Photosensitivity in carotenoidless mutants of Micrococcus luteus (Sarcina lutea): non-photodynamic menaquinone destruction in white light.
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Carotenoids↗
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Isolation and purification of a Campylobacter upsaliensis autolysin.
Autolytic activity in the soluble and sediment fractions of sonicates of the spiral and the coccoid form of Campylobacter upsaliensis could not be demonstrated by native (nondenaturing) polyacrylamide gel electrophoresis (PAGE). Autolysins were detected, however, by using denaturing sodium dodecyl sulfate (SDS)-PAGE gels containing either purified Escherichia coli peptidoglycan or whole cells of Micrococcus luteus (Micrococcus lysodeikticus) as the turbid substrate, with subsequent renaturation by treatment with Triton X-100 buffer. In renaturing gels that contained Escherichia coli peptidoglycan, 14 putative autolytic bands ranging from 200 to 12 kDa were detected. In similar gels containing whole cells of M. luteus, only a single band appeared with a molecular mass of 34 kDa. This band corresponded to one of the bands present in the gels containing Escherichia coli peptidoglycan. This common autolysin was isolated by adsorbing it from Campylobacter upsaliensis soluble fractions onto M. luteus cells and then subjecting these cells to renaturing SDS-PAGE in gels containing Escherichia coli peptidoglycan. The 34-kDa autolysin differed from a single 51-kDa autolysin unique to the M. luteus cells, and when isolated from an SDS-PAGE gel, was pure when tested by isoelectric focusing. The N-terminal amino acid sequence analysis showed the first 15 amino acids of the 34-kDa autolysin to have 67% identity to a part of antigenic protein PEB4 of Campylobacter jejuni. The purified autolysin was used to immunize rabbits and the antibodies produced precipitated autolytic activity from cell lysates. The specificity of the antibodies was shown by Western blotting: only a single specific band occurred, with a molecular mass of 34 kDa, and thus it seems unlikely that the 34-kDa autolysin was derived from any of the other autolysins that were detected.
Amino Acid Sequence↗
Effects of nitric oxide and nitrogen dioxide on bacterial growth.
The effects of low concentrations of nitric oxide (NO) and nitrogen dioxide (NO2) on actively dividing cultures of Staphylococcus aureus, Micrococcus luteus, Micrococcus roseus, Serratia marcescens, Bacillus subtilis, Bacillus circulans, Bacillus megaterium, and Bacillus cereus were studied. Fresh cultures of each organism were incubated for 24 h at 25 degrees C on both nutrient agar and mineral salts glucose agar plates under atmospheres containing various low concentrations of NO in air (0 to 1.9 ppm [0 to 2.0 micrograms/g of air]), NO2 in air (0 to 5.5 ppm [0 to 8.8 micrograms/g of air]), or NO and NO2 in air. Bacteria grown under air only were used as controls. After incubation, the colonies that developed on the plates were counted. None of the bacteria tested was affected by NO or NO2 at the indicated concentrations while growing on nutrient agar. Serratia marcescens, B. circulans, B. subtilis, B. megaterium, and B. cereus grown on mineral salts glucose agar were not significantly affected by NO or NO2. Low concentrations (0 to 1.9 ppm) of NO were bacteriostatic to log-phase cultures of M. roseus, M. luteus, and Staphylococcus aureus grown on mineral salts glucose agar. Bacteriostatic activity over a 24-h interval was maximal at an initial NO concentration of 1 ppm. Appreciable amounts of NO2 were produced in 24 h at initial NO concentrations greater than 1 ppm. These results suggest that NO2 may reduce the bacteriostatic activity of NO. Low concentrations (0 to 5.5 ppm) of NO2 in air did not affect any of the bacteria tested. At these low concentrations, NO affected bacterial growth, although NO2, NO2-, and NO3- did not. In addition, it was determined that the bacteriostatic activity observed in this study was not due to an increase in the acidity of the medium.
Bacillus↗
Essential oil constituents and in vitro antimicrobial activity of Decalepis hamiltonii roots against foodborne pathogens.
