grown in broth, and the hemolysin was precipitated from a cleared supernatant with solid ammonium sulfate. The hemolytic substance was partially purified by DEAE-cellulose and Sephadex G-100 column chromatography. The hemolysin contained protein essential for activity, was thermolabile, and was more active against rabbit erythrocytes at 37°C than at lower temperatures. The molecular weight was estimated at 55,000 by using a Sephadex G-100 column. Hemolytic activity was partially inactivated by gangliosides and lowered against horse erythrocytes. The hemolysin did not react with antibody prepared against vibriolysin from Vibrio parahaemolyticus WP-1 by the Ouchterlony method. The hemolysin was high in aspartic and glutamic acids and low in arginine and histidine. Electrophoresis on a sodium dodecyl sulfate-polyacrylamide gel gave three major bands. The hemolysin from a psychrotrophic vibrio and the hemolytic exotoxin of V. parahaemolyticus had some similar and dissimilar characteristics. The possibility that a Vibrio sp. other than V. parahaemolyticus might serve as the reservoir for the Kanagawa phenotype is discussed.

Preferential binding of radiolabeled zearalenone to a protein fraction of Fusarium roseum graminearum.

Inaba, T; Mirocha, C J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1979 EN
Relevância na Pesquisa
16.55107%
Zearalenone [6-(10-hydroxy-6-oxo-trans-1-undecenyl)beta-resorcyclic acid lactone] is a hormone produced by Fusarium spp. which regulates the sexual stage in F. roseum. 3H- and 14C-labeled zearalenone were found to bind preferentially to one of two peaks containing uncharacterized proteins obtained from the cytosol of young mycelium and resolved by gel column chromatography. The proteins were partially purified by successive resolution on Sephadex G-100, Sephadex G-200, and BioGel P-300. Free zearalenone (37%) was reisolated from the purified proteins after resolution by thin-layer chromatography or partitioning with ethyl acetate.

Cadmium-binding component in Escherichia coli during accommodation to low levels of this ion.

Khazaeli, M B; Mitra, R S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1981 EN
Relevância na Pesquisa
16.55107%
An inducible cadmium-binding protein was isolated from Escherichia coli cells accommodated to 3 X 10(-6) M Cd2+ but not from normal or unaccommodated cells. Sephadex G-100, metal chelate affinity chromatography, and disc gel electrophoresis were used in the purification procedure. The molecular weight of the Cd2+-binding protein was estimated to be about 39,000 by Sephadex G-100 chromatography, making it different from the conventional, much smaller metallothionein.

Isolation of Alkaline and Neutral Proteases from Aspergillus flavus var. columnaris, a Soy Sauce Koji Mold

Impoolsup, Attawut; Bhumiratana, Amaret; Flegel, Timothy W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1981 EN
Relevância na Pesquisa
16.55107%
Two different extracellular proteases, protease I (P-I), an alkaline protease, and protease II (P-II) a neutral protease, from Aspergillus flavus var. columnaris were partially purified by using (NH4)2SO4 precipitation, diethylaminoethyl-Sephadex A-50 chromatography, carboxymethylcellulose CM-52 chromatography, and Sephadex G-100 gel filtration. The degree of purity was followed using polyacrylamide gel electrophoresis. The activity of P-I was completely inhibited by 0.1 mM phenylmethylsulfonyl fluoride, and that of P-II was completely inhibited by 1 mM ethylenediaminetetraacetate. By using these inhibitors with extracts of wheat bran koji, the proportions of total activity that could be assigned to P-I and P-II were 80 and 20%, respectively. This compared favorably with activities estimated by using polyacrylamide gel electrophoresis slices (82 and 18%, respectively). Extracts from factory-run soybean koji gave comparable results. Both enzymes demonstrated maximum activity at 50 to 55°C and only small changes in activity between pH 6 and 11. For P-I, activity was somewhat higher from pH 8.0 to 11.0, whereas for P-II it was somewhat higher from pH 6 to 9. In the presence of 18% NaCl, the activities of both P-I and P-II dropped by approximately 90 and 85%...

Wet and dry bacterial spore densities determined by buoyant sedimentation.

Tisa, L S; Koshikawa, T; Gerhardt, P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1982 EN
Relevância na Pesquisa
16.55107%
The wet densities of various types of dormant bacterial spores and reference particles were determined by centrifugal buoyant sedimentation in density gradient solutions of three commercial media of high chemical density. With Metrizamide or Renografin, the wet density values for the spores and permeable Sephadex beads were higher than those obtained by a reference direct mass method, and some spore populations were separated into several density bands. With Percoll, all of the wet density values were about the same as those obtained by the direct mass method, and only single density bands resulted. The differences were due to the partial permeation of Metrizamide and Renografin, but not Percoll, into the spores and the permeable Sephadex beads. Consequently, the wet density of the entire spore was accurately represented only by the values obtained with the Percoll gradient and the direct mass method. The dry densities of the spores and particles were determined by gravity buoyant sedimentation in a gradient of two organic solvents, one of high and the other of low chemical density. All of the dry density values obtained by this method were about the same as those obtained by the direct mass method.

