• Home
  • Search Results
  • The influence of salt (NaCl) on ochratoxin A biosynthetic genes, growth and ochratoxin A production by three strains of Penicillium nordicum on a dry-cured ham-based medium.

The influence of salt (NaCl) on ochratoxin A biosynthetic genes, growth and ochratoxin A production by three strains of Penicillium nordicum on a dry-cured ham-based medium.

International journal of food microbiology (2014-04-02)
Alicia Rodríguez, Ángel Medina, Juan J Córdoba, Naresh Magan
ABSTRACT

Iberian dry-cured ham is colonised by moulds during the ripening process. The environmental conditions occurring during the process including the salt content predisposes the surface to colonisation by Penicillium species, including Penicillium nordicum which can contaminate the curing ham with ochratoxin A (OTA). The objective of this study was to examine the effect of NaCl (10% and 22%=0.94 and 0.87 water activity (aw)) on the activation of two genes involved in the biosynthetic pathway for OTA production, otapksPN and otanpsPN, relative growth and phenotypic OTA production by three strains of P. nordicum (CBS 110.769, FHSCC1 and FHSCC2) on a ham-based medium over a period of 12days at 25°C. Growth of the three strains was faster at 0.87 than 0.94 aw on the ham-based media. However, some intra- and inter-strain differences were observed. Of the three strains, only two (CBS 110.789; FHSCC2) were able to express the two genes involved in the biosynthesis of OTA in the two salt treatments. RT-qPCR showed that the temporal expression of the two genes (otapksPN and otanpsPN) was relatively similar for the wild type strain (FHSCC2) at both 0.94 and 0.87 aw over the 12day period. However, in the type strain (CBS 110.769) expression increased rapidly at 0.94 aw but was significantly lower at 0.87 aw. Expression of these two genes occurred after 3day incubation, while phenotypic OTA production was observed only after 6days in the two toxigenic strains. The other strain did not produce any OTA. The OTA concentrations confirmed the results observed with the molecular tools. This suggests that the RT-qPCR gene expression of these two genes may be a good early indicator of potential contamination of dry-cured ham with OTA during dry-cured ham ripening.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium chloride, BioXtra, ≥99.5% (AT)
Sigma-Aldrich
Sodium chloride, for molecular biology, DNase, RNase, and protease, none detected, ≥99% (titration)
Sigma-Aldrich
Sodium chloride solution, 0.9% in water, BioXtra, suitable for cell culture
Sigma-Aldrich
Sodium chloride, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99%
Sigma-Aldrich
Sodium chloride solution, 5 M in H2O, BioReagent, for molecular biology, suitable for cell culture
Sigma-Aldrich
Sodium chloride solution, 5 M
SAFC
Sodium chloride solution, 5 M
Sigma-Aldrich
Sodium chloride, meets analytical specification of Ph. Eur., BP, USP, 99.0-100.5%
Supelco
Ochratoxin A solution, 10 μg/mL in acetonitrile, analytical standard
Sigma-Aldrich
Sodium chloride, BioUltra, for molecular biology, ≥99.5% (AT)
Supelco
Sodium chloride, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Ochratoxin A, from Petromyces albertensis, ≥98% (HPLC)
Sigma-Aldrich
Sodium chloride solution, 0.85%
Sigma-Aldrich
Sodium chloride solution, BioUltra, for molecular biology, ~5 M in H2O
Sigma-Aldrich
Sodium chloride, 99.999% trace metals basis
Supelco
Sodium chloride, certified reference material for titrimetry, certified by BAM, ≥99.5%
Sigma-Aldrich
Sodium chloride, BioPerformance Certified, ≥99% (titration), suitable for insect cell culture, suitable for plant cell culture
Sigma-Aldrich
Sodium chloride, tested according to Ph. Eur.
Supelco
Ochratoxin A, from Aspergillus ochraceus, reference material
Sigma-Aldrich
Sodium chloride, tablet
Sigma-Aldrich
Sodium chloride, AnhydroBeads, −10 mesh, 99.999% trace metals basis
Sigma-Aldrich
Sodium chloride, random crystals, optical grade, 99.9% trace metals basis
Sigma-Aldrich
Sodium chloride, AnhydroBeads, −10 mesh, 99.99% trace metals basis