Implication of organic solvents in the precipitation of ?-polyglutamic acid for application as a sustainable flocculating agent

Author(s)

Fernandes, Ana Rosa Aon Cardoso ; Sganzerla, William Gustavo ; Granado, Nilton Pereira Alves ; Campos, Valquiria

• Document type: Journal article
• Source: BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY; v. 50, p. 9-pg., 2023-07-01.

Abstract

& gamma;-Polyglutamic (& gamma;-PGA) acid is a homopolyamide composed of D-and l-glutamic acid units. It is an anionic biopolymer that has properties such as water solubility, non-toxicity, and biodegrad-ability. & gamma;-PGA, has many environmental applications, including use as an increment to the floccu-lation process in water treatment. This study evaluated the extraction and quantification of & gamma;-PGA using different organic solvents, following by application as a sustainable flocculating agent. The results demonstrate that the use of methanol was able to precipitate 6.83 mg & gamma;-PGA g-1 natto, followed by 5.44 and 4.24 mg & gamma;-PGA g-1 natto, respectively for ethanol and acetone. The adoption of refrigeration (12 h) is an advantage to increase the yield of the biopolymer for methanol (46.27%), ethanol (52.25%), and acetone (14.25%) as a precipitating agent. The & gamma;-PGA yield increased in overnight extraction with ethanol, enabling the use of ethanol as an alternative to methanol. Due to steric stabilization, it was observed that increasing the & gamma;-PGA concentration resulted in a reduction in the flocculation rate. The highest flocculation rate (92.9%) was achieved at 10 mg L-1 of & gamma;-PGA extracted with methanol, followed by acetone at 10 mg L-1 of & gamma;-PGA (92.43%) and ethanol at 5 mg L-1 of & gamma;-PGA (92.2%). (AU)

• FAPESP's process: 15/02650-8 - Production and environmental application of y-polyglutamic acid by cultivation of B. subtilis in soy substrate
• Grantee: Valquiria de Campos
• Support Opportunities: Regular Research Grants