Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Microbial cooperation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed2002

Effects of oscillating dietary protein on ruminal fermentation and site and extent of nutrient digestion in sheep.

Eight cannulated wethers (BW = 52.5 +/- 5.7 kg) were used in a replicated 4 x 4 Latin square designed experiment to evaluate the effects of oscillating dietary protein concentrations on ruminal fermentation, site and extent of digestion, and serum metabolite concentrations. Four treatments consisted of a 13, 15, or 17% CP diet fed daily or a regimen in which dietary CP was oscillated between 13 and 17% on a 48-h basis (ACP). All diets consisted of 65% bromegrass hay (10.5% CP, 61.9% NDF, 37.2% ADF) plus 35% corn-based supplement and were formulated to contain the same amount of degradable intake protein (9.6% of DM) plus additional undegradable intake protein (SoyPLUS, West Central Cooperative, Ralston, IA) to accomplish CP levels above 13%. Each of four experimental periods were 16 d in duration with 12 d for diet adaptation followed by 4 d for sample collection. All wethers were fed at 3.0% of initial BW (DM basis) throughout the experiment, resulting in an average organic matter intake of 1.39 kg/d across treatments. When compared to the 15% CP daily treatment, feeding ACP had no effect (P > or = 0.10) on ruminal or lower tract N, NDF, ADF, or OM digestion. True ruminal OM digestion responded quadratically (P = 0.07) to increasing dietary CP, reaching a maximum of 52.0% of OM intake with the 15% CP treatment. Sheep fed ACP tended to have lower (P = 0.08) ruminal NH3 N concentrations and an overall higher (P = 0.0001) molar proportion of acetate compared to those fed 15% CP daily. Total VFA concentrations were not affected (P > or = 0.45) by increasing dietary CP. Microbial efficiency did not differ (P > or = 0.55); thus, bacterial N flow at the duodenum responded quadratically (P = 0.04) to increasing dietary CP. Nonbacterial N (P = 0.001) and total N (P = 0.01) flows at the duodenum and total tract N digestibility (P < or = 0.04) increased linearly as dietary CP increased. Wethers fed ACP maintained a lower (P = 0.002) serum glucose and lower (P = 0.0006) serum urea N compared to those fed 15% CP daily. Because the CP content of the diet was increased at the expense of corn, the response to increased CP observed in this experiment is most likely due to negative associative effects of supplemental starch on ruminal fermentation and microbial growth. Oscillating the CP content of the diet on a 48-h basis has little effect on digestion or N utilization in sheep compared with feeding the same quantity of protein on a daily basis.

Animal Feed↗
PubMed1994

Benzomalvins, new substance P inhibitors from a Penicillium sp.

In the course of screening microbial broths for neurokinin receptor antagonists, a series of new benzodiazepines, benzomalvins A (1), B (2) and C (3), has been isolated from the culture broth of a fungus identified as a Penicillium sp. Benzomalvin A (1) showed inhibitory activity against substance P with Ki values of 12, 42 and 43 microM at the guinea pig, rat and human neurokinin NK1 receptors, respectively. Benzomalvins B (2) and C (3) were only weakly active. The structures of these compounds were determined by spectroscopic methods including MS measurements and NMR analysis.

Animals↗
PubMed1988

Antibiotic susceptibility of bacteria isolated from active, therapy-resistant periodontal sites.

Periodontally affected sites may show resistance to mechanical therapy associated with conventional treatment. This periodontal situation is the result of the cooperation of bacteria, and in some cases the development of superinfections due to opportunistic bacteria is possible. These situations need particular attention in the choice of antibiotics. From some sites, bacteria not commonly found as periodontal pathogens may be isolated; they are generally resistant to antibiotics administered in periodontal therapy. Attention should be used particularly in cases where lesions most resemble those characteristic of the action of gram-negative bacteria. According to results of the present research these cases should be managed with antibiotic combinations and conventional mechanical therapy.

Adolescent↗
PubMed1982

A candidate reference method for uric acid in serum. I. Optimization and evaluation.

