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PubMed1986

Chromatin structure and induction-dependent conformational changes of human interferon-beta genes in a mouse host cell.

Multiple copies of a human interferon-beta gene introduced into a mouse host cell line can be activated by induction with double-stranded RNA. Several induction-dependent changes of the chromatin structure could be traced by mapping techniques using four different agents [DNase I, micrococcus nuclease, bromoacetaldehyde and methidiumpropyl-EDTA X iron(II)]. Our data show that all copies of the interferon gene have adopted a very similar conformation in the host cell and respond to the inducing stimulus in a highly synchronous fashion. Detailed induction-specific changes were observed best with the chemical reagents which disclose a specific hypersensitive site within a sequence that has been shown to be required for the induction process (around position -80) and three other regions which, in addition to the transcribed region itself, gain single-strand character by an auxiliary process which can be mimicked by the addition of butyrate to the medium and may therefore involve histone hyperacetylation. Six discrete 'phased' nucleosomes are present upstream from the gene and are modulated by induction. At least four nucleosomes are located downstream. The interferon genes are largely protected from micrococcus nuclease in the inactive state. Gene activation increases access to micrococcus nuclease and DNase I indicating gross conformational changes on a higher level of chromatin structure.

Animals↗
PubMed1968

Effect of gamma irradiation on the microflora of freshwater fish. 3. Spoilage patterns and extension of refrigerated storage life of yellow perch fillets irradiated to 0.1 and 0.2 megarad.

Maximal shelf life was determined and microbial flora were compared for irradiated (0.1 and 0.2 Mrad) and nonirradiated yellow perch fillets stored at 1 C. Shelf life was estimated by organoleptic determinations. Microbiological studies included determination of the effects of irradiation on the total aerobic microbial population, lag phase, and rate of growth. Genera of organisms isolated from fillets through the course of microbial spoilage were identified, and the proteolytic activity of the organisms was determined. Plate counts for fish prior to irradiation showed the presence of approximately 10(6) organisms per g of sample. Irradiation to 0.1 and 0.2 Mrad produced 1.4 and 3 logarithm reductions of the initial count, respectively. Irradiation to 0.1 and 0.2 Mrad approximately doubled the product's shelf life. Organisms initially isolated from the nonirradiated fillets, in order of decreasing number, consisted of Flavobacterium, Micrococcus-Sarcina, Achromobacter-Alcaligenes-Mima, Pseudomonas, Microbacterium, Vibrio, Bacillus, Corynebacterium, Lactobacillus, Brevibacterium, and Aeromonas. By the 6th and 9th days of fillet storage, Pseudomonas and the Achromobacter group were the predominant organisms. All members of the genus Flavobacterium, but not all members of the genus Pseudomonas, were proteolytically active on raw fish juice-agar and skim milk-agar media. The Achromobacter group was found to be nonproteolytic on both media. Residual flora of fillets irradiated to 0.1 and 0.2 Mrad consisted of the Achromobacter group, Lactobacillus, Micrococcus-Sarcina, and Bacillus. Their sequence in predominance, however, varied with dose level. Not all proteolytic bacteria in the fillets were eliminated by 0.1 and 0.2 Mrad; proteolytic Micrococcus-Sarcina survived these treatments.

Bacteria↗
PubMed2002

The antibacterial activity of topical retinoids: the case of retinaldehyde.

