scholarly journals Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance

2021 ◽  
Vol 9 (2) ◽  
pp. 403
Author(s):  
Angela Ma ◽  
Norman Neumann ◽  
Linda Chui
Keyword(s):  
Food Safety ◽  
Heat Resistance ◽  
Food Processing ◽  
Biofilm Formation ◽  
Thermal Inactivation ◽  
Inoculum Size ◽  
Genetic Determination ◽  
E Coli ◽  
Heat Resistant

Despite the effectiveness of thermal inactivation processes, Escherichiacoli biofilms continue to be a persistent source of contamination in food processing environments. E. coli strains possessing the locus of heat resistance are a novel food safety threat and raises the question of whether these strains can also form biofilms. The objectives of this study were to determine biofilm formation in heat resistant E. coli isolates from clinical and environmental origins using an in-house, two-component apparatus and to characterize biofilm formation-associated genes in the isolates using whole genome sequencing. Optimal conditions for biofilm formation in each of the heat resistant isolates were determined by manipulating inoculum size, nutrient concentration, and temperature conditions. Biofilm formation in the heat resistant isolates was detected at temperatures of 24 °C and 37 °C but not at 4 °C. Furthermore, biofilm formation was observed in all environmental isolates but only one clinical isolate despite shared profiles in biofilm formation-associated genes encoded by the isolates from both sources. The circulation of heat resistant E. coli isolates with multi-stress tolerance capabilities in environments related to food processing signify that such strains may be a serious food safety and public health risk.

Heat Resistance of Escherichia coli in Cow and Buffalo Milk

1980 ◽  
Vol 43 (5) ◽  
pp. 376-380 ◽  
Author(s):  
R. S. SINGH ◽  
B. RANGANATHAN
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Resistance ◽  
Skim Milk ◽  
Buffalo Milk ◽  
Time Interval ◽  
E Coli ◽  
Heat Resistant ◽  
Whole Milk

Three Escherichia coli cultures (0111:B4, 0127:B8 and NP) were selected to study their heat-resistant characteristics when in cow skim, cow whole and buffalo whole milk. The temperatures of heat-treatment included in this study were 50, 55, 60 and 63 C. The time interval during heat-treatment was 10 min at 50 and 55 C and 5 min at 60 and 63 C. Marked differences in heat-resistance were observed in the three E. coli cultures. The z-values obtained for strain 0111:B4 were 8.3, 9.0 and 10.2 when tested in cow skim milk, cow whole milk and buffalo milk, respectively. The z-values for 0127:B8 and NP were 17.5, 18.0 and 19.2 and 18.8, 19.0 and 20.3, respectively, for the three types of milk.

scholarly journals Facultative Anaerobes Shape Multispecies Biofilms Composed of Meat Processing Surface Bacteria and Escherichia coli O157:H7 or Salmonella enterica Serovar Typhimurium

2019 ◽  
Vol 85 (17) ◽  
Author(s):  
Jeyachchandran Visvalingam ◽  
Hui Wang ◽  
Tim C. Ells ◽  
Xianqin Yang
Keyword(s):  
Food Processing ◽  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Single Species ◽  
Meat Processing ◽  
Content Type ◽  
E Coli ◽  
Facultative Anaerobes ◽  
Serovar Typhimurium ◽  
Multispecies Biofilms

