Agilent genotypes for these strains list a cryptic Amy gene in the F' of some of their cloning strains; tech tells me its an alpha-amylase gene that mat have been a "side-product" of the plasmids construction - it is in the CM-marked F's and the Kan marked F' in XL10-Gold Kan. Just curious as to how/why it got there - there is a paper from 1990 using B. subtilis alpha-amylase in a shuttle vector for cloning inactivation - doi: 10.1016/0167-4781(90)90060-f.. 1990 Apr 6;1048(2-3):223-30.Biochim Biophys Acta Cloning and expression of raw-starch-digesting alpha-amylase gene from Bacillus circulans F-2 in Escherichia coli, but how/why it might make its way linked? to their Cm/Km gene markers is a mystery!

XL-10 Gold has the genotype Tetr Δ(mcrA)183 Δ(mcrCB-hsdSMR-mrr)173 endA1 supE44 thi-1 recA1 gyrA96 relA1 lac Hte [F´ proAB lacIqZΔM15 Tn10 (Tetr) Amy Camr]; or [F´ proAB

lacIqZΔM15 Tn10 (Tetr) Tn5 (Kanr) Amy] in XL10-Gold Kan.