We describe our optimization and evaluation of a candidate Reference Method for uric acid in serum. Reaction parameters were optimized for a manual, enzymic method for uric acid in which highly purified microbial uricase is used to quantitate uric acid by a differential ultraviolet procedure. We evaluated the method in terms of freedom from interferences, analytical recovery, precision, and comparison with five other uric acid methods. We conclude that (a) the candidate uric acid Reference Method exhibits the least interference; (b) all six methods exhibit satisfactory analytical recoveries and precision; and (c) results by all six methods agree well. As a result of this evaluation study, the manual ultraviolet uricase method for uric acid, with Tris as buffer, was chosen as the candidate Reference Method for uric acid.

Adult↗
PubMed2001

V beta 6+ and V beta 4+ T cells exert cooperative activity in clearance of secondary infection with Histoplasma capsulatum.

We previously studied the lung Vbeta TCR repertoire of C57BL/6 mice during primary infection with the pathogen Histoplasma capsulatum. We observed a consistent oligoclonal expansion of Vbeta4(+) T cells during the peak of infection and early stages of resolution. The Vbeta4(+) family played a role in protective immunity against the fungus. Depletion of this subpopulation of T cells hindered optimal clearance of infection from tissues. In this report we analyze the flux of the Vbeta TCR repertoire in the lungs of C57BL/6 mice with reinfection histoplasmosis. We observed a significant increase in Vbeta6(+) T cells on days 7, 10, and 14, the peak and early resolution phases of infection. This skewing was preceded by an increased number of memory T cells within Vbeta6(+) cells. The VDJ sequences of Vbeta6 chains were oligoclonal during the early stages of the infection, suggesting that the expansion was driven by a small number of Ags. More than 96% of the expanded Vbeta6(+) cells were CD4(+). Depletion of Vbeta6(+) T cells but not Vbeta4(+) T cells induced a modest but significant delay in fungal clearance. Simultaneous depletion of Vbeta4(+) and Vbeta6(+) T cells induced a more pronounced impairment of host resistance. These studies illustrate the dynamic interactions between Vbeta families in the response to microbial challenge.

Amino Acid Sequence↗
PubMed1976

Cooperative control of translational fidelity by ribosomal proteins in Escherichia coli. III. A ram mutation in the structural gene for protein S5 (rpx E).

The effect on translational fidelity of a particular mutation in the gene coding for protein S5(rpxE) has been investigated. This mutation has the opposite effect of a restrictive strA mutation; in vivo, it relieves the restriction imposed by strA on the suppression of T4 nonsense mutants and results in hypersensitivity to streptomycin; in vitro, the presence of the altered S5 protein in 30S ribosomes results in increased intrinsic misreading. It is concluded that this mutation, ramC319, acts as a ribosomal ambiguity mutation similar to certain mutations of protein S4 (ramA).

Bacterial Proteins↗
PubMedDate not supplied

[Studies on the growth and reproduction of bacterial communities on structural materials of the international space station].

Probability of microbial growth and reproduction on the ISS interior and equipment materials varying in chemical composition was studied with the strains of Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus saprophyticus, Pseudomonas putida etc. sampled from the ISS environment. Controls were ground reference strains of same bacterial species. Based on our results, some of the microorganisms are able to survive and proliferate on structural materials; the ability was greater in space isolates as compared with their ground analogs. The greatest ability to grow and proliferate on materials was demonstrated by Bacillus subtilis.

Bacillus subtilis↗
PubMed2006

Structural determinants for the membrane interaction of novel bioactive undecapeptides derived from gaegurin 5.

Gaegurin 5 is a 24-residue, membrane-active antimicrobial peptide isolated from the skin of an Asian frog, Rana rugosa. We recently reported the antimicrobial activities of two novel undecapeptides derived from an inactive N-terminal fragment (residues 1-11) of gaegurin 5 (Won, et al. J. Biol. Chem. 2004, 279, 14784-14791). In the present work, the anticancer activities of the two antimicrobial undecapeptide analogues were additionally identified. The relationships between their structural properties and biological activities were assessed by characterizing the fundamental structural determinant for the basic membrane interaction. The circular dichroism and nuclear magnetic resonance results revealed that in a membrane-mimetic environment, the active peptides adopt a more stabilized helical conformation than that of the inactive fragment, and this conformation conferred an overall amphipathicity to the active peptides. Therefore, the most decisive factor responsible for the activity and selectivity could be the intramolecular amphipathic cooperativity, rather than the amphipathicity itself. Especially, the tryptophan residue of the active peptides seems to play a crucial role at the critical amphipathic interface that promotes and balances the amphipathic cooperativity by stabilizing both the hydrophilic and hydrophobic interactions with the membrane. Altogether, the present results suggest that the two novel undecapeptides are worthy of therapeutic development as new antibiotic and anticancer agents and provide structural information about their action mechanism.