BACKGROUND: Retinoids such as retinoic acid (RA), retinol (ROL) and retinaldehyde (RAL) are currently used in many formulations and indications ranging form acne to skin aging. Most if not all their pharmacological activities occur through binding to nuclear receptors with subsequent modulation of the activities of several genes. Little attention has been given to the many other potential actions on the surface of the skin. AIM: To analyse the potential anti-infective activities of topical ROL, RAL and RA. METHODS: Microbial minimal inhibitory concentrations (MIC) of ROL, RAL and RA were determined by a microdilution method on reference strains including Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus flavus, Propionibacterium acnes, Micrococcus luteus, Enterococcus faecium, Staphylococcus hominis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and 133 clinical strains including methicillin-resistant S. aureus, methicillin-sensitive S. aureus, coagulase-negative Staphylococcus, Streptococcus group B, Enterococcus faecalis, vancomycin-resistant E. faecalis, vancomycin-resistant E. faecium and Pseudomonas/Klebsiella. In two clinical trials in healthy human volunteers, skin bacterial densities were evaluated in samples obtained with the cylinder scrub method: (1). 2 and 5 h after a single application of 0.05% RAL or vehicle on the forearm and (2). in a single-blind randomized study where 0.05% RAL or vehicle were applied daily for 2 weeks on the forehead of 22 volunteers. Paired results from treated (or vehicle) and untreated areas were analysed. RESULTS: Of the three retinoids tested, only RAL showed a significant in vitro antibacterial activity; this activity was found against reference strains of gram-positive bacteria like S. aeureus, Micrococcus spp. or P. acnes. No activity was found against gram-negative bacteria. These results on reference strains were confirmed on 133 clinical isolates. MIC(50) and MIC(90) values for RAL were 8 and 16 mg/l, respectively, for methicillin-sensitive S. aureus and 4 and 8 mg/l for methicillin-resistant S. aureus. The two in vivo studies showed that areas treated with RAL had a significant decrease in the bacterial counts. In the forehead study, the median decrease was 10(2) log/cm(2) for P. acnes and 10(1.8) log/cm(2) for staphylococci. No resistant bacteria were found after 2 weeks of topical use. Preliminary results suggest that the antibacterial effect of RAL is due, in part, to the aldehyde group in the lateral chain, since non-retinoid pseudo-analogues of the chain, like citral and hexenal, showed a similar antibacterial activity. CONCLUSION: We have shown that RAL differs from parent natural retinoids such as ROL and RA in demonstrating significant antibacterial activities upon topical use. This activity is likely due to the aldehyde group in the isoprenoic lateral chain, which illustrates the potential bifunctional properties of some retinoids.

Bacteria↗
PubMedDate not supplied

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↗
PubMed1957

Staphylococcal virolysin, a phage-induced lysin; its differentiation from the autolysis of normal cells.

Virolysin is a lysin which appears in Staphylococcus aureus K(1) cells infected with phage P(14); together with phage, virolysin is released from phage-infected cells at the time of lysis. Autolysin is a lysin formed by uninfected cells of the K(1) strain; autolysin is released from uninfected cells by autolysis. They show the following similarities: Both agents act within the genus Micrococcus. They lyse cells only after the cell has been subjected to a damaging or "sensitizing" treatment, such as heat, bacteriophage, acetone, or ultraviolet irradiation. The course of lysis of heated cells by both lysins has been found to proceed in a similar manner. A constant percentage of cells is lysed, independent of the concentration of lysin; the residual cells remain resistant to either lysin. Lysis proceeds logarithmically with time, and the velocity constants K are proportional to the lysin concentration. K increases with increasing temperature. Both lysins are unaffected by antiserum to the phage. They are inhibited alike by a number of chemicals, including known enzyme inhibitors. Both agents are destroyed by proteolytic enzymes and are precipitated by 40 per cent saturation with (NH(4))(2)SO(4). Both lysins are very thermolabile. The two lysins differ with respect to their pH optimum, antigenic relationship and specificity for Micrococcus lysodeikticus. These results suggest that (1) both lysins have many properties associated with enzymes, (2) the lysis of heated cells, which they produce, has some of the characteristics of a chemical reaction, (3) the lysin from the phage-infected cell is clearly different from the lysin of the uninfected cell.

Autolysis↗
PubMed1991

Cibacron blue 3G-A inhibits cell separation of gram-positive bacteria.

A triazine dye, Cibacron blue 3G-A (CB), is an inhibitor of cell separation of staphylococcal spp. therefore, we examined the effect of CB on growth of gram-positive bacteria other than Staphylococcus. CB added to the medium of growing cultures of strains of genus Micrococcus, Streptococcus, Lactobacillus and Bacillus caused inhibition of cell separation. Moreover, in case of Bacillus and Lactobacillus, individual cells were elongated as filament. Strains of the genus Micrococcus were as sensitive to CB as genus Staphylococcus in which the minimum concentrations of CB needed for inhibition of cell separation ranged from 15 to 100 microM. Other strains belong to genus Streptococcus, Bacillus and Lactobacillus were less sensitive; the minimum concentrations were 100 microM--25 mM.

Bacillus↗
PubMed1978

Specific antibodies to the N-termini of the interpeptide bridges of peptidoglycan.

