Antimicrobial activity of apitoxin from Apis mellifera in Salmonella enterica strains isolated from poultry and its effects on motility, biofilm formation and gene expression

Salmonella enterica is one of the most prevalent foodborne pathogens. The large quantity of serovar types results in the colonization of a large spectrum of hosts, with different environmental conditions and hazards. The aim of this study was to evaluate the differences in gene expression (bcsA and csgD) of Salmonella enterica serovars Heidelberg, Kentucky, and Enteritidis during biofilm formation using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Overall, there appeared to be differences in expression between the different serovars with high variation between strains. These data are important as they demonstrate considerable variability in gene expression between serovars and strains of poultry isolates of Salmonella enterica.

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Genetic Determinants of Salmonella Resistance to the Biofilm-Inhibitory Effects of a Synthetic 4-Oxazolidinone Analog

Applied and Environmental Microbiology ◽

10.1128/aem.01120-20 ◽

2020 ◽

Vol 86 (20) ◽

Cited By ~ 1

Author(s):

K. F. Griewisch ◽

J. G. Pierce ◽

J. R. Elfenbein

Keyword(s):

Gene Expression ◽

Natural Products ◽

Antimicrobial Resistance ◽

Salmonella Enterica ◽

Biofilm Formation ◽

Efflux Pump ◽

Single Gene ◽

Synthetic Analogs ◽

Content Type ◽

Matrix Gene

ABSTRACT Biofilms formed by Salmonella enterica are a frequent source of food supply contamination. Since biofilms are inherently resistant to disinfection, new agents capable of preventing biofilm formation are needed. Synthetic analogs of 4-oxazolidinone containing natural products have shown promise as antibiofilm compounds against Gram-positive bacteria. The purpose of our study was 2-fold: to establish the antibiofilm effects and mechanism of action of a synthetic 4-oxazolidinone analog (JJM-ox-3-70) and to establish mechanisms of resistance to this compound in Salmonella enterica serovar Typhimurium (S. Typhimurium). JJM-ox-3-70 inhibited biofilm formation but had no effect on cell growth. The antibiofilm effects were linked to disruption of curli fimbriae and flagellar gene expression and alteration in swimming motility, suggesting an effect on multiple cellular processes. Using a 2-step screening approach of defined multigene and single-gene deletion mutant libraries, we identified 3 mutants that produced less biofilm in the presence of JJM-ox-3-70 than the isogenic WT, with phenotypes reversed by complementation in trans. Genes responsible for S. Typhimurium resistance to the compound included acrB, a component of the major drug efflux pump AcrAB-TolC, and two genes of unknown function (STM0437 and STM1292). The results of this study suggest that JJM-ox-3-70 inhibits biofilm formation by indirect inhibition of extracellular matrix production that may be linked to disruption of flagellar motility. Further work is needed to establish the role of the newly characterized genes as potential mechanisms of biofilm intrinsic antimicrobial resistance. IMPORTANCE Biofilms are resistant to killing by disinfectants and antimicrobials. S. enterica biofilms facilitate long-term host colonization and persistence in food processing environments. Synthetic analogs of 4-oxazolidinone natural products show promise as antibiofilm agents. Here, we show that a synthetic 4-oxazolidinone analog inhibits Salmonella biofilm through effects on both motility and biofilm matrix gene expression. Furthermore, we identify three genes that promote Salmonella resistance to the antibiofilm effects of the compound. This work provides insight into the mechanism of antibiofilm effects of a synthetic 4-oxazolidinone analog in Gram-negative bacteria and demonstrates new mechanisms of intrinsic antimicrobial resistance in Salmonella biofilms.

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Effects of Environmental Conditions (temperature, pH, and glucose) on Biofilm Formation of Salmonella enterica serotype Kentucky and Virulence Gene Expression

Poultry Science ◽

10.1016/j.psj.2021.101209 ◽

2021 ◽

pp. 101209

Author(s):

Pantu Kumar Roy ◽

Angela Ji-Won Ha ◽

Md. Furkanur Rahaman Mizan ◽

Md. Iqbal Hossain ◽

Md. Ashrafudoulla ◽

...

Keyword(s):

Gene Expression ◽

Environmental Conditions ◽

Salmonella Enterica ◽

Biofilm Formation ◽

Virulence Gene ◽

Virulence Gene Expression

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

Antibiotics ◽

10.3390/antibiotics8040265 ◽

2019 ◽

Vol 8 (4) ◽

pp. 265 ◽

Cited By ~ 4

Author(s):

Alexandre Lamas ◽

Patricia Regal ◽

Beatriz Vázquez ◽

Alberto Cepeda ◽

Carlos Manuel Franco

Keyword(s):

Gene Expression ◽

Fatty Acids ◽

Antimicrobial Activity ◽

Acetic Acid ◽

Gut Microbiota ◽

Propionic Acid ◽

Butyric Acid ◽

Biofilm Formation ◽

Short Chain Fatty Acids ◽

Subinhibitory Concentrations

Short chain fatty acids (SCFAs) are commonly produced by healthy gut microbiota and they have a protective role against enteric pathogens. SCFAs also have direct antimicrobial activity against bacterial pathogens by diffusion across the bacterial membrane and reduction of intracellular pH. Due to this antimicrobial activity, SCFAs have promising applications in human health and food safety. In this study, the minimum inhibitory concentrations (MICs) of four SCFAs (acetic acid, butyric acid, propionic acid, and valeric acid) in Salmonella strains isolated from poultry were determined. The effect of subinhibitory concentrations of SCFAs in Salmonella biofilm formation, motility, and gene expression was also evaluated. Butyric acid, propionic acid, and valeric acid showed a MIC of 3750 µg/mL in all strains tested, while the MIC of acetic acid was between 1875 and 3750 µg/mL. Subinhibitory concentrations of SCFAs significantly (p < 0.05) reduced the motility of all Salmonella strains, especially in the presence of acetic acid. Biofilm formation was also significantly (p < 0.05) lower in the presence of SCFAs in some of the Salmonella strains. Salmonella strain. Salmonella Typhimurium T7 showed significant (p < 0.05) upregulation of important virulence genes, such as invA and hilA, especially in the presence of butyric acid. Therefore, SCFAs are promising substances for the inhibition of the growth of foodborne pathogens. However, it is important to avoid the use of subinhibitory concentrations that could increase the virulence of foodborne pathogen Salmonella.

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