  We discuss how the presence of gauge sub-systems in the Bacon-Shor code [D.
Bacon, Phys. Rev. A 73, 012340 (2006)] leads to remarkably simple and efficient
methods for fault-tolerant error correction (FTEC). Most notably, FTEC does not
require entangled ancillary states and it can be implemented with
nearest-neighbor two-qubit measurements. By using these methods, we prove a
lower bound on the quantum accuracy threshold, 1.94 \times 10^{-4} for
adversarial stochastic noise, that improves previous lower bounds by nearly an
order of magnitude.