Amino Acid Sequence↗
PubMed1994

Interaction of the catalytic and the membrane subunits of an oxyanion-translocating ATPase.

Resistance to arsenical and antimonial compounds in Escherichia coli is due to active extrusion of these compounds from cells expressing the ars operon. The arsenical pump is an ion-translocating ATPase which consists of two polypeptide components, the ArsA and ArsB proteins. The ArsB protein, the inner membrane component of the pump, has been shown to function as the membrane anchor for the catalytic subunit, the ArsA protein. The properties and nature of interaction between these two components of the pump were investigated using an in vitro binding assay. Purified ArsA protein bound to the membrane in a saturable manner. In the absence of arsenite or antimonite an apparent positive cooperativity in the binding of the ArsA protein to membrane vesicles containing the ArsB protein was observed. In the presence of arsenite or antimonite binding became hyperbolic, with a 10-fold decrease in the concentration of ArsA protein required for half-maximal binding, without any change in the stoichiometry of the complex. Addition of ATP had little affect on membrane binding of the ArsA ATPase subunit. In the presence or absence of the anionic substrates binding was maximal in a pH range 7.5-8.5.

Adenosine Triphosphatases↗
PubMed2006

Involvement of Toll-like receptor 5 in the recognition of flagellated bacteria.

Toll-like receptors (TLRs) are key components of the immune system that detect microbial infection and trigger antimicrobial host defense responses. TLR5 is a sensor for monomeric flagellin, which is a component of bacterial flagella known to be a virulence factor. In this study we generated TLR5-deficient mice and investigated the role of TLR5 signaling in the detection of flagellin and antibacterial immune responses to Salmonella typhimurium and Pseudomonas aeruginosa. We found that TLR5 is essential for the recognition of bacterial flagellin both in vivo and ex vivo. TLR5 contribution to antibacterial host response to i.p. infection with S. typhimurium or intranasal administration of P. aeruginosa may be masked by TLR4 or other sensing mechanisms. By using radiation bone marrow chimera, we showed that upon i.p. injection of flagellin immune responses are mediated by lymphoid cells, whereas resident cells are required for the initiation of response upon intranasal flagellin administration. These results suggest that flagellin recognition in different organs is mediated by distinct TLR5-expressing cells and provide insights into the cooperation of the TLR5 and TLR4 signaling pathways used by the innate immune system in the recognition of bacterial pathogens.

Animals↗
PubMed1992

[Synergistic action of cefodizime and other antimicrobial agents on clinically isolated microorganisms. III. Synergistic action with gentamicin].

An in vitro investigation was done on antimicrobial activities of cefodizime (CDZM) in combination with gentamicin (GM) against clinically isolated Gram-negative rods. The results are summarized as follows. 1. Combined antimicrobial activities were dependent on antimicrobial activities of GM, similar to the CDZM + sisomicin (SISO) combination. The combined activities were concentration dependent, and they were more strongly dependent on GM concentrations than on CDZM concentrations. The obtained results suggested that synergistic or cooperative antimicrobial activities of the combination would be expected when GM concentrations in blood are at or somewhat lower than 1 MIC, and clinical activities would be exerted regardless of the presence of CDZM resistant organisms, similarly to CDZM+SISO combination. 2. It seems possible that, with regard to combinations of beta-lactam antibiotics and aminoglycoside antibiotics, there exist universal rules that combined activities are dependent on activities of aminoglycoside antibiotics, and that stronger concentration dependencies on aminoglycosides would be observed than those on beta-lactams.

Bacteria↗
PubMedDate not supplied

[Occurrence of chemical and antibiotic resistance of non-human Salmonella serotypes].

A survey on Salmonella serotypes isolated from livestock, foods of animal origin and surface waters has been performed by the Reference Center for Enterobacteria of Northern Italy in cooperation with the Multi-Regional Veterinary Public Health Laboratories of Northern Italy, and the results were compared with the range of Salmonella isolates from humans. Major differences have resulted in the frequencies of the different serotypes, being Group B serotypes by far less frequently isolated from humans. Nevertheless, S. typhi-murium was the individual serotype prevalent in both sources. A selected group of strains, of either origin, has been tested for chemo-antibiotic resistance, which showed to be more widespread in the non-human strains.

