Alcaligenes latus, a producer of the intracellular bioplastic poly(P-hydroxybutyric acid), was disrupted by chemical and mechanical means. Chemical lysis employed sequential treatment with sodium dodecyl sulfate (SDS) and sodium hypochlorite. The SDS treatment alone never released more than 60% of the cellular protein (a measure of disruption), but more than 90% of the protein could be released by the two-stage chemical process. Mechanical disruption used a continuous flow bead mill, or a high-pressure homogenizer. Bead mill disruption obeyed first-order kinetics. The diameter of grinding beads did not affect the disruption rate, but protein release improved with increasing bead loading. At low biomass concentrations the homogenizer was ineffective for disruption, but the bead mill could release almost all available protein. Disruption in the mill was independent of the slurry biomass concentration, but the performance of the homogenizer improved with increasing concentration until concentration-related blockages made operation impractical.