Final answer:
A non-centrifuge method for isolating bacteria and phages from soil samples includes allowing sedimentation followed by filtration, which serves to increase the overall purity of the sample by removing larger particulate matter and bacteria.
Step-by-step explanation:
A non-centrifuge method for isolating bacteria and phages from soil samples in phage hunting, as mentioned in the seaphages discovery guide, is to allow the sample to sit until particulate matter settles and then use filtration. This process is often referred to as sedimentation, which is a non-mechanical method to separate components based on density, followed by filtration to further purify the sample. Sedimentation allows the heavier particles in the suspension to settle naturally at the bottom of the container due to gravitational forces. Once the sedimentation process is completed, the supernatant, which contains the phages and lighter particles, can be collected and passed through a filter with pore sizes small enough to trap bacteria but allow phages to pass through.
The primary purpose of filtration in this method is to increase the overall purity of the sample. Filtration will separate larger particulate matter and bacteria, essentially providing a cleaner phage solution for further analysis or application. Specifically, high-efficiency particulate air (HEPA) filters can be used to capture bacterial cells, endospores, and many viruses, thereby nearly sterilizing the air or fluid passing through these filters. The detailed and manual approach of allowing natural sedimentation followed by filtration provides an effective and alternative method to centrifuges, which use high centripetal acceleration to separate specimens of different densities.