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Microscopic and transcriptomic characterization of Listeria monocytogenes aggregation and biofilm formation on stainless steel surfaces in the presence of cantaloupe juice extract

ABSTRACT: Listeria monocytogenes (Lm) cells can attach to both cantaloupe surface and food contact surfaces and promote biofilm growth. This study was to understand the impact of cantaloupe juice on the physiology and transcriptome of Lm planktonic cells and biofilm cells grown on stainless steel coupons using confocal laser scanning microscopy (CLSM), Cryo-Scanning Electron Microscopy (Cryo-SEM) and RNA Seq technology. Lm showed a strong autoaggregation phenotype when grown in cantaloupe juice at room temperature. It is interesting to note that Lm formed significantly more biofilms on stainless steel (SS) coupons when grown in cantaloupe juice than in TSB. SEM images revealed a different attachment profile of Lm on SS coupons. In TSB, Lm cells were mainly found in scratches/groves of the metal surface, whereas, in cantaloupe juice they attached to the smooth surface as well. Interestingly, Lm planktonic and biofilm cells in cantaloupe juice showed an elongated cell shape which might be a stress-induced phenotype in cantaloupe juice. Cantaloupe juice induced a distinct transcriptional profile of biofilm and planktonic cells of Lm from TSB. Functional annotation indicated that the significantly differentially expressed genes (DEGs, Padj < 0.05, log2foldchange ≥ 1) from the comparison mainly participated in metabolism, signaling and stress response. Notably, certain pathways downregulated for planktonic cells were significantly upregulated for biofilm cells in cantaloupe juice compared to TSB, including ABC transporters, two-component system, quorum sensing, chemotaxis, and flagellar assembly. These data highlighted the interaction of Lm with food matrix (i.e., cantaloupe) and the role of food matrix on Lm survival and adaptation. These results provided the basis for future functional characterization of genes with potential roles in biofilm formation and persistence of Lm in cantaloupe juice, as well as for development of mitigation practices for Lm biofilms on produce and food contact surfaces.

ORGANISM(S): Listeria monocytogenes

PROVIDER: GSE243459 | GEO | 2023/09/18

REPOSITORIES: GEO

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Project description:Otitis media, pneumonia, sinusitis and as well as severe diseases such as meningitis and bacteraemia are related to biofilm-like diseases, in which Streptococcus pneumoniae demonstrated differential and tissue specific gene expressions. In this study, we reported the differential gene expression profile of early in vitro biofilm and planktonic cell in c-DNA microarray analysis. The microarray analysis was performed on total RNA extracted from biofilms grown in 24-well microtiter plate and mid-log grown planktonic cells. To validate the results of microarray, real-time RT-PCR was performed on 13 differentially expressed genes and one constitutively expressed gene from six different functional groups. cDNA-microarray analyses indicated 89 genes that were significantly differentially expressed in biofilm and planktonic cells. Among total differentially expressed gene, almost 50% were hypothetical genes. Of the 46 protein coding genes, 34 showed up-regulation and 16 showed down-regulation in biofilm. The functional annotation showed that many functional categories were differentially regulated in biofilm and planktonic cells, such as genes involve in purine, pyrimidine nucleotide metabolism, RNA/DNA metabolism, amino acid transport and metabolism, translation, transporter protein, carbohydrate transport and metabolism, cell wall biosynthesis, isoprenoid biosynthesis, transcription regulator and cellular process. Streptococcus pneumoniae R6 strain used in this is an unencapsulated and avirulent strain derived from encapsulated serotype 2 pathogenic strain D39. In vitro biofilm formation was carried out in 24-well, flat-bottom, polystyrene microtiter plate (BD falcon, MD, USA) in static model. S. pneumoniae grown up to mid-logarithmic phase in TSB medium was diluted 1:100 with fresh sterile TSB medium supplied with 1% glucose, inoculated 1.5 mL in 24-well microtiter plate and, incubated for 15 hours at 37M-BM-0C in 5% CO2. After incubation medium was discarded, and the plates were gently washed three times with 1.5 mL sterile, cold phosphate buffer saline (PBS). Adherent cell were scraped and immediately processed for RNA extraction. For planktonic cells RNA extraction, five ml of mid-logarithmic phase cell suspension was pelleted by centrifugation and wash three times with sterile PBS and immediately processed for RNA extraction. All experiments were performed in triplicate (3 independent biological replicates)

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Microscopic and transcriptomic characterization of Listeria monocytogenes aggregation and biofilm formation on stainless steel surfaces in the presence of cantaloupe juice extract

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