Since the evolution of universe,microbes are the first life form originated on the earth- the primitives.They survive in various forms.They can be useful or harmful.Some of them form a film like structure known as THE BIOFILM. In an industry if the dirt from a pipe or instrument is not removed then it will result in accumulation of microbes hence the formation of the biofilm . The purpose of the biofilm formation is to protect the microbes and trap nutrition for the growth of the microbes. As we know bacteria ,a prokaryotic microorganism can survive as a individual cell or form groups popularly known as bacterial colonies which consist of microorganisms of same origin and sharing common characteristics .But biofilm is something different from the colonies. We can say it as a microbial union entrapped in an organic extracellular secretions,more technically in a matrix known as Extra cellular polymeric substance(EPS).
STRUCTURE OF THE BIOFILM
It is a microbial confinement attached to a surface or substratum . The extra cellular polymeric substance or usually the Polysaccharides facilitates sharing of genetic material between the constituting cells .There are some routes pres by means of which water , nutrients,oxygen enter into it and reaches the lower region of biofilm. The same pathway also serve for removal of excreted materials to the surface.The transportation takes place by passive and facilitated diffusion.The most wonderful thing about it is that both aerobes and anaerobes share common habitat due to interrupted oxygen diffusion and availability of low oxygen concentration.
HOW EPS IS BENEFICIAL FOR THE MICROBES?
The extracellular polymeric substance provides a friendly surrounding for the microbial life.It protects them from the harsh environment such as adverse environment and anti microbial. It enables them to have access to their nutrient requirements.
The cells in biofilm communicate to each other through production of some chemical signal inducers and this phenomena is known as Quorum sensing. It refers to a gene controlling mechanism which needs to be modified when there is a change in density of constituting cells and to carry out this function a chemical known as auto inducer is released from the cells which act as a indicator for making necessary changes in gene expression and accordingly cell number.The extracellular material and the extensions present on the cell wall of bacterial together form a strong adherence on the surface by bringing about changes in surface charge and free energy by electrostatic and covalent bonds. As long as the microbes get their nutrients they remain intact to the surface but when they are deprived of nutrients they start detaching from the surface and there is significant decrease in their size.However they can regain their size when nutrient is made available to them. Other factors such as pH,temperature, cell structure,ionic concentration,constituents of extracellular polysaccharide also affects the growth of microbes.
MICROBES CAPABLE OF PRODUCING BIOFILM
Psuedomonas , Enterobacterium , Flavobacterium , Staphylococcus , Bacillus, L. monocytogens , Salmonella etc.
BIOFILM-IN FOOD SECTOR.
The Biofilm is comprised of pathogenic life forms which cause spoilage in food by accumulation of toxic substances in food making it inappropriate for consumption.These affect many of our organs and cells and results in fatality.In our life food is a primary concern and it can be a gate way of several monstrous ailments.Basically biofilm formation is a surface phenomena.So it is more prevalent on apparatus and equipment used in food industry. All the apparatus and equipment used in food industry come in direct contact with food during processing and manufacturing and this intimacy creates chances of contamination of food by the microbes already present on the surfaces. Biofilm formation reduces the cross sectional area and affect the flow rate through pipes.
Sometimes some microbes detach from the surface and with the flow they move to other regions where they start forming biofilms. We cant say that a food is completely devoid of microorganisms without close observation.The pathogens remain intact in the food and reduce its shelf life and its consumption may lead to food borne diseases.The cells present in the biofilm are not sensitive to thermal treatment and they are not easily encountered by thermal processing such as by cooking. Biofilms act as a barrier to heat conduction and there is improper thermal processing of the concerned food.These cause erosion and damage to the part of the apparatus where they are localized and show corrosion. As the cells are covered by a thick polysaccharide layer,the sanitizer or chemicals used dont come in direct contact with them hence they remain unaffected.
DETECTION OF BIOFILMS
Colored spectrum of surface of steel wares ,mucilaginous or viscous feel , polysaccharide layer detection by ATP bioluminescence apparatus.
SELECTION CRITERIA OF DEVICES AND APPARATUS TO MINIMIZE THE CHANCES OF BIOFILM FORMATION
Biofilm can be formed by pathogenic microbes which may be proved as hazardous for human beings.These are mainly known to cause many infectious disease primarily device related ailments. Biofilms commonly occur in bend,curves,joints of devices which are not easily prominent. It is very difficult to remove them by normal cleaning process or by prophylaxis . Surface characteristics such as roughness helps in the biofilm formation.It is more prevalent on rough surfaces.The roughness is measured by R factor ,which should be very less from safety point of view. There are some limits of R factor which decides the purchase of devices and various apparatus up to allowed degree of roughness.
ERADICATION OF BIOFILM
Nothing is impossibles in this modern tech world.So removal of biofilm is possible by various ways. It is all about the sanitary techniques used.The biofilms can be removed easily if cleaning measures are taken earlier. These can be removes mechanical processes such as vacuum cleaning,using scrubbers, brushes and other cleaning tools.These methods are quite easier if the biofilm is at its initial stage which require cleaning in place (CIP) system for instant action. Otherwise if it has developed to its best then we have to go for chemical treatments such as use of detergents.Detergents carry away the covering substances and when the cells get exposed to disinfectants they start deteriorating.According to a observation cleaning in 8 hours interval may cause permanent deletion of biofilm formation.
CURRENT RESEARCH CONSEQUENCES
According to a study conducted by U.S.D.A ,a strong negative electrostatic charge can be helpful in preventing biofilm formation and it has been tested in Meat Quality Research Unit. Such strong negative charge can be achieved by various techniques such as treatment of steel with a electrified acid solution or by electro-polishing which will completely remove the chances of biofilm formation.There can be evolution in techniques regarding eradication of biofilms.
Unless until we have a safer and worth applicable method we should rely on mechanical and chemical methods.In order to maintain the longevity of equipment and safety standard of processed food, we should prefer a frequent cleaning at a suitable time interval.Food industries should follow the safety concerns in order to minimize the expenses and to provide an uninterrupted supply of hygienic and friendly food.
Here is a visual depiction of the detailing of BIOFILM . See the video below,