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#16S rDNA Sequencing and Analysis (Organism Identification)  Following the second dilution streaking, the organisms need to be identified. This is accomplished by Sanger sequencing of a 16S rDNA PCR product.  The samples can be prepared for 16S rDNA PCR via direct PCR (using the liquid culture as the template for the PCR reaction) or following DNA extraction. Direct PCR significantly decreases the amount of work needed for preparation, but it can yield poorer Sanger results, oth both  in terms of PCR success and resultant sequence quality. We recommend direct PCR when screening a large number of samples. DNA extraction can be used for any recalcitrant samples. DNA extraction is significantly more work, but it often generates better Sanger sequences allowing for more accurate identification. ##DNA Extraction  Depending on available equipment, experience, and cost there are a number of different options for DNA extraction. The use of Phenol-Chloroform followed by ethanol precipitation is a microbiology standard, and any number of protocols for this method can be found on the web. internet.  There are several advantages to using a commercially available kit for this purpose, notably ease and lack of harmful chemicals, but they typically are more expensive and include reagents for at least 50 samples. Our lab uses the Promega-Wizard Genomic DNA Purification Kit or the MO BIO-Power Soil DNA Isolation Kit Follow the protocol or kit instructions provided by the manufacturer and then proceed to "PCR reaction" below.