Production of polyhydroxybutyrate (PHB) in Scenedesmus acutus using a low-cost substrate

The importance of conventional plastics is undeniable; however, their non-biodegradability makes them one of the biggest environmental problems. Among the alternatives to mitigate environmental damages, the production of polyhydroxyalkanoates (PHB) provides a biodegradable solution, making them accessible to a wide variety of applications. In general, biopolymers accumulate as energy and carbon storage material in microorganisms such as bacteria and microalgae. In the present study, the impact of different sources like carbon, glucose, nitrogen and sodium was tested on the production of PHB in the cultures of the microalgae Scenedesmus acutus. To evaluate the effect of the variables, a fractional Taguchi experimental design was devised and executed, thus, 16 experimental runs and 3 replicas in each treatment were considered. Results showed calculated concentrations of the biopolymer in a range from 7.5 to 24.7% w/w of dry weight. Additionally, the PHB was identified by spectroscopic and thermogravimetric analysis. Statistical analysis was performed, showing differences in biomass production, PHB concentration in g L^- 1 and the percentage of PHB. Likewise, a Pareto diagram was used to consider the biomass production results, with glucose, biomass-glucose, and biomass-sodium as determining factors in the PHB production. The present research provides significant data on critical factors related with PHB production, to the best of our knowledge, thus showing S. acutus may be a promising candidate among PHB producers through a low-cost means.