TY - JOUR
T1 - A circular bioprocess application of algal-based substrate for Bacillus subtilis natto production of γ-PGA
AU - Parati, Mattia
AU - Philip, Catherine
AU - Mendrek, Barbara
AU - Townrow, David
AU - Khalil, Ibrahim
AU - Tchuenbou-Magaia, Fideline
AU - Stanley, Michele
AU - Kowalczuk, Marek
AU - Adamus, Grazyna
AU - Radecka, Iza
N1 - © 2023 Parati, Philip, Mendrek, Townrow, Khalil, Tchuenbou-Magaia, Stanley, Kowalczuk, Adamus and Radecka. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).
PY - 2023/4/20
Y1 - 2023/4/20
N2 - Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, hydrating, non-immunogenic polymer. Bacillus subtilis natto is a wild-type γ-PGA producer originally isolated from Japanese fermented natto beans whose activity has been shown to be enhanced through ion-specific activation of Extrachromosomal DNA maintenance mechanisms. Being a GRAS γ-PGA producer, this microorganism has attracted great interest in its use within an industrial context. Here we successfully synthesised amorphous, crystalline and semi-crystalline γ-PGA between 11–27 g/L. In line with circular economy principles, scalable macroalgal biomass has been evaluated as substrate for γ-PGA, displaying great potential in both yields and material composition. In this study whole cell, freeze dried seaweed -namely Laminaria digitata, Saccharina latissima and Alaria esculenta-were pre-treated by means of mechanical methods, sterilised and subsequently inoculated with B. subtilis natto. High shear mixing was found to be the most suitable pre-treatment technique. Supplemented L. digitata (9.1 g/L), S. latissima (10.2 g/L), A. esculenta (13 g/L) displayed γ-PGA yields comparable to those of standard GS media (14.4 g/L). Greatest yields of pure γ-PGA were obtained during the month of June for L. digitata (Avg. 4.76 g/L) comparable to those obtained with GS media (7.0 g/L). Further, pre-treated S. latissima and L. digitata complex media enabled for high molar mass (4,500 kDa) γ-PGA biosynthesis at 8.6 and 8.7 g/L respectively. Compared to standard GS media, algal derived γ-PGA displayed significantly higher molar masses. Further studies will be necessary to further evaluate the impact of varying ash contents upon the stereochemical properties and modify the properties of algal media based γ-PGA with the aid of key nutrients; however, the material synthesised to date can directly displace a number of fossil fuel derived chemicals in drug delivery applications, cosmetics, bioremediation, wastewater treatment, flocculation and as cryoprotectants.
AB - Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, hydrating, non-immunogenic polymer. Bacillus subtilis natto is a wild-type γ-PGA producer originally isolated from Japanese fermented natto beans whose activity has been shown to be enhanced through ion-specific activation of Extrachromosomal DNA maintenance mechanisms. Being a GRAS γ-PGA producer, this microorganism has attracted great interest in its use within an industrial context. Here we successfully synthesised amorphous, crystalline and semi-crystalline γ-PGA between 11–27 g/L. In line with circular economy principles, scalable macroalgal biomass has been evaluated as substrate for γ-PGA, displaying great potential in both yields and material composition. In this study whole cell, freeze dried seaweed -namely Laminaria digitata, Saccharina latissima and Alaria esculenta-were pre-treated by means of mechanical methods, sterilised and subsequently inoculated with B. subtilis natto. High shear mixing was found to be the most suitable pre-treatment technique. Supplemented L. digitata (9.1 g/L), S. latissima (10.2 g/L), A. esculenta (13 g/L) displayed γ-PGA yields comparable to those of standard GS media (14.4 g/L). Greatest yields of pure γ-PGA were obtained during the month of June for L. digitata (Avg. 4.76 g/L) comparable to those obtained with GS media (7.0 g/L). Further, pre-treated S. latissima and L. digitata complex media enabled for high molar mass (4,500 kDa) γ-PGA biosynthesis at 8.6 and 8.7 g/L respectively. Compared to standard GS media, algal derived γ-PGA displayed significantly higher molar masses. Further studies will be necessary to further evaluate the impact of varying ash contents upon the stereochemical properties and modify the properties of algal media based γ-PGA with the aid of key nutrients; however, the material synthesised to date can directly displace a number of fossil fuel derived chemicals in drug delivery applications, cosmetics, bioremediation, wastewater treatment, flocculation and as cryoprotectants.
KW - ɣ-PGA
KW - circular bioprocesses
KW - industrial up-scaling
KW - macro-algal biomass
KW - GRAS
U2 - 10.3389/fchem.2023.1158147
DO - 10.3389/fchem.2023.1158147
M3 - Article
SN - 2296-2646
JO - Frontiers in Chemistry
JF - Frontiers in Chemistry
M1 - 2023.1158147
ER -