Animal Feed↗
PubMedDate not supplied

Effects of subminimal inhibitory concentrations of beta-lactam antibiotics against R-plasmid-bearing bacteria.

The effects of subminimal inhibitory concentrations (sub-MICs) of nine beta-lactam antibiotics [penicillin-G, ampicillin (ABPC), cloxacillin, dicloxacillin, nafcillin, cephalothin, cephradine, cefazolin (CEZ) and cefoxitin] against seven different R-plasmid-bearing gram-negative bacterial strains were tested. Morphological changes, such as filamentous development and lysis, occurred at concentrations considerably lower than the MIC values and the presence of R plasmids did not influence the morphological changes compared with those of Escherichia coli NIHJ, which is non-R-plasmid-bearing. Clear cooperation of ABPC and CEZ with rabbit polymorphonuclear leukocytes PMNs against Pseudomonas aeruginosa and Proteus vulgaris and of CEZ against Salmonella typhimurium was observed, but not against the other strains tested. Therefore, the filamentous bacteria produced as a result of exposure to sub-MICs of antibiotics were not always phagocytosed easily. The ratios between the drug concentrations (microgram/ml) at which the morphological changes began to occur (minimal antibiotic concentration) and the MIC values (microgram/ml) were calculated. A large ratio indicated a wide range of effective concentrations below the MIC value for that antibiotic.

Ampicillin↗
PubMed1999

5-Cyanovaleramide production using immobilized Pseudomonas chlororaphis B23.

A biocatalytic process for the hydration of adiponitrile to 5-cyanovaleramide has been developed which can be run to higher conversion, produces more product per weight of catalyst, and generates significantly less waste products than alternate chemical processes. The biocatalyst consists of Pseudomonas chlororaphis B23 microbial cells immobilized in calcium alginate beads. The cells contain a nitrile hydratase (EC 4.2.1.84) which catalyzes the hydration of adiponitrile to 5-cyanovaleramide with high regioselectivity, and with less than 5% selectivity to byproduct adipamide. Fifty-eight consecutive batch reactions with biocatalyst recycle were run to convert a total of 12.7 metric tons of adiponitrile to 5-cyanovaleramide. At 97% adiponitrile conversion, the yield of 5-cyanovaleramide was 13.6 metric tons (93% yield, 96% selectivity), and the total weight of 5-cyanovaleramide produced per weight of catalyst was 3150 kg/kg (dry cell weight).

Amides↗
PubMed2005

Identification and functional characterization of three chicken cathelicidins with potent antimicrobial activity.

Cathelicidins comprise a family of antimicrobial peptides sharing a highly conserved cathelin domain. Here we report that the entire chicken genome encodes three cathelicidins, namely fowlicidin-1 to -3, which are densely clustered within a 7.5-kb distance at the proximal end of chromosome 2p. Each fowlicidin gene adopts a fourexon, three-intron structure, typical for a mammalian cathelicidin. Phylogenetic analysis revealed that fowlicidins and a group of distantly related mammalian cathelicidins known as neutrophilic granule proteins are likely to originate from a common ancestral gene prior to the separation of birds from mammals, whereas other classic mammalian cathelicidins may have been duplicated from the primordial gene for neutrophilic granule proteins after mammals and birds are diverged. Similar to ovine cathelicidin SMAP-29, putatively mature fowlicidins displayed potent and salt-independent activities against a range of Gram-negative and Gram-positive bacteria, including antibiotic-resistant strains, with minimum inhibitory concentrations in the range of 0.4-2.0 microm for most strains. Fowlicidin-1 and -2 also showed cytotoxicity, with 50% killing of mammalian erythrocytes or epithelial cells in the range of 6-40 microm. In addition, two fowlicidins demonstrated a strong positive cooperativity in binding lipopolysaccharide (LPS), resulting in nearly complete blockage of LPS-mediated proinflammatory gene expression in RAW264.7 cells. Taken together, fowlicidin-1 and -2 are clearly among the most potent cathelicidins that have been reported. Their broad spectrum and salt-insensitive antibacterial activities, coupled with their potent LPS-neutralizing activity, make fowlicidins excellent candidates for novel antimicrobial and anti-sepsis agents.

