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Biofilm of Salmonella
June 21, 2004Advances in the study of the salmonella bacteria, being undertaken at the Pamplona Institute of Agrobiotechnology and Natural Resources and led by professor I'±igo Lasa Uzcudun of the Public University of Navarre, have been recognised in the principal international magazine in the field of Microbiology, Molecular Microbiology, at a congress held recently in the German city of Heidelberg.
The Navarre researchers are analysing the role that a new family of Salmonella typhimurium proteins play in the biosynthesis of cellulose and in the formation of the biofilm of the salmonella bacteria.
Biofilms
The presence of biofilms is commonplace in nature. Who has not seen the mucous material on the inside of a vase after we have had flowers there some time, the slimy substance covering stones on riverbeds ... these are biofilms. The capacity for biofilm formation does not appear to be restricted to any one specific group of micro-organisms and, nowadays, it is believed that, if the environmental conditions are right, all micro-organisms are able to form biofilms.
Although the composition of biofilm is variable depending on the system under study, in general the main component of biofilm is water - as much as 97% of the total content. Apart from water and the bacterian cells, the biofilm matrix is a complex formed principally by exopolysacharrides.
Bacterian and infectious biofilms
Currently, with chronic infections such as those related to medical implants or other chronic conditions such as otitis media, pneumonia or chronic urinary infections, amongst others, direct analysis of the infected implants and tissues clearly show that the bacteria responsible for the infection grows adhering to the tissue or implant, producing biofilms.
The bacteria are protected, inside the biofilm, from the action of antibodies from attack by phagocytic cells and from antimicrobian treatment. Thus, they do not respond suitably to antibiotic treatament and produce recurrent episodes with the result that, in most cases, the only solution is the substitution of an implant. This is because the bacterias in the biofilm can be up to 1000 times more resistant to antibiotics than these same bacteria grown in a liquid medium.
In the last five years, many research groups have directed their efforts to identifying the genes responsible for the formation of the biofilms and those genes required to maintain the structure of the biofilm. In order to identify these genes, there has been a recent development in genomics and proteomics that has resulted in many of these groups are using microarrays or proteomic techniques for identifying the genes that express themselves in a different way in biofilm conditions or planktonic conditions, even though we are dealing with the same bacteria. Amongst these genes, a great proportion of genes are repeatedly found the function of which is unknown, which points to the existence of genes specific to the biofilm lifestyle and the phenotype of which has not been possible to visualise to date.
It is precisely on the Salmonella and Staphylococcus bacteria that Professor Lasa Uzkudun's research group has been carrying studies. They have discovered a new family of proteins related to the formation of biofilms and which have been unidentified to date. This group of proteins may well explain the mechanism of the biofilm when colonising new surfaces, the method of adhering to different media, the regulation of the process of biofilm formation, etc., given that some of the discovered proteins have a precursor function in the formation of the biofilm.
Finally, it would appear logical that the formation of the biofilm be produced in response to the ambient conditions and so exist systems that transmit the signal for the surrounding environment to the interior of the bacteria in order to suit the expression of the genes to the new environment. Even so, despite all that has been learned in recent years about bacterian biofilms, what is the "Biofilm" phenotype still remains to be defined exactly. Only then can it be determined what are the physiological changes which take place therein and what are the genetic requirements and regulation mechanisms of such a process.
Elhuyar Fundazioa
The presence of biofilms is commonplace in nature. Who has not seen the mucous material on the inside of a vase after we have had flowers there some time, the slimy substance covering stones on riverbeds ... these are biofilms. The capacity for biofilm formation does not appear to be restricted to any one specific group of micro-organisms and, nowadays, it is believed that, if the environmental conditions are right, all micro-organisms are able to form biofilms.
Although the composition of biofilm is variable depending on the system under study, in general the main component of biofilm is water - as much as 97% of the total content. Apart from water and the bacterian cells, the biofilm matrix is a complex formed principally by exopolysacharrides.
Bacterian and infectious biofilms
Currently, with chronic infections such as those related to medical implants or other chronic conditions such as otitis media, pneumonia or chronic urinary infections, amongst others, direct analysis of the infected implants and tissues clearly show that the bacteria responsible for the infection grows adhering to the tissue or implant, producing biofilms.
