1. Preheat the oven to 400 degrees F.
2. In a bowl, combine the flours, wheat germ, baking soda and salt. Whisk to blend. Beat in the buttermilk and egg and stir just until moistened.
3. Turn the dough out onto a generously floured work surface and, with floured hands, gently knead it 8 to 10 times; the dough will be sticky. Gather into a loose ball.
4. On a non-stick baking sheet, form the dough into a 7" round. Dust the top of dough with a small amount of flour. Cut a 4" X into the top of the dough. Bake until the bread splits open at the X and makes a hollow sound when the underside is tapped (25-30 minutes).
5. Transfer to a wire rack and let cool for 2 hours before slicing.