Full
Outline
To investigate the effects of the betA and betB genes on stress resistance and virulence of Cronobacter.
Using Cronobacter sakazakii as the experimental subject, this study emplored betA, betB,and betAB gene knockout and restoration strains to invesitage the effects of betA and betB on biofilm formation ability, stress resistance and cellular virulence of Cronobacter.
The biofilm formation ability of each strain was detected, and found that deletion of betA and betB led to a decrease of biofilm formation. It was speculated that betA and betB promote biofilm formation in Cronobacter by controlling betaine synthesis. The effects of different temperatures and pH on Cronobacter were examined using fluorescence microscopy and flow cytometry. The results showed that under high temperature and acidic conditions, the survival rates of all Cronobacter strains decreased.Specifically, survival rates at pH 7 and pH 9 were significantly higher than at pH 5 (P<0.05), and survival rates at 48 ℃ were significantly lower than at 25 ℃ and 37 ℃ (P<0.05). The assessment of Cronobacter virullence in cell infection revealed that bacterial infection was led to changes in the levels of tight junction proteins within cells, for the CS 34, ΔbetB, ΔbetAB, cpbetA, cpbetB and cpbetAB strains caused significantly greater damage to cells after drying treatment compared to before drying, resulting in a decrease in cell viability and leading to a significant decrease in tight junction-associated proteins (P<0.01). When the betA gene was deleted, desiccated Cronobacter did not cause a significant decrease in cell viability compared to non-desiccated bacteria.
This study finds that deletion of the betA and betB genes weakens the biofilm formation ability of Cronobacter and reduces its tolerance to acid and high temperature. It is also observed that when the betA gene is present, bacteria that survive under desiccated conditions tend to have stronger virulence and cause greater cellular damage.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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