Screening, Identification and Growth Characterization of Strains Inhibiting the Growth and Synthesis of Ochratoxin A by Aspergillus niger in Hams

Ochratoxin A (OTA) was a common mycotoxin in dry-cured hams, posing a significant threat to consumer health. Aspergillus niger A-8 serves as the primary OTA-producing fungus in ham in Panxian County, Guizhou Province. To identify strains capable of inhibiting OTA production by A. niger A-8, three strains (QF3, KF4, and RS18) were selected to assess their potential biocontrol ability, including antifungal activity, the impact of NaCl content on growth and antifungal activity, and their ability to inhibit OTA production in ham media. Simultaneously, the three strains underwent haemolytic, morphological and 16S rDNA identification, along with growth characterization. Results showed that all three strains exhibited robust antifungal activity against A. niger A-8. Although a high NaCl concentration (8%) hindered their growth, it did not compromise their antifungal efficacy. These strains effectively (P<0.05) suppressed the synthesis of OTA by A. niger A-8 in ham medium. Notably, only strain RS18 inhibited OTA production under simulated ham fermentation temperature conditions, and none exhibited hemolytic activity. Further analysis revealed that strain QF3 belonged to Weissella halotolerans, while strains KF4 and RS18 were identified as Lactiplantibacillus plantarum. All three strains displayed favorable growth characteristics within the temperature range of 17~42 ℃ and pH5~9. In conclusion, RS18 strong antifungal and OTA-producing inhibitory activities, showcasing its potential as a biocontrol bacterium capable of preventing and controlling OTA contamination in naturally fermented dry-cured hams. Additionally, this study reported the inhibitory effect of W. halotolerans on the growth and OTA synthesis of A. niger for the first time, that would provide the valuable insights for novel biocontrol management against OTA contamination during the natural fermentation of Chinese dry-cured hams.