Dual Transcriptional Profile of <i>Aspergillus flavus</i> during Co-Culture with <i>Listeria monocytogenes</i> and Aflatoxin B1 Production: A Pathogen–Pathogen Interaction

• Main Authors: Iliada K. Lappa, Angeliki Maria Dionysopoulou, Spiros Paramithiotis, Maria Georgiadou, Eleftherios H. Drosinos
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Pathogens
• Subjects: <i>listeria monocytogenes</i>; <i>aspergillus flavus</i>; interaction; gene expression; aflatoxins
• Online Access: https://www.mdpi.com/2076-0817/8/4/198

The objective of this study was to investigate the effect of growth temperature and co-culture of <i>Aspergillus flavus</i> with <i>Listeria monocytogenes</i> on the production of Aflatoxin B1 (AFB1) and the transcriptional profile of associated regulatory and biosynthetic genes. The transcription of virulence- and homeostasis-associated genes of <i>L. monocytogenes</i> was also assessed. For this purpose, mono- and co-cultures of <i>L. monocytogenes</i> strain LQC 15257 and <i>A. flavus</i> strain 18.4 were inoculated into Malt Extract broth and allowed to grow for seven days at 25 &#176;C and 30 &#176;C. AFB1 quantification was performed by HPLC analysis and gene expression assessment by RT-qPCR. AFB1 production was lower at 30 &#176;C compared to 25 &#176;C during monoculture and also lower during co-cultures at both temperatures. This was accompanied by downregulation of <i>aflM</i>, <i>aflR</i>, <i>aflP</i>, and <i>aflS</i> during monoculture and <i>aflM</i> and <i>aflS</i> during co-culture at 30 &#176;C. On the other hand, transcription of <i>prfA, plcA</i>, <i>plcB</i>, <i>inlA</i>, <i>inlB</i>, <i>inlJ</i>, <i>murE</i>, <i>accA</i>, <i>acpP</i>, as well as <i>fapR</i>, was not affected. <i>sigB</i> gene was downregulated after co-culture with the fungus at 25 &#176;C and <i>hly</i> was downregulated after monoculture at 30 &#176;C compared to 25 &#176;C. In this work, the molecular interactions between <i>A. flavus</i> and <i>L. monocytogenes</i> were studied for the first time, offering a novel insight into their co-occurrence. Monitoring of their toxigenic and virulence potential at the molecular level revealed a complex dynamic in natural ecosystems.