Biodegradation of Ochratoxin A by Aspergillus tubingensis Isolated from Meju

Abstract

Ochratoxin A (OTA), a mycotoxin, contaminates agricultural products and poses a serious threat to public health worldwide. Microbiological methods are known to be a promising approach for OTA biodegradation because physical and chemical methods have practical limitations. In the present study, a total of 130 fungal isolates obtained from 65 traditional Korean meju (a fermented starter for fermentation of soybeans) samples were examined for OTA-biodegradation activity using thin-layer chromatography. Two fungal isolates were selected for OTA-biodegradation activity and were identified as M036 and M074 through sequence analysis of the beta-tubulin gene. After culturing both isolates in Soytone-Czapek medium containing OTA (40 ng/ml), OTA-biodegradation activity was analyzed using high-performance liquid chromatography (HPLC). Both strains degraded OTA by more than 95.0% after 14 days, and the HPLC analysis showed that the OTA biodegradation by the strains led to the production of ochratoxin α, which is much less toxic than OTA. Moreover, crude enzymes from the cultures of A. tubingensis M036 and M074 led to OTA biodegradation of 97.5% and 91.3% at pH 5, and 80.3% and 75.3% at pH 7, respectively, in a buffer solution containing OTA (40 ng/ml) after 24 h. In addition, the OTA-biodegrading fungi did not exhibit OTA production activity. Our data suggest that isolates and their enzymes have the potential for practical application to reduce levels of OTA in food and feed.

Detoxification of Mycotoxins through Biotransformation

“…(4R)-4-Hydroxyochratoxin A methyl ester (146) Hydroxylation and esterification Cell cultures of wheat and maize [31] (4S)-4-Hydroxyochratoxin A methyl ester (147) Hydroxylation and esterification Cell cultures of wheat and maize [31] (4R)-4-Hydroxyochratoxin A 4-O-β-D-glucoside (148) Hydroxylation and glycosylation Cell cultures of wheat and maize [31] (4S)-4-Hydroxyochratoxin A 4-O-β-D-glucoside (149) Hydroxylation and glycosylation…”

“…OTA (21) can be produced by various Aspergillus and Penicillium species. The most effective detoxification for OTA (21) was hydrolysis with transformed products as OTα (118) and phenylalanine (119) by several bacterial and fungal species ( Figure S57) [94][95][96][97][98][145][146][147]. The main transformation pathways of OTs are as follows [16].…”

“…OTA (21) could be hydrolyzed into OTα (118) and phenylalanine (Phe, 119) by bacteria such as Bacillus amyloliquefaciens [98], Alcaligenes faecalis [145] and Brevibacterium sp. [146], as well as fungi such as Aspergillus niger [97] and A. tubingensis [147]. OTA (21) was further hydrolyzed into OTα (118) by carboxypeptidase produced by bacteria and fungi [94].…”

Whole-genome sequencing of Aspergillus tubingensis G131 and overview of its secondary metabolism potential

“…Due to their versatile metabolism, those fungi are one of the most prolific sources of enzymes, organic acids and secondary metabolites (SM) with biomedical and biotechnological interests [1][2][3][4]. Already described as non-mycotoxins producer in comparison to A. niger [5][6][7][8][9], A. tubingensis, which is part of the A. niger clade of the black Aspergilli, represents a good alternative for metabolites production in industrial fermentation and is already used for some applications [10][11][12].…”

Natural occurrence of aflatoxins and ochratoxin A in meju and soybean paste produced in South Korea

“…Various microorganisms are known to inhibit mycotoxin production. Cho and co-workers reported the degradation of OTA using A. tubingensis isolated from meju [31]. In their study, OTA degradation was about 95% after 14 days.…”