scholarly journals Induction of a Viable but Nonculturable State, Thermal and Sanitizer Tolerance, and Gene Expression Correlation with the Desiccation Adapted Biofilm and Planktonic Salmonella in Powdered Infant Formula

2021 ◽  
Author(s):  
Guiliu Chen ◽  
Mengzhe Lin ◽  
Yingqi Chen ◽  
Weiying Xu ◽  
Hongmei Zhang
Keyword(s):  
Gene Expression ◽  
Infant Formula ◽  
Physiological State ◽  
Cross Protection ◽  
Plate Count ◽  
Powdered Infant Formula ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
And Storage ◽  
Planktonic State

This study investigated the effects of the physiological state, desiccation-adaptation, and storage of powdered infant formula (PIF) on Salmonella survival and their desiccation stress-related gene expression. PIF was inoculated with S . Typhimurium in the biofilm state on beads and in the planktonic state on nitrocellulose filters and stored at 25°C for up to 270 days. 5-cyano-2,3-ditoyl tetrazolium chloride flow cytometry (CTC-FCM) and Xylose Lysine Deoxycholate (XLD) plate count experiments demonstrated that biofilm-forming Salmonella tends to enter the Viable but Nonculturable (VBNC) state (p< 0.05). The population reduction of all desiccation-adapted S. Typhimurium decreased significantly in both physiological states after exposure to mild heat (60℃) compared with non-adapted control cells (p< 0.05). Salmonella showed heat cross-protection in both physiological states, but only the planktonic state Salmonella induced cross-protection against hydrogen peroxide. As indicated by quantitative reverse transcription polymerase chain reaction (RT-qPCR), rpoS of biofilm Salmonella for all days desiccation adatption examined and plantonic Salmonella on the 7th day of dry storage were significantly upregulated (p< 0.05).The rpoE , grpE , and invA genes in S almonella of both physiological states were significantly downregulated (p< 0.05). Physiological state and storage time might affect expression levels of these genes. In conclusion, prior exposure to these conditions, including low a w , and the physiological state posed an impact on Salmonella in the VBNC state and their gene expression.

scholarly journals Induction of Escherichia coli and Salmonella typhimurium into the viable but nonculturable state following chlorination of wastewater

2005 ◽  
Vol 3 (3) ◽  
pp. 249-257 ◽  
Author(s):  
James D. Oliver ◽  
Maya Dagher ◽  
Karl Linden
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Stationary Phases ◽  
Health Hazard ◽  
Physiological State ◽  
Treated Wastewater ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Nonculturable Cells ◽  
Nonculturable State

We examined the effects of chlorine disinfection on Escherichia coli and Salmonella typhimurium in secondary-treated wastewater to determine whether such treatment might induce these bacteria into the viable but nonculturable (VBNC) state. In this state, cells lose culturability but retain viability and the potential to revert to the metabolically active and infectious state. To examine the effects of chlorination on cells in different physiological states, cells from the logarithmic and stationary phases, or nutrient starved, or grown in natural wastewater, were studied. Isogenic cells with and without plasmids were also examined. Whereas a mixture of free and combined chlorine, as occurs under typical wastewater disinfection, was found to be rapidly lethal to most cells, regardless of their physiological state or plasmid content, c. 104 of the original 106 cells ml−1 did survive in the VBNC state. While we were not successful in resuscitating these cells to the culturable state, the presence of such nonculturable cells in treated wastewater offers a potential public health hazard.

scholarly journals Cell Wall Chemical Composition ofEnterococcus faecalis in the Viable but Nonculturable State

2000 ◽  
Vol 66 (5) ◽  
pp. 1953-1959 ◽  
Author(s):  
Caterina Signoretto ◽  
Maria del Mar Lleò ◽  
Maria Carla Tafi ◽  
Pietro Canepari
Keyword(s):  
Cell Wall ◽  
Chemical Composition ◽  
Physiological State ◽  
Teichoic Acid ◽  
Normal Growth ◽  
Lipoteichoic Acid ◽  
Growth Conditions ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Dividing Cells

ABSTRACT The viable but nonculturable (VBNC) state is a survival mechanism adopted by many bacteria (including those of medical interest) when exposed to adverse environmental conditions. In this state bacteria lose the ability to grow in bacteriological media but maintain viability and pathogenicity and sometimes are able to revert to regular division upon restoration of normal growth conditions. The aim of this work was to analyze the biochemical composition of the cell wall ofEnterococcus faecalis in the VBNC state in comparison with exponentially growing and stationary cells. VBNC enterococcal cells appeared as slightly elongated and were endowed with a wall more resistant to mechanical disruption than dividing cells. Analysis of the peptidoglycan chemical composition showed an increase in total cross-linking, which rose from 39% in growing cells to 48% in VBNC cells. This increase was detected in oligomers of a higher order than dimers, such as trimers (24% increase), tetramers (37% increase), pentamers (65% increase), and higher oligomers (95% increase). Changes were also observed in penicillin binding proteins (PBPs), the enzymes involved in the terminal stages of peptidoglycan assembly, with PBPs 5 and 1 being prevalent, and in autolytic enzymes, with a threefold increase in the activity of latent muramidase-1 in E. faecalis in the VBNC state. Accessory wall polymers such as teichoic acid and lipoteichoic acid proved unchanged and doubled in quantity, respectively, in VBNC cells in comparison to dividing cells. It is suggested that all these changes in the cell wall of VBNC enterococci are specific to this particular physiological state. This may provide indirect confirmation of the viability of these cells.