ABSTRACT This study investigated the microbial dynamics in multispecies biofilms of Escherichia coli O157:H7 strain 1934 (O157) or Salmonella enterica serovar Typhimurium ATCC 14028 (ST) and 40 strains of meat processing surface bacteria (MPB). Biofilms of O157 or ST with/without MPB were developed on stainless steel coupons at 15°C for up to 6 days. Bacteria in suspensions (inoculum, days 2 and 6) and biofilms (days 2 and 6) were enumerated by plating. The composition of multispecies cultures was determined by 16S rRNA gene sequencing. In suspensions, levels of O157 and ST were ∼2 log higher in single-species than in multispecies cultures on both sampling days. ST was 3 log higher in single-species than in multispecies biofilms. A similar trend, though to a lesser extent, was observed for O157 in biofilms on day 2 but not on day 6. No difference (P > 0.05) in bacterial counts was noted for the two MPB-pathogen cocultures at any time during incubation. Bacterial diversity in multispecies cultures decreased with incubation time, irrespective of the pathogen or culture type. The changes in the relative abundance of MPB were similar for the two MPB-pathogen cocultures, though different interbacterial interactions were noted. Respective fractions of ST and O157 were 2.1% and 0.97% initially and then 0.10% and 0.07% on day 2, and 0.60% and 0.04% on day 6. The relative proportions of facultative anaerobes in both multispecies cultures were greater in both suspensions and biofilms than in the inoculum. Citrobacter, Hafnia, Aeromonas, and Carnobacterium predominated in biofilms but not always in the planktonic cultures. IMPORTANCE Results of this study demonstrate that Salmonella enterica serovar Typhimurium and E. coli O157:H7 can integrate into biofilms when cocultured with bacteria from meat plant processing surfaces. However, the degree of biofilm formation for both pathogens was substantially reduced in the presence of the competing microbiota, with S. Typhimurium more greatly affected than E. coli O157:H7. The expression of extracellular determinants such as curli and cellulose appears to be less important for biofilm formation of the pathogens in multispecies cultures than in monoculture. In contrast to previous reports regarding food processing surface bacteria, data collected here also demonstrate that facultative anaerobes may have a competitive edge over strict aerobes in establishing multispecies biofilms. It would be important to take into account the presence of background bacteria when evaluating the potential persistence of a pathogen in food processing facilities.

scholarly journals Heat Resistance Mediated by pLM58 Plasmid-Borne ClpL in Listeria monocytogenes

mSphere ◽  
2017 ◽  
Vol 2 (6) ◽  
Author(s):  
Anna Pöntinen ◽  
Mariella Aalto-Araneda ◽  
Miia Lindström ◽  
Hannu Korkeala
Keyword(s):  
Listeria Monocytogenes ◽  
Food Safety ◽  
Heat Resistance ◽  
High Temperatures ◽  
Phenotypic Characterization ◽  
Severe Illness ◽  
Content Type ◽  
Potential Predictor ◽  
Heat Resistant ◽  
Genetic Mechanisms