Hydrodistillation of Decalepis hamiltonii roots yielded an essential oil (0.33% v/w) that contained 2-hydroxy-4-methoxybenzaldehyde (37.45%), 2-hydroxybenzaldehyde (31.01%), 4-O-methylresorcylaldehyde (9.12%), benzyl alcohol (3.16%), and alpha-atlantone (2.06%) as major constituents, with aromatic aldehydes constituting the main fraction of this root's essential oil. The oil was tested for its antimicrobial activity against foodborne pathogens responsible for food spoilage and human pathologies using standard antimicrobial assays. It exhibited strong antimicrobial activity against Bacillus cereus, Bacillus megaterium, Candida albicans, Escherichia coli, Micrococcus luteus, Micrococcus roseus, and Staphylococcus aureus at a concentration range of 1:0 with inhibitory activities of 27, 23, 16, 19, 22, 19, and 23 mm, respectively, which are comparable to those of the standards. The roots of D. hamiltonii, therefore, may be considered as an inexpensive source of an essential oil rich in antimicrobial compounds against foodborne pathogens.
Anti-Bacterial Agents↗
Characterization and ion channel activities of novel antibacterial proteins from the skin mucosa of carp (Cyprinus carpio).
A detergent-solubilized fraction of skin mucus of carp (Cyprinus carpio) induced ion channels after reconstitution into planar lipid bilayers. A differential extraction using a non-ionic detergent followed by electrophoretic separation led to the isolation of two hydrophobic 31-kDa and 27-kDa proteins. In contrast to the 27-kDa protein, which was glycosylated, the 31-kDa did not bind to concanavalin A. The reconstitution of these proteins into a planar lipid bilayer restored the ionophore behavior already observed with the crude mucus. The main unit conductance levels were about 900 pS for the 27-kDa protein and 500 pS for the 31-kDa protein, and selectivity measurements gave Pcl/Pk ratios of 0.6 and 1.0, respectively. These proteins had large potent microbicidal activities (0.018-0.18 microM) against different strains of gram-negative and gram-positive bacteria. This behavior can be compared with insect defensins that are known to form large ion channels in the bacterial membrane. To exclude the eventuality of bacterial origin, the bacterial flora of the crude mucus were analysed and the following were identified: Pseudomonas cepacia; Micrococcus luteus; Micrococcus roseus; Flavobacterium sp.; Aeromonas hydrophila. Antibacterial assays with both proteins were performed against these specific strains and revealed good growth inhibition activities. Furthermore, microsequencing analysis showed that the 31-kDa protein was protected on its N-terminal extremity in contrast to the 27-kDa protein, which had a 19-amino-acid sequence. This last sequence, when compared with sequences in protein data banks, did not reveal any significant similarities to other proteins. These results suggest that these novel proteins could be involved in antibacterial defense processes in fish.
Amino Acid Sequence↗
Isolation and characterization of microorganisms from instruments used by pedicurists operating within Lagos metropolis, Nigeria.
Eight bacterial and five fungal species were isolated from swab samples taken from instruments used by pedicurists operating at three different sites in Lagos, Nigeria. The bacterial isolates included Micrococcus luteus, Micrococcus roseus, Staphylococcus epidermidis, Staphylococcus aureus, Hafnia spp, Shigella spp, Bacillus subtilis and Bacillus spp. The five fungal isolates were identified as Aspergillus niger, Aspergillus flavus, Mucor spp, Trichophyton spp and Candida albicans. The presence of these microorganisms, some of which are pathogenic, is an indication that pedicurists could be contributing towards the spread of skin and nail infections within the Lagos metropolis.
Bacteria↗
Bacterial decontamination of DUWL biofilm using Oxygenal 6.
