In cultures of Azotobacter vinelandii inoculated using washed cells ( avoiding exhausted broth components) alginates of a higher molecular weight (1200 kDa) than those obtained in cultures conventionally inoculated ( 350 kDa), were produced. Also, when comparing conventionally inoculated cultures with those inoculated with washed-cells, the alginate lyase activity was delayed and the final polymer concentration decreased from 4.8 to 3.5 g l(-1). This suggests that components in the exhausted inoculum broth play important regulatory roles in alginate biosynthesis and needs to be taken into account when describing polymer biosynthesis.