The synthetic peptides Gly5-epsilon-Ahx and L-Ala3-epsilon-Ahx, with structural similarity to the interpeptide bridge peptides of staphylococci or micrococci, respectively, were convalently linked to human serum albumin via their carboxylgroups. Antisera to these synthetic peptidyl-protein antigens contained fairly high amounts of antibodies with specificity to the N-terminal parts of the peptide chains attached to the carrier proteins. Antisera to (Gly5-epsilon-Ahx)20-albumin gave, without exception, strong precipitin reactions in latex-agglutination with staphylococcal peptido-glycans. The antisera completely failed, however, in any reaction with peptidoglycans of micrococci or other bacteria which did not have these oligo-glycine peptides typical for staphylococci. On the contrary, antisera to (l-Ala3-epsilon-Ahx)22-albumin strongly precipitated micrococcalpeptidoglycans with oligo-L-alanine interpeptide bridges (e.g. Micrococcus varians. Micrococcus roseus), but showed no significant reaction with peptidoglycans of staphylococci or other bacteria lacking oligo-L-alanine interpeptide bridges.

Animals↗
PubMed1991

The occurrence and growth of microorganisms during the fermentation of fish sausage.

Minced fish (mullet) sausage mixes containing added sugar, salt, nitrate, nitrite and spices were fermented (48 h, 30 degrees C) by indigenous flora or by a starter culture (Pediococcus acidilactici) and the microbial ecology and behaviour of various bacteria was monitored. Pediococcus pentosaceus and Lactobacillus plantarum dominated the indigenous fermentation, achieving populations of 10(7)-10(8) cfu/g by 48 h, and decreasing the pH of the mix to 4.5-4.7. Significant growth (10(5)-10(7) cfu/g) of Staphylococcus warneri, Staphylococcus aureus, Staphylococcus epidermidis. Micrococcus varians and Micrococcus luteus also occurred during this fermentation. Less growth was exhibited by Bacillus megaterium and yeasts. Pediococcus acidilactici dominated the fermentation when it was inoculated as a starter culture, but indigenous lactic acid bacteria (P. pentosaceus and L. plantarum) also grew to 10(7)-10(8) cfu/g. The growth of other bacteria and yeasts was restricted during fermentation with starter culture. Inoculated Escherichia coli, Salmonella typhimurium, Salmonella sofia, and Staphylococcus aureus grew to 10(6)-10(7) cfu/g in the sausage mix during indigenous fermentation. Lesser growth occurred for Bacillus cereus, Clostridium perfringens and Vibrio parahaemolyticus. Growth of these bacteria was significantly inhibited in sausage mix fermented with P. acidilactici.

Animals↗
PubMed1994

Identification of psychrotrophic Micrococcaceae spp. isolated from fresh beef stored under carbon dioxide or vacuum.

Seventy-four Gram-positive, catalase-positive coccal strains were isolated from fresh beef stored under carbon dioxide (< 500 ppm O2) or vacuum for up to 15 weeks at 0, 2 or 4 degrees C. Isolates were identified using biochemical tests listed in several published protocols and the API Staph-Ident System. No isolates were identified as Staphylococcus aureus. Twenty-nine isolates were identified as Staphylococcus saprophyticus (five distinct groups), 24 isolates were identified as Staphylococcus gallinarum and 21 isolates were identified as Micrococcus varians. The staphylococcal isolates were coagulase-negative, non-hemolytic and novobiocin resistant. They produced acid from several carbohydrates under aerobic conditions, hydrolysed gelatin but not collagen, showed lipolytic activity and grew in 15% NaCl. The Micrococcus varians isolates also were salt-tolerant, produced acid only from glucose, fructose and galactose (two strains), and were resistant to lysozyme (1600 micrograms/ml). Lactic acid was the major end product of aerobic glucose metabolism. All S. saprophyticus and M. varians isolates tested contained cell wall fatty acids with chain length > or = C20:0.

Animals↗
PubMed1990

Hygienic hand disinfection: a comparative study with chlorhexidine detergents and soap.

The efficacy of two chlorhexidine hand-wash detergents and liquid soap was compared in a laboratory trial using artificial contamination of fingers with Micrococcus and Serratia. Agents were assessed for both a rapid and sustained effect after a single contact, and for a cumulative persistent effect after multiple contact over four days. Disinfectant activities were compared by statistical analysis of log reduction factors and log count time gradients (decimal reduction times). The latter analysis attempted to accommodate significant subject variation in response to both agent and organism. All handwashing methods significantly reduced contamination levels. Both chlorhexidine formulations were significantly better than soap in their activity against Micrococcus, but were not more effective than soap in removing contamination with Serratia. Both chlorhexidine preparations showed significant skin persistence and were generally acceptable to subjects after prolonged use. Some effect of the formulation of the hand-wash on chlorhexidine activity was demonstrated.

