Background: Agro-industrial residues consist of various wastes from the agriculture and the food industry, which account for several thousand tonnes of waste per year. These wastes pollute the environment and represent a loss of biomass which can otherwise be processed to other value-added products through the activities of microorganisms. This study aims to ferment the seed cake of Jatropha curcas an agro-based waste, for the production of gibbererllic acid using Aspergillus niger (ATCC 16404) and Aspergillus terreus (ATCC 20542) in submerged fermentation. Methods: The seeds of Jatropha were cracked, ground and defatted. The ground seeds were pretreated with 0.5% tetraoxosulphate VI acid (w/v), then fermented separately in a modified Czapek Dox broth using the test organisms. Carboxylmethylcellulose (CMC) used as control.The fermentation conditions were: pH 5.3; substrate concentration 1.5g; inocula size 2 mL; (1.2 x 107 spores/mL A. niger) (5.83 x 106 spores/mL A. terreus); temperature 250C; fermentation period of 7 days. Results: Gibberellic acid yield of 13.8±0.97 g/L and 12.2±0.97 g/L was produced by A. niger and A. terreus respectively. The yield from the CMC substrate was 5.60±0.49 and 2.0±0.32 g/L from A. niger and A. terreus respectively. The fermentation parameters were then varied in order to optimize the yield of the acid. The highest yield of gibberellic acid was 31.0±0.23 g/L and 32.8±0.25 g/L at pH 5, substrate concentration 1.5g, inocula size 2 mL for 8 days; and pH 7, substrate concentration 3.5g and inocula size 2ml for 8 days with A. niger and A. terreus respectively, representing a 55% and 63% yield increase by A. niger and A. terreus respectively. Conclusion: These results support the potential use of Jatropha seed cake for gibberellic acid production.
Full conference title:
- ASM 115th (2015)