scholarly journals In Situ and In Vitro Gene Expression by Vibrio vulnificus during Entry into, Persistence within, and Resuscitation from the Viable but Nonculturable State

2006 ◽  
Vol 72 (2) ◽  
pp. 1445-1451 ◽  
Author(s):  
Ben Smith ◽  
James D. Oliver
Keyword(s):  
Gene Expression ◽  
Vibrio Vulnificus ◽  
De Novo ◽  
In Vitro Studies ◽  
Direct Result ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Cold Shock Response

ABSTRACT Isolation of Vibrio vulnificus during winter months is difficult due to the entrance of these cells into the viable but nonculturable (VBNC) state. While several studies have investigated in vitro gene expression upon entrance into and persistence within the VBNC state, to our knowledge, no in situ studies have been reported. We incubated clinical and environmental isolates of V. vulnificus in estuarine waters during winter months to monitor the expression of several genes during the VBNC state and compared these to results from in vitro studies. katG (periplasmic catalase) was down-regulated during the VBNC state in vitro and in situ compared to the constitutively expressed gene tufA. Our results indicate that the loss of catalase activity we previously reported is a direct result of katG repression, which likely accounts for the VBNC response of this pathogen. While expression of vvhA (hemolysin) was detectable in environmental strains during in situ incubation, it ceased in all cases by ca. 1 h. These results suggest that the natural role of hemolysin in V. vulnificus may be in osmoprotection and/or the cold shock response. Differences in expression of the capsular genes wza and wzb were observed in the two recently reported genotypes of this species. Expression of rpoS, encoding the stress sigma factor RpoS, was continuous upon entry into the VBNC state during both in situ and in vitro studies. We found the half-life of mRNA to be less than 60 minutes, confirming that mRNA detection in these VBNC cells is a result of de novo RNA synthesis.

Investigation of microbial contamination of Powdered Infant Formula during different storage periods after opening

2019 ◽  
Vol 10 (03) ◽  
Author(s):  
Mohammed Khalid Al-atrash
Keyword(s):  
Infant Formula ◽  
Environmental Protection Agency ◽  
Microbial Contamination ◽  
Total Coliform ◽  
Viable Count ◽  
Risk Level ◽  
Powdered Infant Formula ◽  
Total Viable Count ◽  
Coliform Count ◽  
Significant Difference

The present study was carried out to knowing effect different storage periods of the microbial quality for the Powdered Infant Formula (PIF) after opening the tin, and ensuring from the safety note (after opening, use within 3 weeks). Thirty (30) samples of (PIF) from category (1 – 6 months) in five different types are collected from pharmacies and local markets in Baquba city / Iraq, which are used as substitutes for breast milk during the first day of opening the tin powders such as Total viable count, Total coliform count, Salmonella count and Yeast and Molds count. These experiments repeated at each week of same samples within (5) weeks. Results were obtained at opening the tin, Total viable count (less than 0.05 1.0 x 103 ±1.5x10 CFU/g) were significantly higher than Total Coliform count (less than 0.05 ± 0.3 x 10 CFU/g) and Total Salmonella count (less than 0.05 0 x 10 CFU/g) and Yeasts and Molds (less than 0.05 ± 0.3 x 10 CFU/g). while results obtained at fifth week were (less than 0.05 8.8 x 103 ±5.5x102 CFU/g), (less than 0.05 0.9 x 102 ± 0.4x101 CFU/g), (less than 0.05 0 x 10 CFU/g), (less than 0.05 9.5 x 10 ± 1.2x101 CFU /g) respectively. All samples of (PIF) having non-significant difference. These results compared to Iraqi Quality Standards (IQS), all the results from the opening samples to fifth week were within the range of IQS and USA Environmental Protection Agency (USEPA) and as indicates the hygienic condition of (PIF) without risk level for human health. also observed increase in microbial contamination in each week because increase the moisture content for powdered milk. Can be used more than 3 weeks after opening if stored in good conditions with good hygienic practices during milk preparation.

scholarly journals Effect of Temperature during Drying and Storage of Dried Figs on Growth, Gene Expression and Aflatoxin Production

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 134
Author(s):  
Ana Isabel Galván ◽  
Alicia Rodríguez ◽  
Alberto Martín ◽  
Manuel Joaquín Serradilla ◽  
Ana Martínez-Dorado ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aflatoxin Production ◽  
Effect Of Temperature ◽  
Mycotoxin Production ◽  
Industrial Processing ◽  
Factors Associated ◽  
Different Temperatures ◽  
Major Producer ◽  
Main Factors ◽  
And Storage

