Characterization of melanin produced by a wild-type strain of Bacillus cereus

ABSTRACT The predicted amino acid sequence of Bacillus subtilis ycbQ (renamed cwlJ) exhibits high similarity to those of the deduced C-terminal catalytic domain of SleBs, the specific cortex-hydrolyzing enzyme of B. cereus and the deduced one of B. subtilis. We constructed acwlJ::lacZ fusion in the B. subtilischromosome. The β-galactosidase activity and results of Northern hybridization and primer extension analyses of the cwlJgene indicated that it is transcribed by EςE RNA polymerase. cwlJ-deficient spores responded to bothl-alanine and AGFK, the A 580 values of spore suspensions decreased more slowly than in the case of the wild-type strain, and the mutant spores released less dipicolinic acid than did those of the wild-type strain during germination. However, the mutant spores released only slightly less hexosamine than did the wild-type spores. In contrast, B. subtilis sleB spores did not release hexosamine at a significant level. While cwlJand sleB spores were able to germinate, CJSB (cwlJ sleB) spores could not germinate but exhibited initial germination reactions, e.g., partial decrease inA 580 and slow release of dipicolinic acid. CJSB spores became slightly gray after 6 h in the germinant, but their refractility was much greater than that of sleB mutant spores. The roles of the sleB and cwlJmutations in germination and spore maturation are also discussed.

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Characterization of melanin produced by a wild-type strain of Bacillus thuringiensis

The Journal of General and Applied Microbiology ◽

10.2323/jgam.50.183 ◽

2004 ◽

Vol 50 (4) ◽

pp. 183-188 ◽

Cited By ~ 23

Author(s):

Yuehua Chen ◽

Yinyue Deng ◽

Jinhong Wang ◽

Jun Cai ◽

Gaixin Ren

Keyword(s):

Bacillus Thuringiensis ◽

Type Strain ◽

Wild Type Strain ◽

Wild Type

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Purification and characterization of a β-glucosidase from Streptomyces lividans 66

Canadian Journal of Microbiology ◽

10.1139/m90-009 ◽

1990 ◽

Vol 36 (1) ◽

pp. 53-56 ◽

Cited By ~ 18

Author(s):

Anca Mihoc ◽

Dieter Kluepfel

Keyword(s):

High Performance Liquid Chromatography ◽

Molecular Sieve ◽

Type Strain ◽

High Performance ◽

Wild Type Strain ◽

Streptomyces Lividans ◽

Wild Type ◽

Purification And Characterization ◽

Anion Exchange Column

An intracellular β-1, 4-D-glucosidase (EC 3.2.1.21) was isolated from the mutant strain HP-3 of Streptomyces lividans 66 which produced about 12 times more enzyme than the wild-type strain. The purification was carried out by anion exchange column chromatography followed by high-performance liquid chromatography on DEAE and on molecular sieve columns. The enzyme is glycosylated and has an apparent Mr of 51 000 and a pI of 4.3. Its activity was optimal at pH 6.5 and at a temperature of 40 °C. The Km and the Vmax on cellobiose were 3.1 mM and 65.6 μmol min−1 mg−1 of enzyme. Key words: β-glucosidase, Streptomyces lividans, purification, characterization.

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The dlt Operon of Bacillus cereus Is Required for Resistance to Cationic Antimicrobial Peptides and for Virulence in Insects

Journal of Bacteriology ◽

10.1128/jb.00892-09 ◽

2009 ◽

Vol 191 (22) ◽

pp. 7063-7073 ◽

Cited By ~ 52

Author(s):

Z. Abi Khattar ◽

A. Rejasse ◽

D. Destoumieux-Garzón ◽

J. M. Escoubas ◽

V. Sanchis ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Bacillus Cereus ◽

Cell Walls ◽

Type Strain ◽

Pathogenic Bacteria ◽

Wild Type Strain ◽

Wild Type ◽

Gram Positive ◽

Cationic Antimicrobial Peptides ◽

Humoral Immune

ABSTRACT The dlt operon encodes proteins that alanylate teichoic acids, the major components of cell walls of gram-positive bacteria. This generates a net positive charge on bacterial cell walls, repulsing positively charged molecules and conferring resistance to animal and human cationic antimicrobial peptides (AMPs) in gram-positive pathogenic bacteria. AMPs damage the bacterial membrane and are the most effective components of the humoral immune response against bacteria. We investigated the role of the dlt operon in insect virulence by inactivating this operon in Bacillus cereus, which is both an opportunistic human pathogen and an insect pathogen. The ΔdltBc mutant displayed several morphological alterations but grew at a rate similar to that for the wild-type strain. This mutant was less resistant to protamine and several bacterial cationic AMPs, such as nisin, polymyxin B, and colistin, in vitro. It was also less resistant to molecules from the insect humoral immune system, lysozyme, and cationic AMP cecropin B from Spodoptera frugiperda. ΔdltBc was as pathogenic as the wild-type strain in oral infections of Galleria mellonella but much less virulent when injected into the hemocoels of G. mellonella and Spodoptera littoralis. We detected the dlt operon in three gram-negative genera: Erwinia (Erwinia carotovora), Bordetella (Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica), and Photorhabdus (the entomopathogenic bacterium Photorhabdus luminescens TT01, the dlt operon of which did not restore cationic AMP resistance in ΔdltBc ). We suggest that the dlt operon protects B. cereus against insect humoral immune mediators, including hemolymph cationic AMPs, and may be critical for the establishment of lethal septicemia in insects and in nosocomial infections in humans.

