title: Influence of nutritional and physicochemical variables on PHB production from raw glycerol obtained from a Colombian biodiesel plant by a wild-type Bacillus megaterium strain.
abstract: Biodegradable polymers are currently viable alternatives to traditional synthetic polymers. For instance, polyhydroxybutyrate (PHB) is intracellularly produced and accumulated by Bacillus species, among others. This study reports several wild-type Bacillus strains with the ability to accumulate PHB using raw glycerol from biodiesel production as the sole carbon source. Out of 15 strains from different sources, B. megaterium B2 was selected as the most promising strain for further statistical optimization of the medium composition. Plackett-Burman and central composite designs were used to establish key variables and optimal culture conditions for PHB production using both 250-mL shake flasks and a 7.5-L bioreactor. Temperature and concentrations of glycerol and Na2HPO4 are the experimental variables with the most significant influence on PHB production by B2. After 14 hours of fermentation in shake flasks with optimized medium, B2 produced 0.43 g/L of PHB with a 34% accumulation in the cells. In contrast, under the same conditions, a maximum PHB concentration of 1.20 g/L in the bioreactor was reached at 11 hours. These values correspond to a 48% and 314% increase in PHB production compared to the initial culture conditions. These results suggest the potential of B2 as a PHB producer using raw glycerol, which is an inexpensive, abundant and readily available carbon source.
authors.affiliation: School of Chemical Engineering, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Paalo
authors.initials: P
authors.lastname: Moreno
authors.affiliation: School of Chemistry, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Camilo
authors.initials: C
authors.lastname: Yañez
authors.affiliation: Chemical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Nilo Sérgio Medeiros
authors.initials: NS
authors.lastname: Cardozo
authors.affiliation: School of Chemical Engineering, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Humberto
authors.initials: H
authors.lastname: Escalante
authors.affiliation: School of Chemistry, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Marianny Y
authors.initials: MY
authors.lastname: Combariza
authors.affiliation: School of Microbiology, Universidad Industrial de Santander, Bucaramanga, Colombia. Electronic address: caguzlun@uis.edu.co.
authors.forename: Carolina
authors.initials: C
authors.lastname: Guzman
mesh_terms: D001410:Bacillus megaterium / Q000145:classification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D056804:Biofuels / Q000382:microbiology*; D019149:Bioreactors / Q000382:microbiology; D005990:Glycerol / Q000302:isolation & purification / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000302:isolation & purification / Q000378:metabolism*; D007220:Industrial Waste / Q000517:prevention & control*; D009753:Nutritive Value / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D011091:Polyesters / Q000302:isolation & purification / Q000378:metabolism*; D013696:Temperature; D000094122:Polyhydroxybutyrates
chemical_list: D056804:Biofuels; D005990:Glycerol; D006885:Hydroxybutyrates; D007220:Industrial Waste; D010710:Phosphates; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C018279:sodium phosphate