Project description:Antimicrobial chemicals are widely applied to clean and disinfect food-contacting surfaces. However, the cellular response of bacteria, such as Bacillus cereus, to various disinfectants is unclear. In this study, the physiological and genome-wide transcriptional responses of B. cereus ATCC 14579 exposed to four different disinfectants (i.e., benzalkonium chloride, sodium hypochlorite, hydrogen peroxide, and peracetic acid) were analyzed. The physiological response of B. cereus to different concentrations of the disinfectants used was investigated. For each disinfectant, concentrations leading to the attenuation of growth, growth arrest, and cell death were studied in more detail. The simultaneous analysis of the transcriptional responses of B. cereus upon exposure to the different concentrations of disinfectants revealed common responses induced by the four disinfectants. Notably, genes involved in the general and oxidative stress responses were commonly up-regulated. Furthermore, the obtained results indicate that all the disinfectants also induce specific responses. Exposure to benzalkonium chloride, a disinfectant known to induce membrane damage, specifically induced genes involved in the fatty acid metabolism. Benzalkonium chloride induced-membrane damage was confirmed by fluorescence microscopy and fatty acid analysis confirmed that fatty acid composition of cell membrane was affected upon exposure to benzalkonium chloride. Sodium hypochlorite induced genes involved in sulfur and sulfur-containing amino acids metabolism, which correlated with the observed sodium hypochlorite-specific induction of oxidation of sulphydryl groups. Hydrogen peroxide and peracetic acid exposures induced genes involved in DNA damage and the SOS response. Notably, hydrogen peroxide and peracetic acid-treated cells exhibited higher mutation rates corroborating with the induced SOS response. Understanding the mechanisms displayed by microorganisms coping with disinfectants-induced stress may allow for design of more efficient sequential and/or disinfectant combination treatments in food processing environments.
Project description:The goals of this study are to use SWATH-MS to detect bacterial proteomic profiles of wild-type Acinetobacter baylyi ADP1, and its protein response under the exposure of disinfectants, including chloramine and free chlorine. The concentrations of disinfectants were 10 mg/L. The group without dosing disinfectant was the control group. Each concentration was conducted in triplicate. By comparing the proteomic profiles of experimental groups and control group, the effects of disinfectants on translational levels can be revealed.
Project description:Comparison of hexachlorocyclohexane (HCH) contaminated soils from Spain with a community-specific microarray. These results are being submitted for publication and represent the first use of microarrays for analysis of soil DNA and the first community-specific microarray design. Keywords: other
Project description:Disinfection is very critical for the removal of pathogens that constitute public health concerns. However, a rounded understanding of the antimicrobial action of different classes of disinfectants is still lacking. In this work, the physiological and transcriptomic responses of Escherichia coli to two different disinfectants namely: potassium ferrate (K2FeO4) and more conventional disinfectant, sodium hypochlorite (NaOCl), were examined. The study aimed to examine E. coli genetic response to ferrate and compare and contrast it to the genetic response of E. coli to hypochlorite.
Project description:Slaughterhouse environments are prone to microbial contamination, influenced by factors like set-up, size and area as well as disinfection practices. Thus, effective control measures are crucial to prevent the spread of pathogens and their contaminant genes (antimicrobial resistance genes and virulence factors) throughout the food chain. In the present study, we assessed the microbial contamination in environmental surfaces of three slaughterhouses located in the Jaén province (Spain). We also evaluated the impact of different disinfection strategies on microbial loads and diversity by means of culture dependent and independent methods. The results revealed a statistically significant inter- and intra-specific differences in microbial loads including the most important pathogens such as pseudomonads, staphylococci, Escherichia coli, Salmonella sp. and Campylobacter jejuni. Disinfection strategies using routine disinfectant (used by the slaughterhouse), HLE disinfectant, UV, or combinations thereof showed varying effectiveness. The newly developed sustainable HLE disinfectant was most effective, while UV had the lowest disinfection strength, and routine disinfectants failed to eradicate all pathogens. Metagenomic analysis identified Pseudomonadota as the dominant phylum, followed by Actinomycetota and Bacteroidota. Results furthermore indicated shifts from sacrifice to cold rooms, with an increase in Gammaproteobacteria, particularly Moraxellaceae (represented by Psychrobacter cryohalolentis) over Acinetobacter sp. In conclusion, this study highlights the potential of HLE disinfectant (alone or in combination with the routine disinfectant) as a more effective disinfection measure on environmental surfaces, particularly for combating multi-drug resistant pathogens compared to other disinfection methods currently used.
Project description:The goals of this study are to use Next-generation sequencing (NGS) to detect bacterial mRNA profiles of wild-type A.baylyi ADP1, and its mRNA response under the exposure of two disinfectants, chloramine and free chlorine. The concentrations 10 mg/L. The group without dosing disinfectants was the control group. Each concentration was conducted in triplicate. By comparing the mRNA profiles of experimental groups and control group, the effects of these two disinfectants on transcriptional levels can be revealed. Illumina HiSeq 2500 was applied. The NGS QC toolkit (version 2.3.3) was used to treat the raw sequence reads to trim the 3’-end residual adaptors and primers, and the ambiguous characters in the reads were removed. Then, the sequence reads consisting of at least 85% bases were progressively trimmed at the 3’-ends until a quality value ≥ 20 were kept. Downstream analyses were performed using the generated clean reads of no shorter than 75 bp. The clean reads of each sample were aligned to the A.baylyi ADP1 reference genome (NC_005966.1), using SeqAlto (version 0.5). Cufflinks (version 2.2.1) to calculate the strand-specific coverage for each gene, and to analyze the differential expression in triplicate bacterial cell cultures. The statistical analyses and visualization were conducted using CummeRbund package in R. (http://compbio.mit.edu/cummeRbund/). Gene expression was calculated as fragments per kilobase of a gene per million mapped reads (FPKM, a normalized value generated from the frequency of detection and the length of a given gene.