  We introduce a new Kondo ladder model by coupling the well-known
Takhtajan-Babujan S=1 chain to a half-filled one-dimensional electron gas, and
we solve it using quantum field theory techniques. Through the so-called
underscreened Kondo effect, this gives novel insights into low-dimensional spin
liquid systems. For instance, the optical conductivity reveals only a pseudogap
at $k=\pi$ despite of the insulating state, a coherent magnon peak in the
dynamical spin susceptibility coexists with an incoherent spinon background,
the magnetization yields a fractional-like quantization. More generally, this
problem belongs to the class of Luttinger liquids in active environments, a
topic of importance not only to the Kondo physics, but also to striped phases
or carbon nanotubes. Experimental consequences on heavy-fermion systems are
also discussed.
