Environmental DNA extracted from environment samples (water, soil, gut content, etc....) while extraction DNA from specific tissue you follow the conventional method as you said from liver or flesh and so on. Now if you are using kits, you follow the manufacturer manual you can get genomic DNA. If you used the manual procedure you should check solutions conc. and pH of the analytical solution. Also, the working solution of electrophoresis pH should check
Md Ramim Tanver Rahman I confused that more genomic DNA will be mixed up and it is also difficult to filter the solution to remove others except bacteria.