Chlorhexidine↗
PubMed1986

Seasonal variation and characterization of Micrococcaceae present in ewes' raw milk.

Samples (120) of ewes' raw milk collected over a 12-month period on arrival at the dairy and freshly drawn ewes' milk samples (30) collected at the farm were analysed for total viable counts and staphylococci. Total viable counts reached on the average 5.4 X 10(6)/ml in dairy samples and 6.0 X 10(5)/ml in farm samples, whereas mean levels of staphylococci were 5.9 X 10(4)/ml and 3.3 X 10(3)/ml, respectively. A high proportion (62%) of coagulase-positive isolates from Baird-Parker agar plates was detected in spring months. Staphylococcus aureus (42%), Staph. haemolyticus (23%) and Staph. epidermidis (10%) were the predominant species in 210 characterized isolates of staphylococci from ewes' raw milk. Seven coagulase-positive, maltose-negative staphylococci could not be identified with any of the recognized Staphylococcus species. Eighteen Micrococcus strains were identified as M. varians, whereas 111 Micrococcus strains of uncertain taxonomic status were separated into three groups, according to their physiological characters.

Animals↗
PubMed2002

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↗
PubMed1999

Contribution of the microbial and meat endogenous enzymes to the free amino acid and amine contents of dry fermented sausages.

The role of the starter culture and meat endogenous enzymes on the free amino acid and amine contents of dry fermented sausages was studied. Five batches of sausages were prepared. The control batch was manufactured with aseptic ingredients without microbial inoculation. The other four experimental batches were manufactured with aseptic ingredients inoculated with Lactobacillus plantarum 4045 or Micrococcus-12 or L. plantarum 4045 and Micrococcus-12 or L. plantarum 4045 and Staphylococcus sp. Their effects on pH, a(w), myofibrillar proteins, and free amino acid and amine contents were studied. Sausages inoculated only with L. plantarum 4045 or with this starter combined with a Micrococcaceae had the lowest pH as a result of carbohydrate fermentation. In all batches similar patterns were observed for myofibrillar proteins and free amino acids which could indicate that meat endogenous proteases play an important role in proteolytic phenomena. No changes were observed in the amine fraction, indicating that the strains used as starter cultures did not show amino acid decarboxylase activity.

Amines↗
PubMed1997

An evaluation of the microflora associated with fermented African oil bean (Pentaclethra macrophylla Bentham) seeds during ugba production.

The microorganisms associated with fermented African oil bean (Pentaclethra macrophylla Bentham) seed during ugba production was studied. Only bacteria were isolated from the ugba samples used. Although the bacteria included Bacillus spp., Lactobacillus spp., Staphylococcus spp., Micrococcus spp. and members of the family Enterobacteriaceae, only the Bacillus spp. were found to ferment African oil bean seeds to ugba. Bacillus spp. were the predominant microorganisms present, constituting over 95% of the total microbial population density. An increase in the number of Bacillus cells of about 2 log units daily, which attained a maximum density of log10 9.00 - log10 11.90 cfu/g after 3 days was observed. Contrarily, the Lactobacillus spp. increased minimally and attained a maximum value of log10 4.20 - log10 6.35 cfu/g within the same period. The Staphylococcus spp., Micrococcus spp. and the members of the family Enterobacteriaceae remained fairly steady in number for 24h, increased slightly till the 3rd day followed by exponential increases which attained maximum values of between log10 9.20 - log10 11.00, about the 7th day. Bacillus spp. cells also had the highest protease activities which were significantly (p < 0.05) higher than the values for the other bacterial isolates. The Bacillus spp. responsible for the fermentation of African oil bean seeds to ugba were identified as Bacillus coagulans, B. macerans, B. megaterium, B. pumilis and B. subtilis.

Bacillus↗
PubMed2004

Photocatalytic inhibition of microbial adhesion by anodized titanium.