The aim of this study was bacteriological assessment of the dental unit waterlines (DUWL) biofilm - concentration and composition of the aerobe and facultative anaerobe bacterial microflora, and evaluation of the influence of a disinfecting product, Oxygenal 6, on the biofilm composition. Tubing fragments were taken from 25 units twice, before and after disinfection, and bacterial suspension of the biofilm was obtained from the samples. The bacterial flora was determined with the plate culture method. Bacteria were identified with biochemical microtests: API 20E, API 20NE (bioMerieux, France) and GP2 MicroPlate(TM) (BIOLOG, USA). Before disinfection, the following bacteria were identified: Gram-negative bacteria - Ralstonia pickettii, Pseudomonas vesicularis, Sphingomonas paucimobilis, Xanthomonas maltophilia; Gram-positive cocci - Micrococcus luteus, Micrococcus lylae, Staphylococcus cohnii, Staphylococcus lentus, Staphylococcus spp., Streptococcus spp.; Actinomycetes - Streptomyces albus. The prevailing bacteria were: Ralstonia pickettii (78.62%), found in all the units, and Sphingomonas paucimobilis (20.45%). After DUWL disinfection, Sphingomonas paucimobilis (88.79%) dominated in the biofilm, Staphylococcus spp. - 5.61% and Pseudomonas spp. - 3.74% were next most frequently occurring bacteria, and in more than a half of the biofilm samples 100% reduction of the bacterial microflora occurred. This study confirms effectiveness of Oxygenal 6 in bacterial decontamination of the DUWL biofilm.
Anti-Bacterial Agents↗
Process of consecutive cell divisions and separations in a regular tetrads-forming mutant of Micrococcus lysodeikticus (luteus).
A mutant MT of Micrococcus lysodeikticus (luteus) IFO 3333, whose minimum growing unit is not a single cell, but a tetrad unlike the wild-type divides by binary fission of each monococcus, and then separates first into two daughter tetrads, second into four tetrads and third into eight tetrads. The three planes of either the cell division or the cell separation are equivalent to one another and oriented at right angles in three dimensions, respectively. The process of consecutive cell divisions and separations of the mutant tetrads was schematically illustrated.
Cell Division↗
Cell wall autolysis in log phase cells of Micrococcus lysodeikticus (luteus).
Log phase cells of Micrococcus lysodeikticus (luteus) IFO 3333 autolyzed when incubated at 37 C in 0.01 M sodium-phosphate buffer pH 7.5. The enzyme involved in the autolysis was recovered mainly in an aqueous phase from cytoplasmic membranes and cytoplasmic materials treated with n-butanol, and proved to be an N-acetylmuramyl-L-alanine amidase. The autolysis of log phase cells suspended in autolyzing buffer was depressed by the addition of trypsin to the buffer.
Agar↗
Cell wall-bridge maintaining three dimensional structure of cell packets formed by the localized suppression of cell separation of a Micrococcus lysodeikticus (luteus) mutant.
Cell packets of Micrococcus lysodeikticus (luteus) mutant strain MT grown in medium supplemented with trypsin consisted of a tetrad as the unit structure. An interstice was observed between the unit-tetrads, and a three dimensional structure of cell packets was maintained by the cell wall-bridge along the rim of the cell packets which linked each unit-tetrad. This unique structure of strain MT cell packets seemed to occur when the cell separation was suppressed locally, i.e., when the cross wall inside the initial site of cell separation was cut off, while the wall outside the initial site of separation was not cut off but remained as a joint of the daughter cells. The mechanism of cell wall-bridge formation is discussed in connection with cell separation.
Amino Acids↗
Association of lack of cell wall teichuronic acid with formation of cell packets of Micrococcus lysodeikticus (luteus) mutants.
Morphological mutants of Micrococcus lysodeikticus (luteus) were isolated by treatment with N-methyl-N'-nitro-N-nitrosoguanidine. They occurred on plates in large, regular cell packets, whereas the parent cells usually grew as groups of two or four cells or as short chains. The mutants required a much higher concentration of Mg2+ for growth than the parent cells. The concentrations of Mg2+ and other components of the culture medium tested did not significantly affect the morphology of either the parent or mutant strains. The mutant strains were not agglutinated by antiserum to M. lysodeikticus, which mainly interacts with teichuronic acid on the cell surface, and chemical analysis of isolated cell walls of the mutants indicated the absence of teichuronic aicd. No significant differences were detected between the parent and mutant strains in the amounts of other cell wall components, e.g., peptidoglycan, protein, and teichoic acid. They possible roles of teichuronic acid in cell separation and attachment of divalent cations are discussed.
Acetylgalactosamine↗
Secondary structure and phylogeny of Staphylococcus and Micrococcus 5S rRNAs.