Dried fig is susceptible to infection by Aspergillus flavus, the major producer of the carcinogenic mycotoxins. This fruit may be contaminated by the fungus throughout the entire chain production, especially during natural sun-drying, post-harvest, industrial processing, storage, and fruit retailing. Correct management of such critical stages is necessary to prevent mould growth and mycotoxin accumulation, with temperature being one of the main factors associated with these problems. The effect of different temperatures (5, 16, 25, 30, and 37 °C) related to dried-fig processing on growth, one of the regulatory genes of aflatoxin pathway (aflR) and mycotoxin production by A. flavus, was assessed. Firstly, growth and aflatoxin production of 11 A. flavus strains were checked before selecting two strains (M30 and M144) for in-depth studies. Findings showed that there were enormous differences in aflatoxin amounts and related-gene expression between the two selected strains. Based on the results, mild temperatures, and changes in temperature during drying and storage of dried figs should be avoided. Drying should be conducted at temperatures >30 °C and close to 37 °C, while industry processing, storage, and retailing of dried figs are advisable to perform at refrigeration temperatures (<10 °C) to avoid mycotoxin production.

scholarly journals Moxifloxacin Activates the SOS Response in Mycobacterium tuberculosis in a Dose- and Time-Dependent Manner

2021 ◽  
Vol 9 (2) ◽  
pp. 255
Author(s):  
Angelo Iacobino ◽  
Giovanni Piccaro ◽  
Manuela Pardini ◽  
Lanfranco Fattorini ◽  
Federico Giannoni
Keyword(s):  
Gene Expression ◽  
Mycobacterium Tuberculosis ◽  
Physiological State ◽  
Transcriptional Response ◽  
Sos Response ◽  
Resistant Mutant ◽  
Time Dependent ◽  
Dependent Manner ◽  
Gyra Gene ◽  
Drug Concentrations

Previous studies on Escherichia coli demonstrated that sub-minimum inhibitory concentration (MIC) of fluoroquinolones induced the SOS response, increasing drug tolerance. We characterized the transcriptional response to moxifloxacin in Mycobacterium tuberculosis. Reference strain H37Rv was treated with moxifloxacin and gene expression studied by qRT-PCR. Five SOS regulon genes, recA, lexA, dnaE2, Rv3074 and Rv3776, were induced in a dose- and time-dependent manner. A range of moxifloxacin concentrations induced recA, with a peak observed at 2 × MIC (0.25 μg/mL) after 16 h. Another seven SOS responses and three DNA repair genes were significantly induced by moxifloxacin. Induction of recA by moxifloxacin was higher in log-phase than in early- and stationary-phase cells, and absent in dormant bacilli. Furthermore, in an H37Rv fluoroquinolone-resistant mutant carrying the D94G mutation in the gyrA gene, the SOS response was induced at drug concentrations higher than the mutant MIC value. The 2 × MIC of moxifloxacin determined no significant changes in gene expression in a panel of 32 genes, except for up-regulation of the relK toxin and of Rv3290c and Rv2517c, two persistence-related genes. Overall, our data show that activation of the SOS response by moxifloxacin, a likely link to increased mutation rate and persister formation, is time, dose, physiological state and, possibly, MIC dependent.

scholarly journals Induction and Resuscitation of Viable but Nonculturable Corynebacterium diphtheriae

2021 ◽  
Vol 9 (5) ◽  
pp. 927
Author(s):  
Takashi Hamabata ◽  
Mitsutoshi Senoh ◽  
Masaaki Iwaki ◽  
Ayae Nishiyama ◽  
Akihiko Yamamoto ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Diphtheria Toxin ◽  
Pathogenic Bacteria ◽  
Corynebacterium Diphtheriae ◽  
Human Pathogen ◽  
Vbnc State ◽  
Viable But Nonculturable ◽  
Environmental Survival ◽  
Reverse Transcription Quantitative Pcr ◽  
Morphological Differences

Many pathogenic bacteria, including Escherichia coli and Vibrio cholerae, can become viable but nonculturable (VBNC) following exposure to specific stress conditions. Corynebacterium diphtheriae, a known human pathogen causing diphtheria, has not previously been shown to enter the VBNC state. Here, we report that C. diphtheriae can become VBNC when exposed to low temperatures. Morphological differences in culturable and VBNC C. diphtheriae were examined using scanning electron microscopy. Culturable cells presented with a typical rod-shape, whereas VBNC cells showed a distorted shape with an expanded center. Cells could be transitioned from VBNC to culturable following treatment with catalase. This was further evaluated via RNA sequence-based transcriptomic analysis and reverse-transcription quantitative PCR of culturable, VBNC, and resuscitated VBNC cells following catalase treatment. As expected, many genes showed different behavior by resuscitation. The expression of both the diphtheria toxin and the repressor of diphtheria toxin genes remained largely unchanged under all four conditions (culturable, VBNC, VBNC after the addition of catalase, and resuscitated cells). This is the first study to demonstrate that C. diphtheriae can enter a VBNC state and that it can be rescued from this state via the addition of catalase. This study helps to expand our general understanding of VBNC, the pathogenicity of VBNC C. diphtheriae, and its environmental survival strategy.

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