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Guided Protocol for Fecal Microbial Characterization by 16S rRNA-Amplicon Sequencing
Published on: March 19, 2018
Polyphasic characterization of bacterial community in fresh cut salads
Cinzia Lucia Randazzo1, Giovanna Ombretta Scifò, Filippo Tomaselli
1DOFATA, Laboratory of Microbiology, University of Catania, Via Santa Sofia, 98, 95123 Catania, Italy. cinzialuci@tiscali.it
Abstract:
In the present work we describe a polyphasic study of bacterial community in fresh cut salads packaged under ordinary and modified atmospheres. Samples of fresh cut salads were aseptically collected at 0, 3, and 6 days of storage and analysed both by culture-dependent and -independent methods. DNA extracted from fresh cut salad samples was used as a template for PCR amplification of 16 S rRNA gene; the PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE); finally, clone libraries of 16 S rRNA gene from the fresh cut salad was constructed. Results of plating count revealed a significant increase of all microbial loads in fresh-cut salad samples packaged in OA and that the microbial growth of the different groups was significantly affected by the conditions applied for MA packaging. A constant presence, throughout storage, of the pathogenic bacteria in all the fresh-cut salads samples was highlighted by PCR-DGGE analysis. Therefore, the polyphasic approach used in the present study allowed us to characterize the main species involved in the fresh cut salad products and to better understand their dynamics throughout storage.
Insights
This study analyzed bacterial communities in fresh-cut salads using culture-dependent and -independent methods. Pathogenic bacteria were consistently present, highlighting the need for careful packaging and handling of fresh-cut salads.
Area of Science:
- Microbiology
- Food Science
- Molecular Biology
Background:
- Fresh-cut salads are susceptible to microbial contamination.
- Packaging atmosphere significantly impacts microbial growth in fresh-cut produce.
- Understanding bacterial dynamics is crucial for food safety.
Purpose of the Study:
- To characterize the bacterial community in fresh-cut salads under different packaging conditions.
- To assess the impact of ordinary (OA) and modified atmospheres (MA) on microbial growth.
- To identify the presence of pathogenic bacteria during storage.
Main Methods:
- Polyphasic approach combining culture-dependent and -independent methods.
- Aseptic collection of salad samples at 0, 3, and 6 days of storage.
- DNA extraction, PCR amplification of 16S rRNA gene, DGGE analysis, and clone library construction.
Main Results:
- Significant increase in microbial loads in salads packaged under OA.
- MA packaging conditions significantly affected microbial growth.
- Pathogenic bacteria were consistently detected throughout storage in all samples.
Conclusions:
- The polyphasic approach effectively characterized bacterial communities in fresh-cut salads.
- Packaging atmosphere plays a critical role in controlling microbial proliferation.
- Continuous presence of pathogens underscores food safety concerns.
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