In "bridge mode", the guest interface acts like it has its own
cable to the local network - just without having to use a
seperate cable.
This means if the host needs to use DHCP to get an IP address,
so should the guest.
From what you posted as the content of etc/network/interface
it looks like you have the guest on a different subnet than
the host.
To see what the interfaces are available and how there are set
us ifconfig
I'd try either changing the guest's the static IP address (how
it's currently set) to match the host's network - or change
the guest to use DHCP.