A simple mini-method to extract DNA directly from soil for use with polymerase chain reaction amplification.

A rapid, simple method is used that yields amplifiable fungal and bacterial DNAs directly from soil. DNA is separated from soil contaminants by electrophoresis in low-melting-temperature agarose and used directly in polymerase chain reaction amplification. Fifty 20-mg samples can be processed in one day. Fragments of 16S and 18S ribosomal RNAs are amplified by polymerase chain reaction with DNA extracted from the soil. Universal primers are used that are capable of amplifying ribosomal DNA from a wide variety of bacteria and fungi. Eubacterial and fungal primers are used that are capable of distinguishing between eubacterial and fungal DNAs. Restriction enzyme digests are performed on amplified DNA fragments from five soil samples.