ABSTRACT Listeria monocytogenes is a dangerous food pathogen causing the severe illness listeriosis that has a high mortality rate in immunocompromised individuals. Although destroyed by pasteurization, L. monocytogenes is among the most heat-resistant non-spore-forming bacteria. This poses a risk to food safety, as listeriosis is commonly associated with ready-to-eat foods that are consumed without thorough heating. However, L. monocytogenes strains differ in their ability to survive high temperatures, and comprehensive understanding of the genetic mechanisms underlying these differences is still limited. Whole-genome-sequence analysis and phenotypic characterization allowed us to identify a novel plasmid, designated pLM58, and a plasmid-borne ATP-dependent protease (ClpL), which mediated heat resistance in L. monocytogenes. As the first report on plasmid-mediated heat resistance in L. monocytogenes, our study sheds light on the accessory genetic mechanisms rendering certain L. monocytogenes strains particularly capable of surviving high temperatures—with plasmid-borne ClpL being a potential predictor of elevated heat resistance. Listeria monocytogenes is one of the most heat-resistant non-spore-forming food-borne pathogens and poses a notable risk to food safety, particularly when mild heat treatments are used in food processing and preparation. While general heat stress properties and response mechanisms of L. monocytogenes have been described, accessory mechanisms providing particular L. monocytogenes strains with the advantage of enhanced heat resistance are unknown. Here, we report plasmid-mediated heat resistance of L. monocytogenes for the first time. This resistance is mediated by the ATP-dependent protease ClpL. We tested the survival of two wild-type L. monocytogenes strains—both of serotype 1/2c, sequence type ST9, and high sequence identity—at high temperatures and compared their genome composition in order to identify genetic mechanisms involved in their heat survival phenotype. L. monocytogenes AT3E was more heat resistant (0.0 CFU/ml log10 reduction) than strain AL4E (1.4 CFU/ml log10 reduction) after heating at 55°C for 40 min. A prominent difference in the genome compositions of the two strains was a 58-kb plasmid (pLM58) harbored by the heat-resistant AT3E strain, suggesting plasmid-mediated heat resistance. Indeed, plasmid curing resulted in significantly decreased heat resistance (1.1 CFU/ml log10 reduction) at 55°C. pLM58 harbored a 2,115-bp open reading frame annotated as an ATP-dependent protease (ClpL)-encoding clpL gene. Introducing the clpL gene into a natively heat-sensitive L. monocytogenes strain (1.2 CFU/ml log10 reduction) significantly increased the heat resistance of the recipient strain (0.4 CFU/ml log10 reduction) at 55°C. Plasmid-borne ClpL is thus a potential predictor of elevated heat resistance in L. monocytogenes. IMPORTANCE Listeria monocytogenes is a dangerous food pathogen causing the severe illness listeriosis that has a high mortality rate in immunocompromised individuals. Although destroyed by pasteurization, L. monocytogenes is among the most heat-resistant non-spore-forming bacteria. This poses a risk to food safety, as listeriosis is commonly associated with ready-to-eat foods that are consumed without thorough heating. However, L. monocytogenes strains differ in their ability to survive high temperatures, and comprehensive understanding of the genetic mechanisms underlying these differences is still limited. Whole-genome-sequence analysis and phenotypic characterization allowed us to identify a novel plasmid, designated pLM58, and a plasmid-borne ATP-dependent protease (ClpL), which mediated heat resistance in L. monocytogenes. As the first report on plasmid-mediated heat resistance in L. monocytogenes, our study sheds light on the accessory genetic mechanisms rendering certain L. monocytogenes strains particularly capable of surviving high temperatures—with plasmid-borne ClpL being a potential predictor of elevated heat resistance.

Understanding of food biofilms by the application of omics techniques

2021 ◽  
Author(s):  
Lei Yuan ◽  
Fedrick C Mgomi ◽  
Zhenbo Xu ◽  
Ni Wang ◽  
Guoqing He ◽  
...  
Keyword(s):  
Food Safety ◽  
Foodborne Pathogens ◽  
Food Processing ◽  
Biofilm Formation ◽  
Food Industry ◽  
Processing Conditions ◽  
Protective Barrier ◽  
And Control

Biofilms constitute a protective barrier for foodborne pathogens to survive under stressful food processing conditions. Therefore, studies into the development and control of biofilms by novel techniques are vital for the food industry. In recent years, foodomics techniques have been developed for biofilm studies, which contributed to a better understanding of biofilm behavior, physiology, composition, as well as their response to antibiofilm methods at different molecular levels including genes, RNA, proteins and metabolic metabolites. Throughout this review, the main studies where foodomics tools used to explore the mechanisms for biofilm formation, dispersal and elimination were reviewed. The data summarized from relevant studies are important to design novel and appropriate biofilm elimination methods for enhancing food safety at any point of food processing lines.

scholarly journals Male-Specific Coliphages as Indicators of Thermal Inactivation of Pathogens in Biosolids

2006 ◽  
Vol 72 (4) ◽  
pp. 2471-2475 ◽  
Author(s):  
Sharon P. Nappier ◽  
Michael D. Aitken ◽  
Mark D. Sobsey
Keyword(s):  
Anaerobic Digestion ◽  
Heat Resistance ◽  
Municipal Wastewater ◽  
Thermal Inactivation ◽  
Wastewater Sludge ◽  
Group Iii ◽  
Heat Resistant ◽  
Thermophilic Anaerobic Digestion ◽  
Group I ◽  
Male Specific

