Aso Y, Nomura Y, Sano M, Sato R, Tanaka T, Ohara H, Matsumoto K, Wada K. Caprylic acid enhances hydroxyhexylitaconic acid production in Aspergillus niger S17-5.
J Appl Microbiol 2020;
130:1972-1980. [PMID:
33064909 DOI:
10.1111/jam.14900]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/19/2020] [Accepted: 10/12/2020] [Indexed: 11/30/2022]
Abstract
AIM
Aspergillus niger S17-5 produces two alkylitaconic acids, 9-hydroxyhexylitaconic acid (9-HHIA) and 10-hydroxyhexylitaconic acid (10-HHIA), which have cytotoxic and polymer building block properties. In this study, we characterized the production of 9-HHIA and 10-HHIA by addition of their expected precursor, caprylic acid, to a culture of A. niger S17-5, and demonstrated batch fermentation of 9-HHIA and 10-HHIA in a jar fermenter with DO-stat.
METHODS AND RESULTS
Production titres of 9-HHIA and 10-HHIA from 3% glucose in a flask after 25 days cultivation were 0·35 and 1·01 g l-1 respectively. Addition of 0·22 g l-1 of caprylic acid to a suspension of resting cells of A. niger S17-5 led to 32% enhancement of total 9-HHIA and 10-HHIA production compared to no addition. No enhancement of the production of 9-HHIA or 10-HHIA by the addition of oxaloacetic acid was observed. Addition of caprylic acid to the culture at mid-growth phase was more suitable for 9-HHIA and 10-HHIA production due to less cell growth inhibition by caprylic acid. DO-stat batch fermentation with 3% glucose and 14·4 g l-1 of caprylic acid in a 1·5 l jar fermenter resulted in the production titres of 9-HHIA and 10-HHIA being 0·48 and 1·54 g l-1 respectively after 10 days of cultivation.
CONCLUSIONS
Addition of caprylic acid to the culture of A. niger S17-5 enhances 9-HHIA and 10-HHIA production.
SIGNIFICANCE AND IMPACT OF THE STUDY
These results suggest that 9-HHIA and 10-HHIA are synthesized with octanoyl-CoA derived from caprylic acid, and that the supply of octanoyl-CoA is a rate-limiting step in 9-HHIA and 10-HHIA production. To the best of our knowledge, this is the first report regarding the fermentation of naturally occurring itaconic acid derivatives in a jar fermenter.
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