By: Ayser Ashour Khalaf, university of Kerbala, collage of education for pure science, Department of biology
Many studies about biofilm of microbes bacteria and fungi ,that considerd one of the most virulence factors which in turns increased resistant for antibiotics and the last consisderd very big problems now days. Therefore this article highlighted for understanding what is biofilm, how could be formed, the properties and risks of biofilm.
Biofilms are diverse surface-attached microbe groups, primarily made up of polysaccharide, secreted protein and extracellular DNAs, kept together in the self-produced polymer matrix.
Biofilms may be bound to or formed on the surface by gram positives and gram negatives alike. Biofilm forming in response to environmental stress is a dynamic mechanism Bacteria make up biofilms: Radiation from UV, Dryness, nutrients limitation, pH, Temperature , High amounts of salt, pressure , antimicrobial agents.
Five main stages on the development, in biofilm, of: (i) reversible surface-attachment process where bacteria are not attached specifically; (ii) irreversible attachment phase involving association of bacterial and surface cell using bacterial adhesives such as fimbria and lipopolysaccharide (LPS); (iii) resident bacterial cells are able to make) extracellular polymer substances; (iv) mature biofilms at the point of bacterial cells synthesis and release the signalling molecules to sense reciprocal involvement leading to production of micro-colony and biofilms maturation; and (v) stage of the departure of biofilms by the bacterial cells and the return to the index; (v) the dispersal phase in which biofilms leave and the bacterial cells return to individual planktonic lifestyles.
PROPERTIES OF BIOFILMS: biofilms increase antibiotic resistance, this the great importance area of public health. the resistance may be involved many reasons one of these is Bacterial growing on biofilm are highly resistant up to 1000 times more than planktonic cells due to physiological differences and because of dimensioned rates of mass transport of antimicrobial agents to the biofilm cells.
Biofilm is also characterized by protection from phagocytosis by unable phagocytes from engulf a bacterium growing in the extracellular polysaccharides matrix attached to a solid medium. additionally to the ability of bacteria embedded in biofilm resistance to immunological and nonspecific defence mechanisms of the body, the biofilms help gene transfer. Many factors influence the biofilm formation the most important one is known as Quorum sensing system and this system responsible of regulating the density of bacterial cells in biofilm and responsible of regulating the gene expression during biofilm production operation.
RISKS OF BIOFILMS: On nearly all surfaces, both natural and synthetic surfaces, bacteria can colonize and form biofilms, Chronic and nosocomial disorders,Fouling of industrial tubing,Grain spoilage, marine and milk pollution and ship hull fouling, Healthcare Issues (Establish surfaces like catheters on surgical devices,Heart pumps, rhyphemes, implants at the breast, contact lenses.and CSF shunts .Moreover, biofilm bacterias contribute to numerous life-threats and human diseases, such as CF, otitis medium, periodontitis, bacterial endocarditis (IE), chronic disease and osteomyelitis.
In plant, P. aeruginosa biofilm on the roots of Arabidopsis and Ocimum Basilicum (sweet basil). Food safety and food industry Biofilms account for nearly 60% of Outbreaks of foodstuffs Listeria monocytogenes, which can induce abortions in pregnant women and other complications for immunocompromised people, are the most common biofilm forming foodborne pathogens and spoilage species. 
control and prevention of biofilms: various techniques and approaches have been employed that interfere with bacterial attachment, bacterial communication systems (quorum sensing, QS), and biofilm matrix. Development of beneficial biofilms can be promoted through manipulation of adhesion surfaces, QS and environmental conditions.
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