Nucleotide sequences of 5S rRNAs from four bacteria, Staphylococcus aureus Smith (diffuse), Staphylococcus epidermidis ATCC 14990, Micrococcus luteus ATCC 9341 and Micrococcus luteus ATCC 4698, were determined. The secondary structural models of S. aureus and S. epidermidis sequences showed characteristics of the gram-positive bacterial 5S rRNA (116-N type [H. Hori and S. Osawa, Proc. Natl. Acad. Sci. U.S.A. 76:381-385, 1979]). Those of M. luteus ATCC 9341 and M. luteus ATCC 4698 together with that of Streptomyces griseus (A. Simoncsits, Nucleic Acids Res. 8:4111-4124, 1980) showed intermediary characteristics between the gram-positive and gram-negative (120-N type [H. Hori and S. Osawa, 1979]) 5S rRNAs. This and previous studies revealed that there exist at least three major groups of eubacteria having distinct 5S rRNA and belonging to different stems in the 5S rRNA phylogenic tree.
Base Sequence↗
Characterization of Micrococcus antarcticus sp. nov., a psychrophilic bacterium from Antarctica.
A Gram-positive, cold-adapted, aerobic, spherical actinobacterium (strain T2T) with a quite low cardinal growth temperature was isolated from Chinese Great-Wall station in Antarctica. Sequence comparisons of the 16S rDNA indicated the isolate to be a phylogenetic member of the genus Micrococcus, family Micrococcaceae, in which it represents a novel lineage. The phylogenetic distinctness of the isolate with respect to the type strains Micrococcus luteus and Micrococcus lylae was supported by DNA-DNA similarity values of less than 40%. Chemotaxonomic properties supported the placement of the isolate in the genus Micrococcus. The diagnostic diamino acid of the cell-wall peptidoglycan is lysine. The predominant menaquinones are MK-8 and MK-8(H2). The G + C content of the DNA of the isolate is 66.4 mol%. Genotypic, morphological and physiological characteristics were used to describe a new species of Micrococcus, for which the name Micrococcus antarcticus is proposed. The type strain is T2T (= AS 1.2372T).
Amino Acids↗
[Microorganisms of the fam. Micrococcaceae in the production and storage of prepackaged veal].
Studies were carried out on the numbers and composition of organisms belonging to family Micrococcaceae in the production and storing of calf meat on a dressing combine supplied with modern equipment. Investigated were a total of 60 samples taken from small cuts of veal of the various carcass parts. The samples were packed either under vacuum or without such, and were studied immediately after cutting in small parts or after storing for 48 and 72 hours at 4 to 6 degrees C. It was found that the amount of Micrococcaceae organisms on the surface of cut meat packed out or in vacuum was within the range of 10(3) up to 10(4)/g, and it was shown to be in close relation to the microbial contamination of the initial raw material. There was no rise of the numbers of micrococci and staphylococci of veal that was cut and packed out of vacuum and kept for 48 hours at 4 to 6 degrees C. At refrigerator storing of veal that was packed under vacuum there was no increase in the microbial numbers at the 72nd hour. This pointed to the advantage of using the introduced technology of packing the meat under vacuum. Micrococcus luteus (56.7%), Micrococcus varians (41.8%), and Staphylococcus saprophyticus (1.5%) were isolated from cuts of veal packed both in and out of vacuum. No pathogenic staphylococci were found.
Animals↗
[Biosorption of heavy metals by bacteria isolated from activated sludge].
In this paper, biosorption efficiency of heavy metals by bacteria isolated from activated sludge was tested. It was shown that Pseudomonas pseudoalcaligenes and Micrococcus luteus GC subgroup B had high biosorption capacities for Cu(II) and Pb(II) ions. The adsorption of the two ions on Pseudomonas pseudoalcaligenes and Micrococcus luteus GC subgroup B exhibited Langmuir adsorption behavior with regression coefficient of 0.99. The pH value was the most important effect factor on biosorption of metal ions. The biosorption kinetic curves of Cu(II) and Pb(II) ions by cells showed two processes: rapid sorption on cell surface and slowly longer-term transformation into cells. Cu(II) ion can be desorbed effectively from cells of Micrococcus luteus GC subgroup B.
Absorption↗
Validation of microbial recovery from hydrogen peroxide-sterilized air.
