This method also does not discriminate between viable and dead cells as in Petroff-Hausser method. Breed method is mainly used to assess the quality of milk by giving the number of bacteria and leucocytes in milk. Also, the sample needs to be free from debris and food extraction.

Moreover, the cells that own too small size is difficult to count. However, there is no different cells calculation for live and dead cells. There advantages of this method are quick and easy count of cells and cheap cost. Petroff-Hausser method is performed to calculate the total cell of microorganism in small sample by using the glass slides in square form with fixed volume as shown in figure 1 and 2.įigure 1.Petroff-Hausser counting chamberįigure 2.Petroff-Hausser counting chamber grid Generally, there are two types of direct microscopic counts such as Petroff-Hausser method and breed method. Direct microscopic counts are performed by placing a bacterial suspension in a counting chamber, and require the use of specialized slide called the Petroff-Hausser counting chamber. Because of above reasons, variety of methods had been developed for quantitative enumeration of microorganisms such as direct microscopic counts, electronic cell counters, chemical methods, spectrophotometric analysis and serial-dilution agar plate analysis. In addition, worldwide the numbers of microorganisms in a given sample are required to know in certain aspects such as dairy industries, water treatment, food manufactures, and importantly in investigation and study of diseases. Moreover, it is often important to know not only what kinds of microorganism are present in a given or obtained sample but also to know the number of microorganism in sample which is difficult to count under the naked eyes because of their small size. The size of microorganisms is about 1/10th the size of a typical human cell, and measured in the scale of one millionth of a meter known as micrometer. Introduction It is difficult to know and imagine the size of microorganisms, since they are too small to be seen under the naked eyes.

Serial dilution lab report microbiology