Amino Acid Sequence↗
PubMed1991

Binding affinities of structurally related human rhinovirus capsid-binding compounds are related to their activities against human rhinovirus type 14.

The binding affinities (Kds) and the rates of association and dissociation of members of a chemical class of antiviral compounds at their active sites in human rhinovirus type 14 (HRV-14) were determined. On the basis of analysis by LIGAND, a nonlinear curve-fitting program, of saturation binding experiments with HRV-14, the Kds for Win 52084, Win 56590, disoxaril (Win 51711), and Win 54954 were found to be 0.02, 0.02, 0.08, and 0.22 microM, respectively. The independently determined kinetic rates of association and dissociation resulted in calculated Kd values which were in agreement with the Kd values determined in saturation binding experiments. Scatchard plots of each of four compounds for the binding data indicated that approximately 40 to 60 molecules were bound per HRV-14 virion. Hill plots showed no evidence of cooperativity in binding. Furthermore, the antiviral activities (MICs in plaque reduction assays with HRV-14) for this limited series of compounds (n = 4) correlated well (r = 0.997) with the observed Kds. Likewise, the absence of detectable binding of Win 54954 to the drug-resistant mutant HRV-14 (Leu-1188) corresponded to a lack of antiviral activity. The positive relationship between the antiviral activities and the Kds that were determined may have implications for the molecular design of capsid-binding antirhinovirus drugs.

Antiviral Agents↗
PubMed2003

Termite symbiotic systems: efficient bio-recycling of lignocellulose.

Termites thrive in great abundance in terrestrial ecosystems and play important roles in biorecycling of lignocellulose. Together with their microbial symbionts, they efficiently decompose lignocellulose. In so-called lower termites, a dual decomposing system, consisting of the termite's own cellulases and those of its gut protists, was elucidated at the molecular level. Higher termites degrade cellulose apparently using only their own enzymes, because of the absence of symbiotic protists. Termite gut prokaryotes efficiently support lignocellulose degradation. However, culture-independent molecular studies have revealed that the majority of these gut symbionts have not yet been cultivated, and that the gut symbiotic community shows a highly structured spatial organization. In situ localization of individual populations and their functional interactions are important to understand the nature of symbioses in the gut. In contrast to cellulose, lignin degradation does not appear to be important in the gut of wood-feeding termites. Soil-feeding termites decompose humic substances in soil at least partly, but little is known about the decomposition. Fungus-growing termites are successful in the almost complete decomposition of lignocellulose in a sophisticated cooperation with basidiomycete fungi cultivated in their nest. A detailed understanding of efficient biorecycling systems, such as that for lignocellulose, and the symbioses that provide this efficiency will benefit applied microbiology and biotechnology.

Animals↗
PubMed2004

Camptothecin induces the ubiquitin-like protein, ISG15, and enhances ISG15 conjugation in response to interferon.

Interferon (IFN)-stimulated gene (15 kDa) (ISG15) is a ubiquitin-like protein that forms covalent conjugates with cellular proteins. ISG15 is induced by IFN, microbial challenge, and p53, suggesting that it represents a genetic response that is shared among diverse stress stimuli. To investigate the regulation of this posttranslational modification pathway by a genotoxic chemotherapeutic agent, we examined ISG15 induction and conjugation in cells treated with the topoisomerase I (topoI) poison, camptothecin (CPT). CPT induced ISG15mRNA, and induction required protein synthesis and a functional p53 protein. However, IFN and the Jak-Stat components of the IFN signaling pathway were dispensable for CPT induction of ISG15. CPT induced free ISG15 and conjugates in a dose-dependent and time-dependent manner. A single 55-kDa protein was the prominent CPT-induced ISG15 conjugate and localized to the nuclear compartment. CPT-induced ISG15 conjugates were distinct from those induced by IFN; however, CPT treatment dramatically enhanced ISG15 conjugation in response to IFN. These findings provide the first evidence of a stimulus-specific induction of discrete ISG15 conjugate species and demonstrate that treatment with a combination of cancer therapeutic agents can cooperate to enhance ISG15 conjugation. Identification of the specific ISG15 conjugates induced by chemotherapeutic agents may reveal novel molecular targets.

Antineoplastic Agents, Phytogenic↗