Genetic and Biochemical Studies on Cell-Bound α-Amylase in Bacillus subtilis Marburg

Nagata, Yoshiho; Yamaguchi, Kazuo; Maruo, Bunji
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1974 EN
Relevância na Pesquisa
16.55107%
A small but significant amount of α-amylase activity was detected in the cells of Bacillus subtilis Marburg. The cell-associated activity was almost constant regardless of the level of extracellular α-amylase activity. The cell-bound amylase activity could be separated into three components, upon Sephadex G-75 chromatography, referred to as components A, B, and C. Component C showed the same properties as the extracellular α-amylases so far examined. Component A had a molecular weight greater than 70,000, as judged from the elution position on Sephadex G-75, and became smaller upon treatment with trypsin but was still larger than that of component C. An α-amylase mutant that lacked extracellular α-amylase completely because of a mutation within the structural gene of the enzyme was found to lose all three cell-bound amylase components simultaneously. These data suggest strongly that the cell-bound amylase components are precursors of the extracellular α-amylase and that the α-amylase of this organism is produced under the direction of the same gene whether the enzyme is within or outside the cell.

Production of molybdenum-coordinating compound by Bacillus thuringiensis.

Ketchum, P A; Owens, M S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1975 EN
Relevância na Pesquisa
16.55107%
Bacillus thuringiensis (ATCC 10792) produces a molybdenum reactive compound (given the trivial name chelin) during growth on iron-deficient medium. This compound accumulates in the culture medium in direct relation to the amount of L-arginine added and reaches a maximum concentration 24 to 48 h after the stationary phase of growth. Chelin absorbs light in the ultraviolet region with absorption maxima at 315 and 248 nm and minima at 284 and 240 nm. Chelin reacts with Na2MoO4, but not with Mo2O4(H2O)6-2+, to form a bright yellow molybdo-chelin complex which absorbs light with an absorption maximum at 330 nm, a minimum at 288 nm, and shoulders at 255 and 400 nm. The differential absorption of molybdo-chelin versus chelin at 425 nm can be used to quantify chelin. This differential absorbance is linear with increasing concentrations of Na2MoO4 and was used to calculate the molar extinction coefficient of molybdochelin at 425 nm (epsilon similar to 6,200). Chelin binds MoO4-2 minus to form a complex (molybdochelin) which migrates as a single band and elutes as a single peak, during acrylamide gel electrophoresis and Sephadex G-15 gel filtration. Molecular weight determinations using Sephadex G-15 gel filtration resulted in an estimated molecular weight of 550 for chelin and an estimated molecular weight of 760 for molybdo-chelin. The peptide nature of chelin is indicated by its positive ninhydrin reaction on thin-layer chromatography plates and by the presence of amino acids in acid-hydrolyzed samples. The major amino acid residues detected were threonine...

Regulation of Two Aspartokinases in Bacillus subtilis

Hampton, Michael L.; McCormick, Neil G.; Behforouz, Nancy C.; Freese, Ernst
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1971 EN
Relevância na Pesquisa
16.55107%
When grown on minimal glucose medium, transformable Bacillus subtilis strains contained two distinct aspartokinases (ATP:l-aspartate 4-phosphotransferase, EC 2.7.2.4). One of these enzymes was inhibited by l-lysine (Lys), whereas the other was insensitive to inhibition but was activated by l-leucine. None of the other amino acids tested had any effect, and the addition of l-threonine did not enhance the inhibition by Lys, in contrast to the concerted inhibition observed for other bacilli. At the end of exponential growth, the Lys-sensitive aspartokinase activity decreased, whereas the Lys-insensitive activity remained relatively constant throughout the stationary phase. The two activities were separated by (NH4)2SO4 fractionation and Sephadex G-200 chromatography. Growth in the presence of Lys reduced the specific activity of aspartokinase by about 50% and eliminated the inhibition by Lys. In extracts of these cells, only Lys-insensitive activity was found upon (NH4)2SO4 fractionation and Sephadex G-200 chromatography. Lys apparently repressed the synthesis of the Lys-sensitive enzyme.

