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At least 73 records · Page 4Linked to original sources
PubMed1983

Dialysis membrane technique for studying microbial interaction.

A dialysis membrane method is described which allows (i) cultivation of fungi on an agar support, (ii) observation of growth and development by direct light microscopy, (iii) transfer of cultures from agar surfaces for subsequent treatments or for biochemical analysis, and (iv) preparation for scanning electron microscopy. The method is used routinely in studies of fungus-nematode and fungus-fungus interactions.

Journal Article↗
PubMed1984

Dialysis membrane technique for ultrastructural studies of microbial interactions.

A dialysis membrane technique was developed that enabled ultrastructural investigations of the interaction of nematode-trapping fungi and their nematode prey. It allowed the sectioning of individual traps that had been selected by light microscopy and was used in kinetic studies on trap formation, nematode capture, and subsequent nematode digestion. The method can also be used for enzyme cytochemical experiments.

Animals↗
PubMed1982

Effect of microbial interaction on the colonization rate of Actinomyces viscosus or Streptococcus mutans in the dental plaque of rats.

The resident oral microflora of conventional Osborne-Mendel rats was challenged with Actinomyces viscosus or Streptococcus mutans strains. The adherence of the inoculated organism to the tooth surface and the subsequent growth were studied by means of viable counts determination. The initial growth rate of S. mutans in conventional rats was lower than in mono-associated gnotobiotic rats (doubling time, td = 5 h versus td = 1.1 h). The delayed start of growth and the low initial growth rate indicated that a competitive interaction between S. mutans and the resident microflora occurred. The initial growth rate of A. viscosus in conventional rats (td = 3.1 h) was approximately the same as that in gnotobiotic rats (td = 2.8 h). The start of growth of A. viscosus was only slightly delayed compared with the start in gnotobiotic rats. These results suggest a neutralistic relationship between A. viscosus and the resident microflora. A. viscosus reached a stationary level about 7 days after inoculation, whereas the S. mutans strains did not reach stationary levels until 2 weeks after inoculation.

Actinomyces↗
PubMed2003

Human intestinal epithelial cells are broadly unresponsive to Toll-like receptor 2-dependent bacterial ligands: implications for host-microbial interactions in the gut.

Intestinal epithelial cells (IEC) interact with a high density of Gram-positive bacteria and are active participants in mucosal immune responses. Recognition of Gram-positive organisms by Toll-like receptor (TLR)2 induces proinflammatory gene expression by diverse cells. We hypothesized that IEC are unresponsive to Gram-positive pathogen-associated molecular patterns and sought to characterize the functional responses of IEC to TLR2-specific ligands. Human colonic epithelial cells isolated by laser capture microscopy and IEC lines (Caco-2, T84, HT-29) were analyzed for expression of TLR2, TLR6, TLR1, and Toll inhibitory protein (Tollip) mRNA by RT-PCR and quantitative real-time PCR. Response to Gram-positive bacterial ligands was measured by NF-kappa B reporter gene activation and IL-8 secretion. TLR2 protein expression was analyzed by immunofluorescence and flow cytometry. Colonic epithelial cells and lamina propria cells from both uninflamed and inflamed tissue demonstrate low expression of TLR2 mRNA compared with THP-1 monocytes. IECs were unresponsive to TLR2 ligands including the staphylococcal-derived Ags phenol soluble modulin, peptidoglycan, and lipotechoic acid and the mycobacterial-derived Ag soluble tuberculosis factor. Transgenic expression of TLR2 and TLR6 restored responsiveness to phenol soluble modulin and peptidoglycan in IEC. In addition to low levels of TLR2 protein expression, IEC also express high levels of the inhibitory molecule Tollip. We conclude that IEC are broadly unresponsive to TLR2 ligands secondary to deficient expression of TLR2 and TLR6. The relative absence of TLR2 protein expression by IEC and high level of Tollip expression may be important in preventing chronic proinflammatory cytokine secretion in response to commensal Gram-positive bacteria in the gut.

Bacterial Toxins↗
PubMedDate not supplied

[Some features of tonsillar microflora and microbial interaction (in normal and pathological states)].

The description of a new method for the determination of interaction between bacterial strains isolated from the mucous membrane of tonsils of healthy children and patients with chronic tonsillitis. In the analysis of mutual influence of symbionts on the hemolytic, lecitovitellase, lysozyme and antilysozyme activity of microbes isolated from healthy children no changes in the expression of these pathogenicity and persistence factors have been detected in the overwhelming majority of cases (70.8-89.9%). In the microflora of sick children interactions were synergic with respect to pathogenicity factors in 35.2-46.7% of cases and antagonistic in 18.7-31.3% of cases.

Adolescent↗
PubMed2002

The consequences of volatile organic compound mediated bacterial and fungal interactions.

