Aerobic Plate Count
The aerobic plate count (APC) indicates the level of microorganisms in a product and is an estimation of the total viable aerobic bacteria present in a sample of raw material, in-process material, or finished product. Also refered to as the Standard Plate Count (SPC), it can be used to assess the overall bacterial load of a product.
Anaerobic Plate Count (AnPC)
This test is used to determine the total number of anaerobic bacteria (i.e., bacteria requiring no oxygen) present at mesophylic temperatures (30°C-37°C). Examples of such types of bacteria include Clostridium spp. Most human bacterial pathogens are facultative anaerobes and may show up on this test as well.
Sulfate reducing Bacteria
Sulfate reducing bacteria (SRB) are types of anaerobic bacteria that, as a part of their normal activities, generate hydrogen sulfide (H2S). This product can cause a number of significant problems. These range from "rotten egg" odors, through to the blackening of equipment, waters and slime formations, and the initiation of corrosive processes.
Acid Producing Bacteria (APB)
Some types of bacteria produce acidic metabolites, such as organic or inorganic acids. These bacteria are referred to as acid producing bacteria (APB). APBs can be a problem in gas transmission lines and could also be a problem in closed water systems that become anaerobic. The acids accelerate corrosion by dissolving oxides (the passive film) from the metal surface and accelerating the cathodic reaction rate. Examples of APBs include Thiobacillus thiooxidans which produce sulfuric acid and Clostridium aceticum which produces acetic acid.
Nitrifying Bacteria
Nitrifying bacteria recycle organic nitrogenous materials from ammonium (the endpoint for the decomposition of proteins) to nitrates. Their prescence can indicate that the water may have been polluted by nitrogen-rich organics from sources such as compromised septic tanks, sewage systems, industrial and hazardous waste sites and is undergoing an aerobic form of degradation.
Denitrifying bacteria
The presence of denitrifying bacteria can indicate that the water has been polluted by nitrogen-rich organics from sources such as compromised septic tanks, sewage systems, industrial and hazardous waste sites.
Iron bacteria are seen as nuisances, and are particularly common in systems using wells as a water source. Examples of iron bacteria include Gallionella, Sphaerotilus, Leptothrix, and Crenothrix. These aerobic, filamentous bacteria oxidize iron from a soluble ferrous (Fe2+) form to an insoluble ferric (Fe3+) form. They produce thick slime layers, which can cause blockage in a plumbing system. They can also discolour water (“red water”) or cause odors and odd taste. Iron bacteria test results include estimated CFU/ml.
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