Purification and Characterization of Colicin D

Timmis, K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1972 EN
Relevância na Pesquisa
16.55107%
Colicin D-CA23, obtained by sonic treatment of mitomycin C-induced cells of Escherichia coli K-12 W1485 (colD), was purified by ammonium sulfate precipitation, gel filtration on Sephadex G200, ion-exchange chromatography on diethylaminoethyl cellulose, and isoelectrofocusing. Polyacrylamide-gel electrophoresis, sedimentation velocity analysis, and antigenic analysis indicated that the preparation was homogeneous. Colicin D is composed entirely of amino acids and hence is a simple protein uncomplexed with lipid or lipopolysaccharide. It contains six residues of cysteine per molecule. The molecular weight of colicin D is approximately 92,000, as determined by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis and gel filtration on Sephadex G200. Its sedimentation coefficient is 4.41S. The behavior of colicin D in solutions of sodium dodecyl sulfate and 2-mercaptoethanol indicates that it does not consist of subunits and exists as a single polypeptide chain. Its high molecular weight and presence of six cysteine residues per molecule distinguish colicin D from all colicins previously described. Although colicins D and E3 have similar modes of action, their gross molecular properties are entirely different.

Purification and Partial Characterization of a Bacteriocin from Serratia marcescens

Foulds, John
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1972 EN
Relevância na Pesquisa
16.55107%
Bacteriocin JF246 has been purified from mitomycin C-induced Serratia marcescens cells by salt extraction, ammonium sulfate fractionation, and chromatography on QAE-Sephadex and SP-Sephadex. The purified material is homogeneous on polyacrylamide gel electrophoresis in the presence of 2% sodium dodecyl sulfate or 6 m urea. In the absence of these agents, the bacteriocin associates into aggregates which can be dissociated with 0.4 m NaCl. The bacteriocin is probably composed of a single subunit with a molecular weight of 64,000 daltons. Analytical studies show the bacteriocin to be essentially protein in nature containing less than one residue of glucose or phosphorus per 64,000 daltons.

Purification and Some Properties of Two Boticins

Ellison, Jane S.; Kautter, Judith A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1970 EN
Relevância na Pesquisa
16.55107%
Two bacteriocins (boticins) were elaborated without induction by strain S5, a nontoxigenic variant of Clostridium botulinum type E. After separation of the two active entities by gel filtration on Sephadex G-50, a large particle with boticin activity was isolated by density gradient ultracentrifugation, and a small soluble boticin was purified by continuous curtain electrophoresis and chromatography on sulfoethyl-Sephadex. Large and small boticins were purified 200- and 3,000-fold, respectively, with yields of 50% or more. The small boticin, a basic substance with molecular weight under 30,000, was the predominant species; the large boticin, a negatively charged particle with particle weight greater than 40 × 106, represented less than 20% of the total activity. Both purified boticins were resistant to heat and were attacked by proteolytic enzymes, but the large boticin was less thermostable and less sensitive to proteolytic enzymes than was the smaller variety. The activity of the large boticin was not reduced by treatment with urea or deoxyribonuclease. Both boticins exhibited sporostatic and bactericidal activities for C. botulinum type E, strain 070. A suspension of type E strain 070 vegetative cells was rendered nonviable within 9 min by the small boticin. The lethal action of this bacteriocin was not reversed by trypsin.

Antigens of Neisseria gonorrhoeae: Characterization by Gel Filtration, Complement Fixation, and Agar-Gel Diffusion of Antigens of Gonococcal Protoplasm

Danielsson, Dan G.; Schmale, John D.; Peacock, William L.; Thayer, James D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1969 EN
Relevância na Pesquisa
16.55107%
With the use of the agar-gel-diffusion and complement-fixation techniques, it was shown that protoplasm from different gonococcal isolates reacted with sera from some humans with a history of gonorrhea but did not react with “normal” human sera. The reactive antigen(s) could be partially separated from the other antigens by passing the gonococcal protoplasm through Sephadex G-200. The antigen(s) reacting in the gel-diffusion and complement-fixation tests appeared in the same fraction. On the basis of Sephadex gel filtration, the molecular weight of this antigen(s) is probably greater than 200,000.

Purification and Characterization of β-Glucosidase of Alcaligenes faecalis1

Han, Y. W.; Srinivasan, V. R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1969 EN
Relevância na Pesquisa
16.55107%
A cellobiose-utilizing bacterium isolated from sugar cane bagasse and identified as a strain of Alcaligenes faecalis (ATCC 21400) produced an inducible β-glucoside-splitting enzyme. The enzyme was purified by a series of streptomycin and ammonium sulfate fractionations and by Sephadex and diethylaminoethyl column chromatography. The final preparation was purified 130-fold, with a recovery of about 10% of the initial enzyme activity. The enzyme had a wide pH range, with optimal activity at pH 6.0 to 7.0. The enzyme was stable in solution at pH 6.5 to 7.8 when kept at 30 C for 2 hr, but it was destroyed by temperatures above 55 C. At 58 and 60 C, the time required to inactivate 90% of the initial activity was 16 and 6.5 min, respectively. An activation energy of 9,500 cal/mole and a Km of 1.25 × 10−4m were obtained by using p-nitrophenyl β-glucoside as a substrate. The Ki value and hydrolysis of cellobiose by the enzyme indicated a high affinity of the enzyme for the cellobiose. The enzyme had its specificity on β-glucosidic linkage and the rate of hydrolisis of glucosides depended upon the nature of the aglycon moiety. The inactivation studies showed the presence of sulfhydryl groups in the enzyme. The activity of the enzyme was easily destroyed by the Cu++ and Hg++ ions. The Michaelis-Menton relationship and the rate of heat inactivation indicated the presence of one type of noninteracting active site in the bacterial β-glucosidase. Molecular weight of the enzyme was estimated by gel filtration (Sephadex G-200) and sucrose density gradient...

