I am planning to extract DNA with QIAamp Mini DNA extraction kit (Qiagen) from DNA Shield microbiome preserved samples. My samples contain small amount of cell, so my goal is to reduce the loss of cells by extracting DNA from the maximum amount of sample possible. QIAamp Mini kit recommend using a maximum of 200ul of liquid sample for the extraction, but I contacted the company and they told me I can increase it until 400ul if keep the proportions by doubling the volume of the kit reagents and pass all the liquid through the membrane in two centrifugation steps.
Taking into account DNAShield help in lysis cells and inactivate DNAses, could I skip some of the lysis buffers and proteinase K used in the first steps of the kit protocol by DNAshield and increase the volume of sample passed thought the silica membrane?