In theory, the direct cell cou

a) Both methods do not yield same result.The number of coloniesin the Direct Cell Count Plate would be higher most probably.It may vary according to the test conditions in the Heterotrophicplate count.b)Direct counting methods are used to determine bacterialconcentration without the need for advanced equipment.Direct counting methods include microscopic counts using ahemocytometer or a counting chamber. The hemocytometer works bycreating a volumetric grid divided into differently sized cubes foraccurately counting the number of particles in a cube andcalculating the concentration of the entire sample.As with hemocytometers or counting chambers, cultures need to beheavily diluted prior to plating. Otherwise, instead of obtainingsingle colonies that can be counted, of thousands of colonies willform, all lying atop of each other.Due to heavy dilution we get maximum number of singlecoloniesThe heterotrophic plate count (HPC), formerly known as the standardplateColonies may arise from pairs, chains, clusters, or single cellsall of which are included in the term colony-forming units(CFU).So the number colonies might not be exact always in Heterotrophicplate count.HPC test methods involve a wide variety of test conditions thatlead to a wide range of quantitative and qualitative results.Temperatures employed range from around 20 °C to 40 °C, incubationtimes from a few hours to seven days or a few weeks, and nutrientconditions fromlow to high. The test itself does not specify the organisms thatare detected.The count of colonies depend on these test conditions.So Total Heterotrophic Plate count does not provide actual countbut its count can be used as an indicator.