Thermal Resistance and Gene Expression of both Desiccation-Adapted and Rehydrated Salmonella enterica Serovar Typhimurium Cells in Aged Broiler Litter

Abstract

The objective of this study was to investigate the thermal resistance and gene expression of both desiccation-adapted and rehydrated Salmonella enterica serovar Typhimurium cells in aged broiler litter. S. Typhimurium was desiccation adapted in aged broiler litter with a 20% moisture content (water activity [a w ], 0.81) for 1, 2, 3, 12, or 24 h at room temperature and then rehydrated for 3 h. As analyzed by quantitative real-time reverse transcriptase PCR (qRT-PCR), the rpoS, proV, dnaK, and grpE genes were upregulated (P Ͻ 0.05) under desiccation stress and could be induced after 1 h but in less than 2 h. Following rehydration, fold changes in the levels of these four genes became significantly lower (P Ͻ 0.05). The desiccation-adapted ΔrpoS mutant was less heat resistant at 75°C than was the desiccation-adapted wild type (P Ͻ 0.05), whereas there were no differences in heat resistance between desiccation-adapted mutants in two nonregulated genes (otsA and PagfD) and the desiccation-adapted wild type (P Ͼ 0.05). Survival characteristics of the desiccation-adapted ΔPagfD (rdar [red, dry, and rough] morphotype) and ΔagfD (saw [smooth and white] morphotype) mutants were similar (P Ͼ 0.05). Trehalose synthesis in the desiccation-adapted wild type was not induced compared to a nonadapted control (P Ͼ 0.05). Our results demonstrated the importance of the rpoS, proV, dnaK, and grpE genes in the desiccation survival of S. Typhimurium. By using an ΔrpoS mutant, we found that the rpoS gene was involved in the crossprotection of desiccation-adapted S. Typhimurium against high temperatures, while trehalose synthesis or rdar morphology did not play a significant role in this phenomenon. In summary, S. Typhimurium could respond rapidly to low-a w conditions in aged broiler litter while developing cross-protection against high temperatures, but this process could be reversed upon rehydration.IMPORTANCE Physical heat treatment is effective in eliminating human pathogens from poultry litter used as biological soil amendments. However, prior to physical heat treatment, some populations of microorganisms may be adapted to the stressful conditions in poultry litter during composting or stockpiling, which may cross-protect them against subsequent high temperatures. Our previous study demonstrated that desiccation-adapted S. enterica cells in aged broiler litter exhibited enhanced thermal resistance. However, there is limited research on the underlying mechanisms of the extended survival of pathogens under desiccation conditions in animal wastes and cross-tolerance to subsequent heat treatment. Moreover, no information is available about the thermal resistance of desiccationadapted microorganisms in response to rehydration. Therefore, in the present study, we investigated the gene expression and thermal resistance of both desiccationadapted and rehydrated S. Typhimurium in aged broiler litter. This work will guide future research efforts to control human pathogens in animal wastes used as biological soil amendments.

The Microbial Lipopeptide Paenibacterin Disrupts Desiccation Resistance in Salmonella enterica Serovars Tennessee and Eimsbuettel

“…Paenibacterin's ability to interfere with cytoplasmic membrane functions could compromise desiccation resistance because these membranes are the sites where diffusion or uptake of osmoprotectant solutes and ions takes place. In addition, the cytoplasmic membrane is the site of fatty acid catabolism; this is needed to derive the energy required for S. enterica to survive desiccation stress (3,24,25). Transcription of four genes, namely, proV, kdpA, otsB, and STM1494, involved in proline accumulation, potassium ion transport, trehalose synthesis, and the osmoprotectant transport system, respectively (11,12), was analyzed in this study.…”

Cross Talk between Nitric Oxide and Calcium-Calmodulin Regulates Ganoderic Acid Biosynthesis in Ganoderma lucidum under Heat Stress

“…Quantitative real-time reverse transcriptase PCR (qRT-PCR) calculations analyzing the relative gene expression levels were performed according to the 2 ϪΔΔCT method described by Livak and Schmittgen (35). We considered a gene fold change of Ͼ2 and P value of Ͻ0.01 as reflecting a significant difference in expression (36). The gene fragments were amplified by real-time PCR using the primers shown in Table S1.…”

Short Chain Fatty Acids Commonly Produced by Gut Microbiota Influence Salmonella enterica Motility, Biofilm Formation, and Gene Expression

“…16s rRNA F: AGGCCTTCGGGTTGTAAAGT R: GTTAGCCGGTGCTTCTTCTG [39] luxS F: ATGCCATTATTAGATAGCTT R: GAGATGGTCGCGCATAAAGCCAGC [40] hilA F: AATGGTCACAGGCTGAGGTG R: ACATCGTCGCGACTTGTGAA [41] invA F: CGCGCTTGATGAGCTTTACC R: CTCGTAATTCGCCGCCATTG [41] rpoS F: CAAGGGGAAATCCGTAAACCC R: GCCAATGGTGCCGAGTATC [42] csrA F: CTGGACTGCTGGGATTTTTC R: CATGATTGGCGATGAGGTC [43] fliC F: CTCGGCTACTGGTCTTGGTG R: CCGTAACGGTAACTTTGGCG [44] ssrA F: CGGCTGGTATTCTTGTAAGGGT R: AAGCAGACACAAATTCGCAAG [45] stn F: CAACCAGATAGTAAAGACCG R: ATTAGCGTAGAGGCAAAAGA [46] fadA F: ATCTCTCCGCCCACTTAATGCGTA R: AGCCTTGCTCCAGCGTTTGTTGTA [42] sirA F: CCAGCTACTTTCGCAGCAA R: AACACGTTGTAACGCGGTTG [41] spiA F: AGGCGCTTGATATGTGC R: GCAGGCTCCGGAATTTTAGG [46] cpx F: CATTTAACGACCGCGAGCTG R: ACCCGGATTAAGGCTTAGCG [44] rpoE F: CACCTTACGGGAGCTGGATG R: GAAGATACGTGAACGCACCG [44] flijB F: ATGGTACTACACTGGATGTATCG R: GTAAAGCCACCAATAGTAAC [44] 3.6. Statistical Analysis GraphPad Prism 8 (GraphPad, CA, USA) was used for the statistical analyses.…”