The use of hydrogen peroxide as a sanitant in isolators and other barrier systems is well documented. To confirm that the isolator maintains a germ-free environment between decontamination cycles, microbiological air monitoring is performed after the sanitation and aeration cycles. In this study, we have shown that residual levels of hydrogen peroxide as low as 1 ppm can remain in the isolator and inhibit the growth of microorganisms after concentration on agar media. This lingering hydrogen peroxide can make accurate microbiological air monitoring difficult and can even cause false negative test results. To solve this issue, we have developed a new media that can mediate the effects of residual peroxide and prevent false negative test results. Initially, catalase was tested as a neutralizing agent but proved not to be efficient enough. Instead, 1% pyruvate was added, which was able to tolerate as much as 15 ppm Vaporous Hydrogen Peroxide (VHP) and ensured growth promotion of Staphylococcus aureus, Pseudomonas aeruginosa, Micrococcus luteus, Bacillus subtilis, Candida albicans and Aspergillus niger. The 1% pyruvate retained its neutralizing activity for Micrococcus luteus at up to 100 ppm VHP. Raising the pyruvate concentration to 5% pyruvate enabled neutralization of up to 300 ppm VHP, permitting subsequent growth of Micrococcus luteus on agar media.
Air Microbiology↗
[Bacterial reducing qualities of copper-containing and non-copper-containing materials. I. Contamination and sedimentation in humid and dry conditions].
In this examination the bactericide qualities of different materials were tested. Particularly the effect of humidity was examined. 3 materials containing copper ("copper", "brass" and "brass sheet") and 2 materials not containing copper ("polyamide B" and "high-grade steel") were tested. The surfaces of the 5 types of material were contaminated with a suspension of 2 different bacteria species (Staphylococcus aureus and Micrococcus luteus). After defined exposure times the survival rate of the microorganisms on the surfaces was determined by the standardized method of the "Guidelines of the German Society of Hygiene and Microbiology". Additionally the sedimentation of airborne microorganisms on the materials was tested by determining the number of colony-forming-units after defined exposure times. In further examinations the materials were contaminated by hands, which were dipped into a suspension of different microorganisms (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa). The following ways of contaminating the test materials were chosen: single contamination with wet hands, repeated contamination with wet and dry hands. After defined exposure times the survival rate of the microorganisms on the surfaces was determined. The results show, a bactericide quality of copper depends on the percent of copper-content of the tested materials, exposure time, humidity, frequency of contamination and bacteria species. Humidity and only single contamination cause a reduction of bacteria. Reduction of gram-negative bacteria is more easily than reduction of gram-positive bacteria. Enterococcus faecium shows the highest, Pseudomonas aeruginosa the lowest reduction rate of bacteria in the following sequence: Enterococcus faecium, Escherichia coli, Enterobacter cloacae, Micrococcus luteus, Staphylococcus aureus and Pseudomonas aeruginosa.
Air Microbiology↗
Cloning and expression of a gene encoding Moraxella sp. CK-1 autolysin.
A gene of Moraxella sp. CK-1 encoding cell wall lytic activity has been cloned and expressed in E. coli. A genomic library of Moraxella sp. CK-1 was constructed in the multifunctional phagemid vector pT7T3 19u, with partial Sau3A digests of Moraxella sp. CK-1 genomic DNA inserted at the BamHI restriction site. Screening of about 5,000 transformants for cell lysis activity in LB agar plates containing Micrococcus Iuteus cells gave one positive clone harboring the 3.7 kb insert (pMXA282). Restriction mapping and deletion analysis of the recombinant plasmid carrying a 3.7 kb insert suggested that the autolysin gene was located within a 1.1 kb BamHI-PstI fragment. Analysis of extracts of E. coli clone harboring recombinant plasmids on renaturing SDS-polyacrylamide gels containing heat-killed Micrococcus luteus cells showed a clear zone around a polypeptide of about 32 kDa. Lytic activity against Micrococcus luteus cell walls by the cloned autolysin was maximum at pH 9.0. Even in conditions of over pH 10.0, this cloned autolysin showed a vigrous lytic activity. Southern blot analysis suggested the existence of other homologous regions in Moraxella sp. CK-1 genome.
Bacteriolysis↗