Bioprocess Engineering Aspects of Biopolymer Production by the CyanobacteriumSpirulinaStrain LEB 18

Abstract

Microbial biopolymers can replace environmentally damaging plastics derived from petrochemicals. We investigated biopolymer synthesis by the cyanobacteriumSpirulinastrain LEB 18. Autotrophic culture used unmodified Zarrouk medium or modified Zarrouk medium in which the NaNO3content was reduced to 0.25 g L−1and the NaHCO3content reduced to 8.4 g L−1or increased to 25.2 g L−1. Heterotrophic culture used modified Zarrouk medium containing 0.25 g L−1NaNO3with the NaHCO3replaced by 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1of glucose (C6H12O6) or sodium acetate (CH3COONa). Mixotrophic culture used modified Zarrouk medium containing 0.25 g L−1NaNO3plus 16.8 g L−1NaHCO3with the addition of 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1of glucose or sodium acetate. The highest biopolymer yield was 44% when LEB 18 was growing autotrophically in media containing 0.25 g L−1NaNO3and 8.4 g L−1NaHCO3.