ABSTRACT Male-specific (F+) coliphages have been proposed as a candidate indicator of fecal contamination and of virus reduction in waste treatment. However, in this and earlier work with a laboratory thermophilic anaerobic digester, a heat-resistant fraction of F+ coliphage populations indigenous to municipal wastewater and sludge was evident. We therefore isolated coliphages from municipal wastewater sludge and from biosolid samples after thermophilic anaerobic digestion to evaluate the susceptibility of specific groups to thermal inactivation. Similar numbers of F+ DNA and F+ RNA coliphages were found in untreated sludge, but the majority of isolates in digested biosolids were group I F+ RNA phages. Separate experiments on individual isolates at 53°C confirmed the apparent heat resistance of group I F+ RNA coliphages as well as the susceptibility of group III F+ RNA coliphages. Although few F+ DNA coliphages were recovered from the treated biosolid samples, thermal inactivation experiments indicated heat resistance similar to that of group I F+ RNA phages. Hence, F+ DNA coliphage reductions during thermophilic anaerobic digestion are probably related to mechanisms other than thermal inactivation. Further studies should focus on the group III F+ RNA coliphages as potential indicators of reductions of heat-resistant pathogens in thermal processes for sludge treatment.

Thermal Inactivation of Escherichia coli O157:H7 Isolated from Ground Beef and Bovine Feces, and Suitability of Media for Enumeration

1998 ◽  
Vol 61 (3) ◽  
pp. 285-289 ◽  
Author(s):  
M. ROCELLE S. CLAVERO ◽  
LARRY R. BEUCHAT ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Treatment Temperature ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Polyethylene Bags ◽  
D Values ◽  
Bovine Feces

Rates of thermal inactivation of five strains of Escherichia coli O157:H7 isolated from ground beef implicated in outbreaks of hemorrhagic colitis and five strains isolated from bovine feces were determined. Ground beef (22% fat, 10 g), inoculated with individual test strains at populations ranging from 6.85 to 7.40 log10 CFU g−1 of beef, was formed into patties (0.3 cm thick and 8.0 cm in diameter) and sealed in polyethylene bags. For each strain and treatment temperature (54.4, 58.9, 62.8, 65.6, or 68.3°C), 6 bags were simultaneously immersed into a recirculating water bath. Viable cells in patties heated for various lengths of time were enumerated by plating diluted samples on sorbitol MacConkey agar supplemented with 4-methylumbelliferyl-β-d-glucuronide (MSMA) and modified eosin methylene blue (MEMB) agar. Regardless of strain or treatment temperature, higher numbers of E. coli O157:H7 cells were generally recovered on MEMB agar than on MSMA, indicating the inferiority of MSMA as a recovery medium for quantitative determination of E. coli O157:H7 cells in heat-processed ground beef. Significantly (P ≤ 0.05) higher D values when enumeration was done using MEMB agar compared with MSMA. Mean D values for combined strain data at 54.4, 58.9, 62.8, and 65.6°C from cultures on MEMB agar were 123.90, 6.47, 0.62, and 0.20 min, respectively, whereas D values of 25.5, 5.21, 0.57, and 0.18 min were obtained at the same temperatures from cultures on MSMA. Results suggest that cooking ground beef patties to an internal temperature of 68.3°C for 40 s will inactivate at least 99.99% of E. coli O157:H7 cells; z values of 4.0 and 5.1°C were calculated from mean D values obtained from MEMB agar and MSMA, respectively, as recovery media. Differences in D values and z values existed among strains but rates of thermal inactivation do not appear to be correlated with the sources of the isolates.

scholarly journals Mixed Biofilm Formation by Shiga Toxin–Producing Escherichia coli and Salmonella enterica Serovar Typhimurium Enhanced Bacterial Resistance to Sanitization due to Extracellular Polymeric Substances†

2013 ◽  
Vol 76 (9) ◽  
pp. 1513-1522 ◽  
Author(s):  
RONG WANG ◽  
NORASAK KALCHAYANAND ◽  
JOHN W. SCHMIDT ◽  
DAYNA M. HARHAY
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Foodborne Pathogens ◽  
Shiga Toxin ◽  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Bacterial Resistance ◽  
Salmonella Enterica Serovar Typhimurium ◽  
E Coli ◽  
Serovar Typhimurium