Microbial interactions via infochemicals are fundamental to the development of spatial distribution and activity variations in ecosystems. Microorganisms produce a wide range of infochemicals, frequently secondary metabolites, most of which are soluble and many volatile. Volatile organic compounds (VOCs) have been identified in soil atmospheres and related to community structure and function. VOC profiles produced by microorganisms are consistent, relating to cultural conditions, environment and inputs, and so to population and function dynamics. VOC-mediated interactions can result in functional responses by the organisms involved that result in selective advantage to some community members. Positive, negative or neutral interactions can occur between a very wide range of soil bacteria and fungi. These effects include both stimulation and inhibition of growth, by 40 and 60%, respectively, and enzyme production. These effects are usually transient, e.g. removal of an antagonist is followed by complete recovery. Up- and down-regulation of gene expression, by mRNA and protein profiling has been demonstrated. VOCs have played an important role during the evolution of microorganisms in the context of their communities.

Bacteria↗
PubMed2003

Antimicrobial interactions of microbial species involved in the fermentation of cassava dough into agbelima with particular reference to the inhibitory effect of lactic acid bacteria on enteric pathogens.

Lactic acid bacteria, Bacillus species and yeasts are involved in the fermentation of cassava dough into agbelima. Microbial interactions within and between these groups of microorganisms were investigated in addition to the survival of five enteric pathogens inoculated into agbelima under various conditions. Nine out of 10 cultures of lactic acid bacteria isolated at the end of agbelima fermentation showed inhibitory effect against 10 cultures of lactic acid bacteria isolated at the start of fermentation. Only 3 out of 10 isolates of Bacillus subtilis were inhibited by 10 isolates of lactic acid bacteria tested. No interactions were observed between yeasts and the lactic acid bacteria, whereas three of the Bacillus isolates showed inhibitory effects against the yeasts. Twelve isolates of Lactobacillus plantarum tested inhibited the growth of an isolate each of Lactobacillus fermentum and Lactobacillus brevis but none tested positive for bacteriocin production. The antimicrobial effect of the lactic acid bacteria was attributed to acid production. In fermenting cassava dough, enteric pathogens survived to different extents depending on pH and their sensitivity to acids. Vibrio cholerae C-230, Salmonella typhimurium 9 and Salmonella enteritidis 226 were not detectable in 10 g of sample after 4 h when inoculated into the 48-h fermented product, agbelima, whereas Shigella dysenteriae 2357T and Escherichia coli D2188 were detectable up to 8 h in the product.

Antibiosis↗
PubMedDate not supplied

[Bacterial interactions].

The review deals with specific features of interactions in microbial biocenoses. The subdivision of the mechanisms of microbial interactions in associations into direct and indirect ones is proposed. The formation of intercellular contacts and matrix belongs to one group of mechanisms, the second group includes the products of metabolism (changes in the physical and chemical composition of the medium, specific growth regulators) and secreted factors (antibacterial substances, pheromones and signal molecules, vitamins, specific mediators). The applied aspects of the knowledge of microbial interactions in the human body are presented.

Anti-Bacterial Agents↗
PubMed1999

Physico-chemistry of initial microbial adhesive interactions--its mechanisms and methods for study.

In this review, initial microbial adhesive interactions are divided into adhesion to substratum surfaces, coaggregation between microbial pairs and co-adhesion between sessile and planktonic microorganisms of different strains or species. The physico-chemical mechanisms underlying the adhesive interactions are described and a critical review is given of currently employed methods to study microbial adhesive interactions, with an emphasis on the use of the parallel plate flow chamber. Subsequently, for each of the three microbial adhesive interactions distinguished, the role of Lifshitz-van der Waals, acid-base and electrostatic interactions is described based on existing literature.

Bacterial Adhesion↗
PubMedDate not supplied

Human polymicrobial infections.

CONTEXT: Polymicrobial diseases, caused by combinations of viruses, bacteria, fungi, and parasites, are being recognised with increasing frequency. In these infections, the presence of one micro-organism generates a niche for other pathogenic micro-organisms to colonise, one micro-organism predisposes the host to colonisation by other micro-organisms, or two or more non-pathogenic micro-organisms together cause disease. STARTING POINT: Recently, Gili Regev-Yochay (JAMA 2004; 292: 716-20) and Debby Bogaert (Lancet 2004; 363: 1871-72), and their colleagues, suggested another interaction: microbial interference-the ability of Streptococcus pneumoniae carriage to protect against Staphylococcus aureus carriage, and the inverse effect of pneumococcal conjugate vaccination on the increased carriage of Staph aureus and Staph-aureus-related disease. Strep pneumoniae carriage protected against Staph aureus carriage, and the bacterial interference could be disrupted by vaccinating children with pneumococcal conjugate vaccines that reduced nasopharyngeal carriage of vaccine-type Strep pneumoniae. WHERE NEXT: The medical community is recognising the significance of polymicrobial diseases and the major types of microbial community interactions associated with human health and disease. Many traditional therapies are just starting to take into account the polymicrobial cause of diseases and the repercussions of treatment and prevention.

Antibiosis↗