The bacteria are protected, inside the biofilm, from the action of antibodies from attack by phagocytic cells and from antimicrobian treatment. Thus, they do not respond suitably to antibiotic treatament and produce recurrent episodes with the result that, in most cases, the only solution is the substitution of an implant. This is because the bacterias in the biofilm can be up to 1000 times more resistant to antibiotics than these same bacteria grown in a liquid medium.
In the last five years, many research groups have directed their efforts to identifying the genes responsible for the formation of the biofilms and those genes required to maintain the structure of the biofilm. In order to identify these genes, there has been a recent development in genomics and proteomics that has resulted in many of these groups are using microarrays or proteomic techniques for identifying the genes that express themselves in a different way in biofilm conditions or planktonic conditions, even though we are dealing with the same bacteria. Amongst these genes, a great proportion of genes are repeatedly found the function of which is unknown, which points to the existence of genes specific to the biofilm lifestyle and the phenotype of which has not been possible to visualise to date.
It is precisely on the Salmonella and Staphylococcus bacteria that Professor Lasa Uzkudun's research group has been carrying studies. They have discovered a new family of proteins related to the formation of biofilms and which have been unidentified to date. This group of proteins may well explain the mechanism of the biofilm when colonising new surfaces, the method of adhering to different media, the regulation of the process of biofilm formation, etc., given that some of the discovered proteins have a precursor function in the formation of the biofilm.
Finally, it would appear logical that the formation of the biofilm be produced in response to the ambient conditions and so exist systems that transmit the signal for the surrounding environment to the interior of the bacteria in order to suit the expression of the genes to the new environment. Even so, despite all that has been learned in recent years about bacterian biofilms, what is the "Biofilm" phenotype still remains to be defined exactly. Only then can it be determined what are the physiological changes which take place therein and what are the genetic requirements and regulation mechanisms of such a process.
Elhuyar Fundazioa
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Exposure to both traffic, indoor pollutants puts some kids at higher risk for asthma later
New research presents strong evidence that the "synergistic" effect of early-life exposure to both outdoor traffic-related pollution and indoor endotoxin causes more harm to developing lungs than one or the other exposure alone.
New study finds MRSA on the rise in hospital outpatients
The community-associated strain of the deadly superbug MRSA-an infection-causing bacteria resistant to most common antibiotics-poses a far greater health threat than previously known and is making its way into hospitals, according to a study in the December issue of Emerging Infectious Diseases.
Researchers establish common seasonal pattern among bacterial communities in Arctic rivers
New research on bacterial communities throughout six large Arctic river ecosystems reveals predictable temporal patterns, suggesting that scientists could use these communities as markers for monitoring climate change in the polar regions.
Biologists discover bacterial defense mechanism against aggressive oxygen
Bacteria possess an ingenious mechanism for preventing oxygen from harming the building blocks of the cell.
Saving the single cysteine: new antioxidant system found
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Beyond sunlight: Explorers census 17,650 ocean species between edge of darkness and black abyss
Census of Marine Life scientists have inventoried an astonishing abundance, diversity and distribution of deep sea species that have never known sunlight - creatures that somehow manage a living in a frigid black world down to 5,000 meters (~3 miles) below the ocean waves.
Surface bacteria maintain skin's healthy balance
On the skin's surface, bacteria are abundant, diverse and constant, but inflammation is undesirable. Research at the University of California, San Diego School of Medicine now shows that the normal bacteria living on the skin surface trigger a pathway that prevents excessive inflammation after injury.
On the Trail of a Vaccine for Lyme Disease: Yale Researchers Target Tick Saliva
A protein found in the saliva of ticks helps protect mice from developing Lyme disease, Yale researchers have discovered. The findings, published in the November 19 issue of Cell Host & Microbe, may spur development of a new vaccine against infection from Lyme disease, which is spread through tick bites.
Cigarettes Harbor Many Bacteria Harmful to Human Health
Cigarettes are "widely contaminated" with bacteria, including some known to cause disease in people, concludes a new international study conducted by a University of Maryland environmental health researcher and microbial ecologists at the Ecole Centrale de Lyon in France.
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