Shiga toxin–producing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium are important foodborne pathogens capable of forming single-species biofilms or coexisting in multispecies biofilm communities. Bacterial biofilm cells are usually more resistant to sanitization than their planktonic counterparts, so these foodborne pathogens in biofilms pose a serious food safety concern. We investigated how the coexistence of E. coli O157:H7 and Salmonella Typhimurium strains would affect bacterial planktonic growth competition and mixed biofilm composition. Furthermore, we also investigated how mixed biofilm formation would affect bacterial resistance to common sanitizers. Salmonella Typhimurium strains were able to outcompete E. coli strains in the planktonic growth phase; however, mixed biofilm development was highly dependent upon companion strain properties in terms of the expression of bacterial extracellular polymeric substances (EPS), including curli fimbriae and exopolysaccharide cellulose. The EPS-producing strains with higher biofilm-forming abilities were able to establish themselves in mixed biofilms more efficiently. In comparison to single-strain biofilms, Salmonella or E. coli strains with negative EPS expression obtained significantly enhanced resistance to sanitization by forming mixed biofilms with an EPS-producing companion strain of the other species. These observations indicate that the bacterial EPS components not only enhance the sanitizer resistance of the EPS-producing strains but also render protections to their companion strains, regardless of species, in mixed biofilms. Our study highlights the potential risk of cross-contamination by multispecies biofilms in food safety and the need for increased attention to proper sanitization practices in food processing facilities.

scholarly journals Heat Resistance in Escherichia coli and its Implications on Ground Beef Cooking Recommendations in Canada

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
X. Yang ◽  
F. Tran ◽  
M. Klasse
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Growth Medium ◽  
Thermal Characteristics ◽  
Ground Beef ◽  
Coli Strain ◽  
E Coli ◽  
Log Reduction ◽  
Heat Resistant ◽  
Resistant Strains

ObjectivesRecent reports of an extremely heat resistant but non-pathogenic beef Escherichia coli strain, AW 1.7, raised concerns over the adequacy of cooking ground beef to 71°C in Canada. The objective of this study was to assess the adequacy of the current cooking recommendations for ground beef in relation to heat resistant E. coli.Materials and MethodsIn total, 8 potentially heat resistant E. coli strains (4 generic and 4 E. coli O157:H7) from beef along with E. coli AW1.7 were included in this study. Heat resistance of the strains was first evaluated by decimal reductions at 60°C (D60°C-value), the time required to have a log reduction of the bacterial population at 60°C. The more heat resistant strains of each group (E. coli 62 and 68, and E. coli O157 J3 and C37) were further assessed for their heat resistance when grown in Lennox Broth without salt (LB-NS), LB + 2% NaCl and Meat Juice (MJ). Then, the two most heat resistant E. coli O157 strains (J3 and C37) and E. coli AW 1.7 were each introduced to extra lean ground beef (100 g) in vacuum pouches for determination of their D-values at three temperatures, 54, 57, and 60°C, from which a z-value for each strain was derived. The thermal characteristics of all three strains were fed into a predictive model to determine the process lethality of cooking burgers to 71°C with resting for up to 5 min. Finally, inactivation of the most heat resistant E. coli strain AW1.7, assessed in this study and reported in the literature, in ground beef was validated by grilling burgers containing 6.20 ± 0.24 log CFU/g of the organism to 71°C without or with a resting of 3 or 5 min.ResultsThe D60°C-values for these strains varied from 1.3 to 9.0 min, with J3 and AW1.7 being the least and most heat resistant strains, respectively. The D60°C-values for E. coli 62 and 68 were similar and were not affected by growth medium, while the heat resistance of C37, J3 and AW1.7 varied with the growth medium. When heated in extra lean ground beef (100 g) in vacuum pouches, the mean D54°C, D57°C, and D60°C-values were 44.8, 18.6 and 2.9 min for C37, 13.8, 6.9 and 0.9 min for J3, and 40.5, 9.1 6.1 min for AW1.7. The derived z- and D71°C-values were, respectively, 5.0, 5.1 and 7.3°C; and 0.022, 0.008, and 0.156 min. Burger temperatures continued to rise after being removed from heat when the target temperature was reached, by up to 5°C, and resting of 1 min would result in a destruction of 133, 374, and 14 log C37, J3 and AW1.7, estimated from process lethality. When burgers inoculated with AW1.7 were cooked to 71°C, 14 of the 15 burgers yielded no E. coli, while the 15th had a reduction of 4.5 log. Additional resting of 3 or 5 min resulted in complete elimination of AW 1.7.ConclusionIt has been predicted that 2% of E. coli from beef may carry heat resistant genes. The findings in this study, along with the very low level of total E. coli expected in ground beef in Canada, suggest that cooking ground beef to 71°C should be adequate to ensure the safety of such products.

