Physiological and Molecular Studies on Thermotolerance of Bacillus cereus Isolated from Some Dairy Products and Fast Foods

Gharib, Aham; El-Hamid, Marwa I. Abd; Ayob, Engy

doi:10.21608/zvjz.2020.35504.1113

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…Thermal resistance has been described in several studies about bacteria that contaminate food (2,13,16) . This thermal resistance is related to survival mechanisms of adaptive stress that increase the expression of heat shock-proteins that protect spore-forming cells (17) .…”

Section: Time Of Growth (Hours)mentioning

confidence: 99%

Assessment of temperature and acid tolerance of Bacillus subtilis isolated from a Brazilian fruit juice-added soy beverage

Oliveira

Amaral

Milagres

et al. 2021

INTER

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Bacillus subtilis is a spore-forming bacterium and an important food contaminant. The aim of this study was to analyze the ability of B. subtilis spores to survive under conditions of low pH and high temperature. The package was purchased at a local supermarket, in Uberaba, Minas Gerais. A sample was collected, diluted and plated on Brain-Heart-Infusion agar (BHI). After incubation, suspected colonies of B. subtilis were transferred to BHI agar. Cell morphology, the presence of spores and Gram stain were examined, and the isolate was identified by 16S rRNA gene sequencing . The microscope evaluation indicated the presence of spores. The thermal tolerance of the spores was evaluated by the addition of 3x109spores/mL in test tubes containing peptone water. Heat treatments were carried out at 80 and 90°C at different incubation times (0, 10, 20, 30, 40, 50 and 60 min). After heating, the tubes were cooled and the number of viable spores was determined in BHI Agar. For the analysis of spore survival, D and Z values were calculated. Tolerance to acid conditions was evaluated using BHI broth with different pH values. After incubation, the bacterial concentration was determined by determining viable cell count on BHI Agar medium. The vegetative cells were transferred to the BHI broth and the pH was adjusted to different values (3, 4 or 5). Sampling were taken 8, 12 and 24 h after incubation. The samples were serially diluted in peptone water and spread in BHI Agar to determine the viable cell count . The 16S rRNA gene sequencing indicated high similarity (99.99%) with B. subtilis. D values were 17.01 min at 80°C and 13.42 min at 90°C. The Z-value was 97.13°C. B. subtilis was not able to grow at pH 3 and pH 4, but its survival was confirmed after the growth of colonies on BHI agar. At pH 5, B. subtilis grew after 24 h and the final pH changed to 7. Our results suggest that the spores of B. subtilis isolated from fruit juice-added soy beverage are tolerant to low pH and high temperature.

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Section: Time Of Growth (Hours)mentioning

confidence: 99%

Assessment of temperature and acid tolerance of Bacillus subtilis isolated from a Brazilian fruit juice-added soy beverage

Oliveira

Amaral

Milagres

et al. 2021

INTER

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“…Mesophilic thermoduric bacteria have an optimum temperature of about 30 °C, however, they can grow in the range 5 to 50 °C. These include spore-forming and non-spore-forming bacteria as Bacillus, Enterococcus, Streptococcus, and Arthrobacter species, which can withstand harsh environments (1).…”

Section: Introductionmentioning

confidence: 99%

INCEDENCE OF THERMODURIC ANTIMICROBIAL-RESISTANT Bacillus AND Enterococcus SPECIES IN SOME DAIRY PRODUCTS

Elsaid,

Elshaer,

Bayoumi

2021

SVR

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Livestock meat is considered a potential source of human infection, therefore evaluation of the infection rate with Toxoplasma gondii (T. gondii) in these animals’ meat is needed for public health protection. Serum and meat samples were collected from slaughtered animals (n=106) (27 sheep, 42 cattle and 37 camels) from slaughterhouses in Aswan Governorate, located in southern Egypt. T. gondii infection status was detected by Latex agglutination test (LAT), microscopic examination and PCR. Our results revealed that the overall prevalence of anti-T. gondii antibodies among serum samples was 48.1 % using LAT. Male sheep, cattle, and camels had a higher positive percentage (42.9 %, 69.4% and 33.3 %, respectively) than females (40 %, 50 % and 30.8 %, respectively). The infection rate of T. gondii was higher in adult sheep and camels, while it was lower in adult cattle (64.5 %) than in young (72.7 %). There was a high statistically significant difference (P ≤ 0.01) between the animal species using LAT. T. gondii trophozoites were detected microscopically in 47.1 % of meat samples, while T. gondii DNA was detected in 56.9 % by using conventional Polymerase Chain Reaction (cPCR) based B1 gene. There was no significant difference between the results of both microscopy and PCR methods. In conclusion, PCR outperforms LAT in the detection of T. gondii infection and can thus be applied to routine diagnosis of toxoplasmosis in red meat producing animals.Key words: Aswan; camel ; cattle ; Egypt; LAT; PCR; red meat; sheep; Toxoplasma gondii

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Physiological and Molecular Studies on Thermotolerance of Bacillus cereus Isolated from Some Dairy Products and Fast Foods

Cited by 2 publications

References 26 publications

Assessment of temperature and acid tolerance of Bacillus subtilis isolated from a Brazilian fruit juice-added soy beverage

Assessment of temperature and acid tolerance of Bacillus subtilis isolated from a Brazilian fruit juice-added soy beverage

INCEDENCE OF THERMODURIC ANTIMICROBIAL-RESISTANT Bacillus AND Enterococcus SPECIES IN SOME DAIRY PRODUCTS

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