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Abstract

Brazil is a country with a large production of residue from the sugar and ethanol industry, such as sugarcane bagasse, which over time can generate environmental impacts. Aiming to reduce these impacts, strategies are being developed with the purpose of utilizing the waste, among which is to use it as a substrate for the production of compounds with commercial value, such as citric acid (CA). Currently, most of the CA production is made by Aspergillus niger, belonging to the Aspergillus section Nigri, which is also found in Aspergillus welwitschiae, that has been standing out regarding the production of CA. In this context, this work had the objective of evaluating the production of CA by wild and mutant A. welwitschiae strains, from Prescott & Dunn medium added with sugarcane bagasse. A total of 107 conidia/mL of each A. welwitschiae UELAs 15.262 (wild type) and UELAs 15.262/35 (mutant) strains were grown in triplicate for 6 days at 37 °C in Prescott & Dunn medium added with sugarcane bagasse. Every 24 hours the crude extract of a triplicate of each strain of A. welwitschiae was collected for identification and quantification of CA by pyridine acetic anhydride. The crude extract was also used for determination of reducing sugars and cellulase activity. In the results obtained, gradual increase in CA production was observed until the fifth day of fermentation, with the highest CA production obtained on fifth day by both A. welwitschiae UELAs 15.262 (0.37 g/L) and A. welwitschiae UELAs 15.262/35 (0.47 g/L) strains, followed by decrease in CA production on the sixth day of fermentation. Under the same conditions, there was a gradual decrease in reducing sugars starting on the first day of fermentation for both strains (0.72 g/L 1st day to 0.37g/L – 6th day - average amount of reducing sugars between both A. welwitschiae strains). The cellulase activity during the fermentation process reached higher production on the sixth day for UELAs 15.262 strain (0.34 U/mL) and on the fifth day by the UELAs 15.262/35 strain (0.32 U/mL). The both A. welwitschiae strains showed potential for citric acid production from sugarcane residue, however A. welwitschiae UELAs 15.262/35 strain presents higher potential CA production from sugarcane residue.

Institutions
  • 1 Departamento de Bioquímica e Biotecnologia / Centro de Ciências Exatas / Universidade Estadual de Londrina
Track
  • Innovation and Biotechnology
Keywords
ASPERGILLUS WELWITSCHIAE
CITRIC ACID
Sugarcane residue