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Characterization of emeA, anorA Homolog and Multidrug Resistance Efflux Pump, inEnterococcus faecalis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.45.12.3574-3579.2001 ◽

2001 ◽

Vol 45 (12) ◽

pp. 3574-3579 ◽

Cited By ~ 84

Author(s):

Brandie M. Jonas ◽

Barbara E. Murray ◽

George M. Weinstock

Keyword(s):

Drug Resistance ◽

Multidrug Resistance ◽

Type Strain ◽

Deletion Mutant ◽

Wild Type Strain ◽

Efflux Pump ◽

Wild Type ◽

Type Gene ◽

Encoding Genes

ABSTRACT We hypothesized that multidrug resistance efflux pumps (MDRs) may be contributing to the drug resistance of enterococci. We recently identified potential MDR-encoding genes in the Enterococcus faecalis V583 genome. Among the putative MDRs, we found a gene that encodes a NorA homolog and have characterized this enterococcal MDR in the present study. A mutant from which the enterococcal NorA homolog has been deleted has reduced resistance to several NorA substrates. Complementation of the deletion mutant with the wild-type gene verified the involvement of this enterococcal gene in resistance to ethidium bromide (EtBr) and norfloxacin. Known MDR inhibitors (reserpine, lansoprazole, and verapamil) inhibit the efflux of EtBr and norfloxacin in wild-type strain OG1RF. A fluorescence assay with EtBr allowed us to quantitate the efflux capability of the enterococcal NorA pump. On the basis of these results, we have named this enterococcal gene emeA (enterococcal multidrug resistance efflux).

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Characterization of Human Bactericidal Antibodies to Bordetella pertussis

Infection and Immunity ◽

10.1128/iai.67.3.1424-1431.1999 ◽

1999 ◽

Vol 67 (3) ◽

pp. 1424-1431 ◽

Cited By ~ 34

Author(s):

Alison A. Weiss ◽

Paula S. Mobberley ◽

Rachel C. Fernandez ◽

ChrisAnna M. Mink

Keyword(s):

Immune Response ◽

Bactericidal Activity ◽

Bordetella Pertussis ◽

Type Strain ◽

Wild Type Strain ◽

Resistance Mechanism ◽

Wild Type ◽

Occupationally Exposed ◽

Bactericidal Activities

ABSTRACT The Bordetella pertussis BrkA protein protects against the bactericidal activity of complement and antibody; however, some individuals mount an immune response that overcomes this bacterial defense. To further characterize this process, the bactericidal activities of sera from 13 adults with different modes of exposure toB. pertussis (infected as adults, occupational exposure, immunized with an acellular vaccine, or no identified exposure) against a wild-type strain and a BrkA complement-sensitive mutant were evaluated. All of the sera killed the BrkA mutant, suggesting past exposure to B. pertussis or cross-reactive organisms. Several samples had no or minimal activity against the wild type. All of the sera collected from the infected and occupationally exposed individuals but not all of the sera from vaccinated individuals had bactericidal activity against the wild-type strain, suggesting that some types of exposure can induce an immune response that can overcome the BrkA resistance mechanism. Adsorbing serum with the wild-type strain removed the bactericidal antibodies; however, adsorbing the serum with a lipopolysaccharide (LPS) mutant or an avirulent (bvg mutant) strain did not always result in loss of bactericidal activity, suggesting that antibodies to either LPS orbvg-regulated proteins could be bactericidal. All the samples, including those that lacked bactericidal activity, contained antibodies that recognized the LPS of B. pertussis. Bactericidal activity correlated best with the presence of the immunoglobulin G3 (IgG3) antibodies to LPS, the IgG subtype that is most effective at fixing complement.

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Mutagenesis by Insertion of Tn4001 into the Genome of Spiroplasma citri: Characterization of Mutants Affected in Plant Pathogenicity and Transmission to the Plant by the Leafhopper Vector Circulifer haematoceps

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.4.454 ◽

1997 ◽

Vol 10 (4) ◽

pp. 454-461 ◽

Cited By ~ 42

Author(s):

X. Foissac ◽

J. L. Danet ◽

C. Saillard ◽

P. Gaurivaud ◽

F. Laigret ◽

...