Biofouling is one of the concerns in the use of titanium for seawater cooled condensers of power plants. Earlier studies have shown that anodized titanium and its alloys with a thin film of anatase (TiO(2)) on its surface can inhibit attachment of Pseudomonas sp. when illuminated with near-UV light (350 - 380 nm). In the present study, a comparison of the photocatalytic inhibition of microbial attachment on titanium surfaces anodized at different voltages was carried out. Thin films of anatase of varying thickness were produced on titanium grade-2 by anodizing in dilute orthophosphoric acid solution at 30 V, 50 V and 100 V. The photocatalytic efficiency of these anodized surfaces was measured by the methylene blue degradation method. The anodised surfaces were exposed to liquid cultures of Gram-negative Pseudomonas sp., Gram-positive Micrococcus sp. and to a mixed algal culture. Photocatalytic inhibition of microbial attachment was maximum on the titanium surface anodized at 30 V, followed by the surface anodized at 50 V and then at 100 V. The photocatalytic inhibition of microbial attachment was also found to be dependent on the cell wall characteristics of the organism. The Gram-negative Pseudomonas sp. with a lipoproteinaceous outer membrane was the most susceptible to the photocatalytic effect, while the Gram-positive Micrococcus sp. with peptidoglycan cell wall showed moderate susceptibility and the algae with siliceous cell wall showed no susceptibility at all.

Anti-Bacterial Agents↗
PubMed1979

Autoregulation of an antibody response via network-induced auto-anti-idiotype.

The antibody response of a single outbred rabbit was studied throughout three rounds of injections with Micrococcus lysodeikticus vaccine over a 31-mo period. The first-round response was characterized by a vigorous anti- micrococcus response and a strong anti-IgG rheumatoid factor response. The second-round response consisted of a triad of interacting molecules: anti- micrococcal antibodies, autoanti-idiotypic antibodies specific for distinct clonotypes of the first-round anti-micrococcal antibodies, and Fc-specific anti-IgG rheumatoid factor. The interacting triple complex was detected because of the formation of an immune complex that became insoluble upon dilution of the serum. Complex formation was inhibited in the presence of saccharide compounds known to be major immunodominant determinants of the micrococcal cell-wall carbohydrate polymer. The same saccharides did not affect the reaction of rheumatoid factor with IgG. Direct-binding radioimmunoassays ruled out mediation of the dilution-precipitation reaction by soluble micrococcal antigens. Specific absorption of rheumatoid factor inhibited the dilution-precipitation reaction. Auto-anti-idiotypic antibodies were specifically purified from second-round sera, directly confirming the presence of these antibodies. Suppressive effects of auto-anti-idiotypic antibodies on distinct antibody clonotypes were shown by gel isoelectric focusing of first-, second-, and third-round sera. Clonotypes expressed in the first round of immunizations were reduced in quantity or absent when auto-anti-idiotypic antibodies were detectable. Greatly enhanced levels or initial synthesis of new clonotypes of anti-micrococcal antibodies were detected during the period of auto-anti-idiotype synthesis. The third-round sera, devoid of detectable auto-anti-idiotype, contained clonotypes characteristic of both first- and second-round antisera. Thus, auto-anti- idiotypic-mediated suppression appeared to be reversible. The data are interpreted as lending strong support for concepts of autoregulation of immune processes in normal outbred animals via an idiotypic network.

Animals↗
PubMed2004

The structure of resting bacterial populations in soil and subsoil permafrost.

The structure of individual cells in microbial populations in situ of the Arctic and Antarctic permafrost was studied by scanning and transmission electron microscopy methods and compared with that of cyst-like resting forms generated under special conditions by the non-spore-forming bacteria Arthrobacter and Micrococcus isolated from the permafrost. Electron microscopy examination of microorganisms in situ revealed several types of bacterial cells having no signs of damage, including "dwarf" curved forms similar to nanoforms. Intact bacterial cells in situ and frozen cultures of the permafrost isolates differed from vegetative cells by thickened cell walls, the altered structure of cytoplasm, and the compact nucleoid, and were similar in these features to cyst-like resting forms of non-spore-forming "permafrost" bacterial strains of Arthrobacter and Micrococcus spp. Cyst-like cells, being resistant to adverse external factors, are regarded as being responsible for survival of the non-spore-formers under prolonged exposure to subzero temperatures and can be a target to search for living microorganisms in natural environments both on the Earth and on extraterrestrial bodies.

Arthrobacter↗
PubMed1978

The phage adsorption test: a simple method for differentiation between staphylococci and micrococci.

A simple phage adsorption test is recommended for differentiation between staphylococci and micrococci. All 132 strains of Staphylococcus tested inactivated phage U16 significantly, whereas of 123 strains of Micrococcus tested, only three strains of Micrococcus candicans were able to adsorb this staphylococcal phage. There are special problems in the taxonomy of M. candicans.

Adsorption↗