Poly-3-hydroxybutyrate (PHB)-containing biomass produced by Alcaligenes eutrophus was disrupted by surfactant-chelate aqueous solution, and its kinetics was investigated. Under conditions of temperature 30-60 degreesC, surfactant concentration 0.0016-0.0028 g/g, chelate concentration 0.0012-0.0021 g/g, pH 13, biomass size 97-450 mum and time 0-15 min, biomass breakage was a two-stage process with very fast zero order surface reaction in the first 1 min and followed by a chemical reagent diffusion-controlled reaction in the ensuing 9 min. Both stages were affected by temperature, time and biomass size, but the second phase was also affected by chemical reagent concentration. The established models could be applied not only to predict biomass disruption, but also to improve the quality of recovered PHB. According to the obtained kinetic data, when PHB-containing biomass was disrupted first at 60 degreesC for 1 min and then at 40 degreesC for 9 min, the molecular weight of PHB was increased whereas its purity and recovery rate were not decreased compared with a constant temperature of 50 degreesC. (C) 2002 Elsevier Science Ltd. All rights reserved.