Keyword(s):

Type Strain ◽

Culture Medium ◽

Wild Type Strain ◽

Single Copy ◽

Wild Type ◽

Spiroplasma Citri ◽

Leafhopper Vector ◽

Circulifer Haematoceps ◽

Plant Pathogenicity

Two hundred and fifty-seven transposon Tn4001 mutants of Spiroplasma citri strain GII3 were used for transmission assays by the leafhopper vector Circulifer haematoceps into periwinkle (Catharanthus roseus) plants. Multiplication of the mutants in the two hosts, the leafhopper and the plant, as well as the symptom expression in the plant were studied. Two mutants, GMT 470 and GMT 553, caused no symptoms on plants. Tn4001 is inserted as a single copy in the genome of these mutants. Mutant GMT 470 did not multiply, or multiplied only poorly, in the leaf-hopper and was not transmitted by the insect to the plant, nor to culture medium through Parafilm membrane. The growth rate of GMT 470 in SP4 medium was twice as slow as that of wild-type strain GII3. Mutant GMT 553 multiplied in the leafhopper as well as the wild-type spiro-plasma, and was transmitted by the leafhoppers into the plants, where it reached the same titers as the wild-type strain but in approximately twice as much time. The plants containing high titers of mutant GMT 553 remained symptomless for several weeks. However, symptoms began to develop at a time when revertants that had lost the transposon were detected.

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Enhancement of surfactin production of Bacillus subtilis fmbR by replacement of the native promoter with the Pspac promoter

Canadian Journal of Microbiology ◽

10.1139/w09-044 ◽

2009 ◽

Vol 55 (8) ◽

pp. 1003-1006 ◽

Cited By ~ 22

Author(s):

Huigang Sun ◽

Xiaomei Bie ◽

Fengxia Lu ◽

Yaping Lu ◽

Yundailai Wu ◽

...

Keyword(s):

Bacillus Subtilis ◽

Bacillus Cereus ◽

Type Strain ◽

Wild Type Strain ◽

Inducible Promoter ◽

Type B ◽

Wild Type ◽

Native Promoter ◽

Surfactin Production

Bacillus subtilis fmbR-1 was obtained from wild-type B. subtilis fmbR by replacement of the native promoter of the surfactin operon with the inducible promoter Pspac. The recombinant B. subtilis fmbR-1 produced more antibacterial substances than the wild-type strain. The overproducing phenotype was related to the enhancement of antagonistic activities against Bacillus cereus . HPLC peaks of surfactin for recombinant fmbR-1 showed patterns of lipopeptides similar to those of the wild-type strain, and surfactin production of the recombinant fmbR-1 was up to about fivefold greater than that of the wild-type strain without induction by isopropyl β-d-1-thiogalactopyranoside. However, the production of surfactin increased to about 10-fold more than that of the wild-type strain when it was induced by isopropyl β-d-1-thiogalactopyranoside.

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Lysine-specific gingipain K and heme/hemoglobin receptor HmuR are involved in heme utilization in Porphyromonas gingivalis.

Acta Biochimica Polonica ◽

10.18388/abp.2004_3618 ◽

2004 ◽

Vol 51 (1) ◽

pp. 253-262 ◽

Cited By ~ 16

Author(s):

Waltena Simpson ◽

Teresa Olczak ◽

Caroline A Genco

Keyword(s):

Porphyromonas Gingivalis ◽

Type Strain ◽

Double Mutant ◽

Wild Type Strain ◽

Wild Type ◽

Outer Membrane Receptor ◽

Iron Source ◽

Identification And Characterization

We have previously reported on the identification and characterization of the Porphyromonas gingivalis A7436 strain outer membrane receptor HmuR, which is involved in the acquisition of hemin and hemoglobin. We demonstrated that HmuR interacts with the lysine- (Kgp) and arginine- (HRgpA) specific proteases (gingipains) and that Kgp and HRgpA can bind and degrade hemoglobin. Here, we report on the physiological significance of the HmuR-Kgp complex in heme utilization in P. gingivalis through the construction and characterization of a defined kgp mutant and a hmuR kgp double mutant in P. gingivalis A7436. The P. gingivalis kgp mutant exhibited a decreased ability to bind both hemin and hemoglobin. Growth of this strain with hemoglobin was delayed and its ability to utilize hemin as a sole iron source was diminished as compared to the wild type strain. Inactivation of both the hmuR and kgp genes resulted in further decreased ability of P. gingivalis to bind hemoglobin and hemin, as well as diminished ability to utilize either hemin or hemoglobin as a sole iron source. Collectively, these in vivo results further confirmed that both HmuR and Kgp are involved in the utilization of hemin and hemoglobin in P. gingivalis A7436.

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