A new PROMICON study on the simultaneous production of poly(3-hydroxybutyrate) (PHB) and exopolysaccharides (EPS) in cyanobacteria-rich microbiomes

A new PROMICON study explores the simultaneous production of poly(3-hydroxybutyrate) (PHB) and exopolysaccharides (EPS) in cyanobacteria-rich microbiomes, presenting new opportunities for sustainable biopolymer production. This research, led by Dr Beatriz Altamira Algarra during her scientific exchange at Faculdade de Ciências e Tecnologia da Universidade NOVA de Lisboa in 2023, was co-authored by Joan García, Cristiana A.V. Torres, Maria A.M. Reis, and Eva Gonzalez-Flo.

The study explores the potential of cyanobacteria to produce both PHB, a biodegradable plastic, and EPS, a versatile biopolymer used in various industries. Seven microbiomes rich in cyanobacteria were evaluated for their ability to produce EPS, with salinity and acetate concentration considered as influencing factors. However, despite expectations, neither acetate nor salinity significantly altered the EPS production rate, which ranged from 25 to 150 mg·L-1. Interestingly, glucose was found to be the dominant monosaccharide in the produced EPS.

In a 3L photobioreactor, the team achieved a remarkable dual biopolymer production, with EPS reaching 205 mg·L-1 and PHB 87 mg·L-1. Furthermore, the presence of uronic acid in the EPS aided biomass flocculation, streamlining the separation process and potentially reducing time and costs associated with production. The results show that cyanobacterial microbiomes can consistently produce EPS, even under changing environmental conditions, contributing to a more sustainable approach for biopolymer production.