Prawn & Fish Culture
WHAT ARE ENZYMES?
Enzymes are basically a class of protein which act as a hydrolytic organic catalyst to speed up various chemical and biochemical reactions without being changed themselves. Enzymes in biochemical reactions only act as organic catalysts. The enzymes actually becomes a part of the action, but after having caused it, split off from it and are themselves unchanged. This action first involves a coupling of the enzyme and substrate to give an enzyme-substrate complex. After the biochemical reactions are completed and products formed, the enzyme is released for catalyzing another reaction. Since enzymes are biochemically active compounds and may be principally made up of protein, they are sensitive to environment and are subject to the conditions that often affect proteins. Some enzymes are more stable than others. Traditionally those enzymes produced by the genus of bacteria known as Bacillus (which is comprised of rod shaped bacteria) are reasonably stable and are well suited for various types of aquaculture and industrial uses.
Enzymes are very useful and they are the essential building blocks of life. Non-biological catalysts like charcoal or platinum, often need extremes temperature and pH. However, enzymes must work in the mild conditions of a cell in the body, at approximately 40° C and at a pH between 6.5 and 7.5. All enzymes are sensitive in some degree to temperature. When moistened, temperatures in the 130° F (55° C) range or above for over 30 minutes will generally cause rapid degradation of many enzymes with a concurrent loss of activity. Although some enzymes contained in NS Series products are quite stable at temperatures even approaching boiling (212º F or I00° C), optimal temperatures for most hydrolytic enzymes produced are in the 104° F to 122° F or 40° C to 50° C range. Each 10° C below the optimal temperature generally reduces the effective activity of the enzyme by about 30%. Although less active at temperatures of 35 to 40° F (2 to 4° C) these enzymes will still act.
Naturally occurring microorganisms that have been isolated and adapted to produce large amounts of digestive enzymes when introduced into a waste stream. Microorganisms and their enzyme systems are responsible for the many different chemical reactions produced in the degrading of organic matter. As the bacteria metabolize, grow and divide, they produce enzymes. These enzymes are high molecular weight proteins. There are many types of enzymes, depending upon the almost innumerable reactions into which they enter.
As an organic catalyst, enzymes are produced by all living cells that act mainly by forming temporary chemical combinations with substrates. Chemicals changed by enzyme-catalyzed reactions are called the substrates of that enzyme, and they fit into the active site of the enzyme, where the reaction takes place, in a lock-and-key mechanism. The products of the reaction then leave the active site, freeing it up for more similar reactions to take place. Enzymes are high molecular weight proteins, highly specific and act rapidly and efficiently without themselves being altered. They are collectively grouped into two classes, namely:
Exoenzymes produced within, but elaborated outside the bacterial cell break down more complex organic material to a size that can pass through the cell wall and cell membrane. T he exoenzymes are active inside the cell wall and work within the cell to convert this material to products from which the cell grows and reproduces.
Enzymes are highly specific. They will not interact with just any substance. For example, the enzyme amylase will only act on carbohydrates converting it into simple sugar. Protease will act only on protein and nothing else. The theory behind the working is called the "lock and key" theory. The enzyme is shaped so that the products fit into them, react and are released. When compared with inorganic catalysts, enzymes are different in their rate of reaction and in their specificity, their ability to act selectively on a small group of chemically similar substances.
Enzymes contained in NS Series products include amylase, a starch digesting and liquefying enzyme which changes starchy substrates into simpler, more soluble sugars. The illustration shows how amylase cuts the molecular chains of carbohydrates (CH2O) and converts it into simple sugar in order for it to be converted as food for microorganisms. Amylase reduce the energy required for this to happen.
Amylase digests starch by catalyzing hydrolysis, which is splitting by the addition of a water molecule. Therefore starch plus water becomes maltose (which is equivalent to two joined glucose molecules). Other enzymes then further digest the maltose to glucose. Amylase is also called diastase and is found in both plants and animals. Other synonyms for specific types of amylase includes : alpha-amylase, beta-amylase, isoamylase, pullulanase, amyloglucosidase & glucoamylase. Amylase hydrolyzes starch, glycogen, and dextrin to form in all three instances glucose, maltose, and the limitdextrin. Amylase is the digestive enzyme needed to digest carbohydrates, one of the three major food groups needed for proper nutrition. If carbohydrates are not properly broken down before they are absorbed, serious health consequences can occur.
The lipases contained in NS Series products are of several types. These enzymes are of microbial and animal origin which gives the broadest spectrum of activity and effectiveness possible. These enzymes are effective on animal and vegetable fats and oils (not petroleum or mineral grease and oils). The products of the lipolytic action of these enzymes are water soluble or dispersible. They will not redeposit themselves on lines and tanks. Lipases, therefore, will help degrade animal, food or vegetable greases relieving build-ups or restrictions caused by these types of organic materials. Lipases are much more effective in digesting fats when the enzymes are combined with a surfactant (detergent or surface active agents). A surfactant helps to emulsify fats and oils. This means that these fats and oil are suspended in smaller micro globules, giving the greasy deposits much greater surface area and increasing the area of attack by the lipase. Some NS Series products are compounded with a biodegradable non-phosphate, relatively non-toxic surfactant added.
The aim is to produce the various enzymes which digest the organic fraction of the waste. Microbes do not chew up food. They must absorb it through their cell walls. Accordingly, they secrete enzymes to hydrolyze the food into small particles which then can be absorbed into the cell. This extracellular digestion is what breaks down the volume of organic waste. If this extracellular digestion is accomplished by enzymes, why not just add enzymes? Enzymes do not multiply and are quickly washed out of the system. Other than a temporary benefit, you are back to square one, unless you keep adding enzymes several times a day.
The rate of reaction may be increased by elevating the quality of the substrate or temperature up to a certain point. But beyond this, the rate of reaction ceases to increase because the enzyme concentration limits it.
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