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At least 55 records · Page 3Linked to original sources
PubMed2000

Microbial interactions with tributyltin compounds: detoxification, accumulation, and environmental fate.

While inorganic forms of tin are of relatively low toxicity towards microorganisms, the more lipid-soluble organotins can be highly toxic. Generally, trisubstituted (R3SnX) organotins are more toxic than di- (R2SnX2) and monosubstituted (RSnX3) compounds; the anion (X) apparently having little influence on toxicity. However, many microorganisms exhibit resistance to organotins, a phenomenon of relevance to the environmental cycling of organotins and also to novel biological methods of treatment. Organotin degradation can involve the sequential removal of organic moieties to yield less toxic derivatives, e.g. debutylation of tributyltin compounds to di- and monobutylins. Such degradation is known to take place in bacteria, algae and fungi, and this provides one route for detoxification. In addition, microorganisms are capable of accumulating tributyltin compounds, and this is another mechanism of removal from solution. The high lipid solubility of organotins ensures cell penetration and association with intracellular sites, while cell wall components also play an important role. Of the fungal wall components, melanin pigments are capable of TBT binding, and the addition of melanin to growing cultures can remove toxicity; melanised strains are also more sensitive than albino strains of the same species. To date, little attention has been paid to the biotechnological exploitation of these interactions for the degradation of tributyltin or its removal from solution. This paper describes some interactions of microorganisms (bacteria, cyanobacteria, microalgae, and fungi) with tributyltin compounds, with particular reference to toxicity, bioaccumulation and detoxification. Such processes should receive due consideration in any environmental management programme.

Absorption↗
PubMed1997

Microbial interactions with catheter material.

The use of central venous catheters to deliver parenteral nutrition therapy is often complicated by infection. The original source of these infections has been debated but it appears that organisms colonizing the skin or those contaminating the catheter hub are most often responsible. Before forming a biofilm, an organism must first successfully attach to a surface. To do this, microbes have evolved strategies that allow them to adhere to surfaces and evade forces that would favor their detachment. Once a biofilm is formed on a catheter, the organisms are relatively safe from a host immune response and antibiotics. In this review, what is known about these interactions is discussed.

Bacterial Infections↗
PubMed1999

Microbial interactions in the vaginal ecosystem, with emphasis on the pathogenesis of bacterial vaginosis.

During bacterial vaginosis (BV), populations of lactobacilli which are generally dominant in the vagina of overtly healthy women are replaced by other facultative and anaerobic microorganisms. Some Lactobacillus strains produce hydrogen peroxide and all produce lactic acid; however, the antagonistic role of these metabolites in vivo remains controversial. Positive interactions among BV-associated organisms may contribute to the pathogenesis of BV and its sequelae.

Antibiosis↗
PubMed2002

Fungal ABC transporters and microbial interactions in natural environments.

In natural environments, microorganisms are exposed to a wide variety of antibiotic compounds produced by competing organisms. Target organisms have evolved various mechanisms of natural resistance to these metabolites. In this study, the role of ATP-binding cassette (ABC) transporters in interactions between the plant-pathogenic fungus Botrytis cinerea and antibiotic-producing Pseudomonas bacteria was investigated in detail. We discovered that 2,4-diacetylphloroglucinol, phenazine-1-carboxylic acid and phenazine-1-carboxamide (PCN), broad-spectrum antibiotics produced by Pseudomonas spp., induced expression of several ABC transporter genes in B. cinerea. Phenazines strongly induced expression of BcatrB, and deltaBcatrB mutants were significantly more sensitive to these antibiotics than their parental strain. Treatment of B. cinerea germlings with PCN strongly affected the accumulation of [14C]fludioxonil, a phenylpyrrole fungicide known to be transported by BcatrB, indicating that phenazines also are transported by BcatrB. Pseudomonas strains producing phenazines displayed a stronger antagonistic activity in vitro toward ABcatrB mutants than to the parental B. cinerea strain. On tomato leaves, phenazine-producing Pseudomonas strains were significantly more effective in reducing gray mold symptoms incited by a ABcatrB mutant than by the parental strain. We conclude that the ABC transporter BcatrB provides protection to B. cinerea in phenazine-mediated interactions with Pseudomonas spp. Collectively, these results indicate that fungal ABC transporters can play an important role in antibiotic-mediated interactions between bacteria and fungi in plant-associated environments. The implications of these findings for the implementation and sustainability of crop protection by antagonistic microorganisms are discussed.

