There are several sources for single strand nucleases.  The first widely used enzyme was mung bean nuclease, but this nuclease has been shown to have high non-specific activity, and only works at low pH, which can degrade PCR products and dye-labeled primers.  The original source for single strand nuclease was from CEL1, or CJE (celery juice extract), but other products have entered the market including Frontier Genomics’ SNiPerase enzymes, which have been optimized for use on platforms that use labeled and unlabeled PCR products (see next section).  Transgenomic isolated the single strand nuclease protein and sells it as a recombinant form.  The advantage of the recombinant form is that unlike the enzyme mixtures, it does not contain non-specific nuclease activity, which can degrade the dyes on the PCR primers.  The disadvantage is a substantially higher cost.