Exploring Serial Dilution and Plating in Microbiology Experiment 8.1
Is the following statement true or false?
Serial dilution and plating worksheet for experiment 8.1. a) True b) False, Final answer:
Answer:
Serial dilution is a microbiological technique used to decrease the concentration of a sample in a step-wise manner for accurate counting of bacteria using the pour plate or spread plate method. For dilute samples, a concentration step may involve membrane filtration. The exact true or false statements pertaining to experiment 8.1 are not provided in the context and cannot be addressed specifically.
Understanding Serial Dilution Technique
Serial dilution is a laboratory technique used in microbiology to create a series of dilutions that decrease the concentration of a sample solution by a known amount each time. This method is essential for quantifying the number of organisms, such as bacteria, in a sample, and is typically followed by the plate counting method using either the pour plate or the spread plate technique to estimate the number of colony-forming units (CFUs). During a serial dilution, a fixed volume (for example, 1.0 mL) of a culture is mixed with a larger volume of dilution solution (e.g., 9.0 mL of sterile broth), achieving a dilution factor of 10, or 1:10. Subsequent dilutions are made to achieve 1:100, 1:1000, and so on. This process helps in obtaining plates with CFUs within a countable range, ideally 30 to 300, to ensure accurate counting and reliable results.
Role of Membrane Filtration in Concentration Step
For very dilute samples, such as drinking water, a concentration step might be required, typically involving membrane filtration. The sample's organisms are trapped by a membrane filter and transferred to a Petri plate with a growth medium for further incubation and counting. The aim is always to have a viable cell count that is both accurate and representative of the original sample.
Worksheet Statements for Experiment 8.1
Regarding the statements in the worksheet for experiment 8.1, without the context it is unclear what particular aspects are being referred to as true or false. The spread plate method and the pour plate method are indeed established techniques for plating diluted bacterial cultures to count CFUs.