scholarly journals Isolation of Anti-Escherichia coli O157:H7 Bacteriophages and Determination of Their Host Ranges

2018 ◽  
Vol 6 (9) ◽  
pp. 1200 ◽  
Author(s):  
Zeliha Yıldırım ◽  
Tuba Sakin ◽  
Fatma Çoban
Keyword(s):  
Escherichia Coli ◽  
Food Processing ◽  
Stream Water ◽  
Escherichia Coli O157 ◽  
Fish Farms ◽  
E Coli ◽  
Food Animal ◽  
Processing Plants ◽  
Raw Foods

The aim of this study was to isolate, purify and determine host ranges of bacteriophages infecting Escherichia coli O157:H7 from different environment such as river/stream water, sewage, raw food, animal troughs, wastewaters of food processing plants, slaughterhouse and fish farms. For screening of E. coli O157:H7 bacteriophages, 92 samples were used. It was found that in respect to anti-E. coli O157:H7 bacteriophages, food processing wastewaters, sewage and slaughterhouse wastewaters are the richest sources, and streams, troughs and fisheries wastewater are rich in the middle, and raw foods were the poorest source. A total of 37 phages were isolated and purified. The phages counts of the purified samples were changed among 30×103 - 34×108 PFU/mL. The isolated phages were generally infective against E. coli O157:H7 and E. coli strains and 81.08% of the phages (30 out of 37) formed clear plaques and were capable to lyse at least 1 out of 5 E. coli O157:H7 strains. In addition to E. coli, some phages were capable to infect some Salmonella enterica serovars. This results show that inhibitor spectra of the phages were wide.

Screening of Infectious Causes of Diarrhea and Genetic Determination of Diarrheagenic E. coli using Multiplex PCR in under 5 Years Children in Egypt

2020 ◽  
Vol EJMM29 (4) ◽  
pp. 27-34
Author(s):  
Yosra M. Hassan ◽  
Saha r M. Khairat ◽  
Nada N. Nawar ◽  
Maha M. Gaafar ◽  
Dina M Hassan ◽  
...  
Keyword(s):  
Multiplex Pcr ◽  
Infectious Diarrhea ◽  
Genetic Determination ◽  
E Coli ◽  
Single Positive ◽  
Life Threatening ◽  
Stool Specimens ◽  
Genetically Determined ◽  
Microbiological Procedures

Background: Infectious diarrhea represents a life-threatening problem among children in developing countries. Objectives: This work aimed to study bacterial, viral and parasitic causes of acute diarrhea; with genetic determination of diarrheagenic E. coli (DEC) in <5 years children. Methodology: Stool specimens were collected from 206 diarrheal children. Bacterial agents were isolated and identified by standard microbiological procedures. Multiplex PCR was done for genetic determination of DEC subtypes. ELISA was used for detection of viral and parasitic agents. Results: Stool specimens with at least single positive enteropathogen accounted for 98.5% with bacterial, viral and parasitic rates of 98.5%, 42.7% and 25.2%, respectively. Isolated bacteria were DEC (98.5%); Campylobacter (14%), Shigella (3.8%) and Salmonella (1.4%). Rota and Noroviruses showed prevalence of 32.5% and 5.3%, respectively. Conclusion: Infectious diarrhea were mostly due to bacterial agents. DEC and Campylobacter were predominant. EAEC and EPEC were the most genetically determined DEC subtypes.

Sign in / Sign up

Export Citation Format

Share Document