ATP-Binding Cassette Transporters↗
PubMed2002

Innate immunity in host-microbial interactions: beyond B27 in the spondyloarthropathies.

The spondyloarthropathies are diseases influenced by genetic predisposition and, to a varying extent, infectious triggers. A causal role for bacterial infections is most clear for reactive arthritis. Recent insights into arthritogenic components of bacteria may set the stage for a better understanding of disease pathogenesis, the role of heat shock proteins in antigen processing and immune activation, and the adjuvant effect of CpG-DNA. Recent developments in the area of innate immunity broaden current concepts of genetically defined factors in host-pathogen interactions. In particular, the biology of toll-like receptors as important elements in the innate immune response to pathogens is being defined. These factors in innate immunity may have important implications for sequelae of infections, such as reactive arthritis.

Animals↗
PubMed1982

Microbial interactions in sediment communities.

Mineralization of organic matter in aquatic ecosystems with shallow waters occurs to a large extent in their sediments under anoxic conditions. This is achieved by a community of bacteria, which are the catalysts in a sequence of processes. Of the two possible terminal processes, methanogenesis and sulphate reduction, the first usually dominates in freshwater systems, whereas in estuarine and marine sediments electrons are mainly channelled to sulphate. Interactions between sulphate-reducing and methanogenic bacteria are described. Sulphate-reducing bacteria also show interactions with fermentative bacteria. After a brief description of properties of sulphate-reducing and fermentative bacteria occurring in sediments, examples are given of interactions between them. This is followed by the presentation of some results obtained from studies on competition for L-lactate between organisms belonging to both groups. It is shown that sulphate-reducing bacteria could successfully compete for L-lactate when this was available in growth-limiting amounts with sufficient sulphate and iron. Finally, a brief discussion is given of ecological niches of sulphide-oxidizing bacteria thriving in the upper sediment layers.

Anaerobiosis↗
PubMed1982

The role of microbial interactions in infectious disease.

The occurrence of infectious disease is affected by interaction between microorganisms in three ways. The indigenous flora (commensal microorganisms) of some mucous surfaces provide one of the main protective mechanisms against infection by pathogens (disease-producing microbes). The commensal populations interfere with the establishment of pathogens on mucous membranes by evoking anaerobic conditions, by competing for space and nutrients and by producing inhibitors. How, at the beginning of successful infection, pathogens in relatively small numbers overcome this protective activity of the commensal population is unknown. Although not a general phenomenon, some pathogens exacerbate the effects of others. The best examples are the potentiation of bacterial infections by existing viral infections: mucosal adherence and penetration by bacteria are enhanced and phagocytic defences against them weakened. Some microorganisms that are unable to produce significant disease on their own may combine with others to cause serious sickness. The harmful effects of these combinations of microorganisms can be explained by the multifactorial nature of pathogenicity (virulence), i.e. the capacity to produce disease. Although each member of the mixed population cannot alone produce the full complement of factors needed for disease production, the complement can be attained by combining contributions from different members.

Bacteria↗
PubMed2005

Birth-related increase in intracolonic hydrogen gas and nitric oxide as indicator of host-microbial interactions.

BACKGROUND: Bacterial colonization of the intestine early in life might have implications for allergy development. We studied early host-bacterial interactions in the gut by simultaneous measurements of hydrogen gas (H(2)) and faecal short chain fatty acid pattern (SCFAs), i.e. bacterial products, as well as of nitric oxide (NO), a marker of mucosal immune activation. METHODS: A novel minimally invasive technique was used for repeated measurements of luminal colonic H(2) and NO in 32 healthy newborn infants delivered vaginally or by Caesarean section. Luminal gas was sampled and analysed at five occasions: immediately after birth, day 1, days 3-5, 1 and 5-6 months after birth. RESULTS: Colonic H(2), NO and faecal SCFAs were undetectable at birth. The H(2) and SCFAs appeared within 24 h and continued to increase during the 6 months follow-up. Nitric oxide remained very low until 3-5 days after birth at which time it markedly increased. In some apparently healthy infants NO transiently reached levels similar to those seen in adults with inflammatory bowel disease. CONCLUSION: Intracolonic measurements of H(2) and NO may be useful to monitor the developmental colonization process as well as mucosal responses.

Aging↗