Detection and discrimination between ochratoxin producer and non-producer strains of Penicillium nordicum on a ham-based medium using an electronic nose

The aim of this work was to evaluate the potential use of qualitative volatile patterns produced by Penicillium nordicum to discriminate between ochratoxin A (OTA) producers and non-producer strains on a ham-based medium. Experiments were carried out on a 3% ham medium at two water activities (aw ; 0.995, 0.95) inoculated with P. nordicum spores and incubated at 25°C for up to 14days. Growing colonies were sampled after 1, 2, 3, 7 and 14days, placed in 30-ml vials, sealed and the head space analysed using a hybrid sensor electronic nose device. The effect of environmental conditions on growth and OTA production was evaluated based on the qualitative response. However, after 7days, it was possible to discriminate between strains grown at 0.995 aw, and after 14days, the OTA producer and non-producer strain and the controls could be discriminated at both aw levels. This study suggests that volatile patterns produced by P. nordicum strains may differ and be used to predict the presence of toxigenic contaminants in ham. This approach could be utilised in ham production as part of a quality assurance system for preventing OTA contaminatio

Ventilator associated pneumonia : analyses of volatile fingerprints for identification of causative microorganisms, assessment of anti-fungals and use of in vitro models for early clinical sample prediction

This study has involved the analysis of volatile fingerprints using a hybrid electronic nose (e-nose) to discriminate between and diagnose the microorganisms which cause ventilator–associated pneumonia (VAP), one of the most important infections in the hospital environment. This infection occurs in hospitalised patients with 48-72 hrs of mechanical ventilation. VAP diagnostics still remains a problem due to the lack of a precise diagnostic tool. The current tests are mostly based on quantitative cultures of samples from the lower lung airways with clinical findings, which do not often result in accurate diagnoses of the disease. Cont/d.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Ventilator associated pneumonia: analyses of volatile fingerprints for identification of causative microorganisms, assessment of anti-fungals and use of in vitro models for early clinical sample prediction

This study has involved the analysis of volatile fingerprints using a hybrid electronic nose (e-nose) to discriminate between and diagnose the microorganisms which cause ventilator–associated pneumonia (VAP), one of the most important infections in the hospital environment. This infection occurs in hospitalised patients with 48-72 hrs of mechanical ventilation. VAP diagnostics still remains a problem due to the lack of a precise diagnostic tool. The current tests are mostly based on quantitative cultures of samples from the lower lung airways with clinical findings, which do not often result in accurate diagnoses of the disease. Cont/d

Detection and discrimination between ochratoxin producer and non-producer strains of Penicillium nordicum on a ham-based medium using an electronic nose

Aims: To evaluate the potential use of volatile fingerprints produced by Penicillium nordicum to discriminate ochratoxin A (OTA) producers or non-producers strains on a ham-based medium. Methods and Results: Experiments were carried out on a 3% ham medium at two water activities (0.995, 0.95 aw) inoculated with P. nordicum spores and incubated at 25°C for up to 14 days. Agar discs were sampled after 1, 2, 3, 7 and 14 days, placed in 30 ml vials, sealed and the head space analysed using e-nose. The effect of environmental conditions on growth and OTA production was evaluated based on the qualitative response. PCA showed that after 72 hrs volatile fingerprints did not help discriminate between treatments, after 7 days, they were able to discriminate between strains grown at 0.995 aw and after 14 days the OTA producer and non-producer strain and the control could be discriminated at both aw. Conclusions: This study suggests that volatile fingerprints produced by P. nordicum strains may differ and be used to predict the presence of toxigenic contaminants in ham. Significance and impact of the study: This approach could be utilised in ham production as part of a quality assurance system for preventing OTA contamination

Use of volatile fingerprints to detect Penicillium nordicum strains producing ochratoxin A in ham.

The objective of this study was to evaluate (a) the effect of water availability on growth and ochratoxin A (OTA) production by Penicillium nordicum in a ham-based medium and (b) the potential for discriminating between producing (MPVP 1669) and non-producing strains (MPVP 1446) of P.nordicum using volatile production patterns with a hybrid sensor array system ((NST 3220 Lab Emission Analyser, Applied Sensors, Linköping, Sweden). Initial studies using a 3% ham-based medium were used to identify the water activity (aw) range for growth and OTA production at 25°C. This showed that growth occurred over the range 0.99 to 0.90 aw and was able to produce OTA after 7 and 14 days. Subsequent studies were carried out with both the producing and non-producing strains of P.nordicum to examine the potential for differentiation based on qualitative volatile production patterns. Thus the 3% ham media were inoculated with spores by spread plating onto the surface of 5 replicate treatment at 0.995 and 0.95 aw at 25°C for up to 14 days. Plates were destructively sampled after 1, 2, 3, 7 and 14 days. Agar discs (3 x 2 cm) were placed in vials and sealed, placed in the autosampler of the sensor array unit and the head space analysed after 1 hrs incubation. The maximum response of the sensor array (metal ion and metal oxide arrays) were used in the PCA statistical analyses of the data sets. Up to 72 hrs high associations were observed based on aw more than the capacity for the strains to produce OTA. In fact, the strain were grouped at aw 0.95 and 0.995. However, after 7 days incubation the e-nose was able to discriminate the two strains of P. nordicum grown at aw of 0.995, while strains at aw of 0.95 were associated. The most interesting results were obtained after 14 days incubation. The e-nose was able to discriminate between the producer and non-producer strains at both aw levels. This suggests that qualitative volatile production patterns may differ between these two strains because of the biosynthetic pathways involved. This supports previous work with Fusarium verticilioides where similar discrimination was obtained between fumonisin and non-fumonsin strains. The key volatile biomarkers now need to be identified and these may have potential for use as an early indicator of contamination of such food products by mycotoxigenic strains