Resistance of Escherichia coli to Penicillins VII. Purification and Characterization of a Penicillinase Mediated by the R Factor R1

Lindqvist, R. Christer; Nordström, Kurt
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1970 EN
Relevância na Pesquisa
16.55107%
The penicillinase mediated by the R factor R1 in Escherichia coli has been purified and characterized. The purification procedure contained the following three steps: spheroplast formation, chromatography of the spheroplast supernatant fluid on DEAE cellulose, and preparative polyacrylamide-gel electrophoresis. The protein obtained gave only one band in analytical polyacrylamide-gel electrophoresis. To obtain milligram quantities of the enzyme, gel filtration on Sephadex G75 was run before the last step in the purification. By gel filtration on Sephadex G75, the molecular weight was estimated as 22,000. The pH optimum, tested in universal buffer, was 7.0. The turnover numbers for benzylpenicillin, d-ampicillin, and 6-aminopenicillanic acid were 4.2 × 104, 6.3 × 104, and 2.2 × 104 moles of substrate hydrolyzed per min by 1 mole of enzyme, whereas the Michaelis constants were 100, 160, and 440 μm, respectively. Cephalosporins were much poorer substrates for the R1 penicillinase than were the penicillins. The turnover number for cephalosporin C, cephaloridine, and 7-amino-cephalosporanic acid were 2.4 × 103, 5 × 102, and less than 2 × 102, respectively. These properties show that the R1 penicillinase is quite different from the chromosomally mediated penicillinase of E. coli (11). However...

Specialized Subregions of the Bifunctional hisB Gene of Salmonella typhimurium

Houston, L. L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1973 EN
Relevância na Pesquisa
16.55107%
Forty-three hisB mutants of Salmonella typhimurium have been screened to determine the molecular size of the resulting histidinol phosphate phosphatase activity, one of the activities of a bifunctional enzyme produced by this gene which also controls imidazole glycerol phosphate dehydrase activity. Mutation in hisB can lead to the loss of both phosphatase and dehydrase activities, or only of dehydrase activity. Through the use of nonsense mutants lacking dehydrase activity, a distinct point of transition was detected near the middle of hisB at which a dramatic change occurs in the size of the phosphatase enzyme that is synthesized. A missense mutant with a lesion in this region has a high-molecular-weight enzyme which is eluted in the void volume of a Sephadex G-200 column. The enzyme from nonsense mutants near the transition point have molecular weights near 40,000. Even though the buffer conditions are designed to favor the stabilization of the high-molecular-weight form, some mutants have both high- and low-molecular-weight forms. The polypeptide chain specified by the operator proximal part of hisB is sufficient to allow the expression of phosphatase activity. The synthesis of substantially less than the complete product of hisB resulted in association into a form similar to the native enzyme which was found in the void volume of a Sephadex G-200 column.

Purification and Genetic Determination of Bacteriocin Production in Enterobacter cloacae

de Graaf, F. K.; Tieze, G. A.; Bonga, Sj. Wendelaar; Stouthamer, A. H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1968 EN
Relevância na Pesquisa
16.55107%
Enterobacter cloacae (strain DF13) was found to produce a bacteriocin which could be induced by mitomycin C. In the supernatant fluid of the induced culture phagelike particles were found. The bacteriocin was partially purified from induced cultures by ammonium sulfate precipitation and gel-filtration on Sephadex G-150. Ultraviolet-absorbing material was eluted from the Sephadex column in three fractions. The biological activity was mainly present in the second fraction and is associated with a protein with a molecular weight of about 61,000. The phagelike particles were found in the first fraction and show no biological activity. Upon conjugation of E. cloacae strain DF13 with another strain of the same species and with Escherichia coli K-12S, the ability to produce bacteriocin was transferred. The new bacteriocinogenic strain produced bacteriocin, which could not be distinguished from that produced by E. cloacae strain DF13. Although transfer of the bacteriocinogenic factor often occurred together with transfer of the ability to produce phagelike particles, it was shown that these two factors are two separate genetic entities. In addition to a bacteriocinogenic factor, E. cloacae strain DF13 was found to carry two other transferable plasmids: one determining resistance against streptomycin and sulfanilamide and another determining resistance against penicillin.