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Abstract：
Listeria monocytogenes are Gram-positive rods, widespread in the environment due to their wide tolerance to changing conditions. The apilot study aimed to assess the impact of six various stresses (heat, cold, osmotic, acid, alkali, frozen) on phenotypic features: MIC of antibiotics (penicillin, ampicillin, meropenem, erythromycin, co-trimoxazole; gradient stripes), motility, ability to form a biofilm (crystal violet method) and growth rate (OD and quantitative method), expression level of sigB (stress induced regulator of genes), agrA, agrB (associated with biofilm formation) and lmo2230, lmo0596 (acid and alkali stress) (qPCR) for three strains of L. monocytogenes.
Applied stress conditions contributed to changes in phenotypic features and expression levels of sigB, agrA, agrB, lmo2230 and lmo0596. Stress exposure increased MIC value for penicillin (ATCC 19111 - alkaline stress), ampicillin (472CC - osmotic, acid, alkaline stress), meropenem (strains: 55 C - acid, alkaline, o smotic, frozen stress; 472CC - acid, alkaline stress), erythromycin (strains: 55 C - acid stress; 472CC - acid, alkaline, osmotic stress; ATCC 19111 - osmotic, acid, alkaline, frozen stress), co-trimoxazole (strains: 55 C - acid stress; ATCC 19111 - osmotic, acid, alkaline stress). These changes, however, did not affect antibiotic susceptibility. The strain 472CC (a moderate biofilm former) increased biofilm production after exposure to all stress factors except heat and acid. The ATCC 19111 (a weak producer) formed moderate biofilm under all studied conditions except cold and frozen stress, respectively. The strain 55 C became a strong biofilm producer after exposure to cold and produced a weak biofilm in response to frozen stress. Three tested strains had lower growth rate (compared to the no stress variant) after exposure to heat stress. It has been found that the sigB transcript level increased under alkaline (472CC) stress and the agrB expression increased under cold, osmotic (55 C, 472CC), alkali and frozen (472CC) stress. In contrast, sigB transcript level decreased in response to acid and frozen stress (55 C), lmo2230 transcript level after exposure to acid and alkali stress (ATCC 19111), and lmo0596 transcript level after exposure to acid stress (ATCC 19111).
Environmental stress changes the ability to form a biofilm and the MIC values of antibiotics and affect the level of expression of selected genes, which may increase the survival and virulence of L. monocytogenes. Further research on a large L. monocytogenes population is needed to assess the molecular mechanism responsible for the correlation of antibiotic resistance, biofilm formation and resistance to stress factors.
Applied stress conditions contributed to changes in phenotypic features and expression levels of sigB, agrA, agrB, lmo2230 and lmo0596. Stress exposure increased MIC value for penicillin (ATCC 19111 - alkaline stress), ampicillin (472CC - osmotic, acid, alkaline stress), meropenem (strains: 55 C - acid, alkaline, o smotic, frozen stress; 472CC - acid, alkaline stress), erythromycin (strains: 55 C - acid stress; 472CC - acid, alkaline, osmotic stress; ATCC 19111 - osmotic, acid, alkaline, frozen stress), co-trimoxazole (strains: 55 C - acid stress; ATCC 19111 - osmotic, acid, alkaline stress). These changes, however, did not affect antibiotic susceptibility. The strain 472CC (a moderate biofilm former) increased biofilm production after exposure to all stress factors except heat and acid. The ATCC 19111 (a weak producer) formed moderate biofilm under all studied conditions except cold and frozen stress, respectively. The strain 55 C became a strong biofilm producer after exposure to cold and produced a weak biofilm in response to frozen stress. Three tested strains had lower growth rate (compared to the no stress variant) after exposure to heat stress. It has been found that the sigB transcript level increased under alkaline (472CC) stress and the agrB expression increased under cold, osmotic (55 C, 472CC), alkali and frozen (472CC) stress. In contrast, sigB transcript level decreased in response to acid and frozen stress (55 C), lmo2230 transcript level after exposure to acid and alkali stress (ATCC 19111), and lmo0596 transcript level after exposure to acid stress (ATCC 19111).
Environmental stress changes the ability to form a biofilm and the MIC values of antibiotics and affect the level of expression of selected genes, which may increase the survival and virulence of L. monocytogenes. Further research on a large L. monocytogenes population is needed to assess the molecular mechanism responsible for the correlation of antibiotic resistance, biofilm formation and resistance to stress factors.
摘要：
背景：单核细胞增生李斯特菌是革兰氏阳性棒，由于它们对不断变化的条件具有广泛的耐受性，因此在环境中普遍存在。apilot研究旨在评估六种不同应力的影响(热，冷,渗透，酸,碱,冷冻)表型特征：抗生素的MIC(青霉素，氨苄青霉素,美罗培南,红霉素,复方新诺明；梯度条纹)，运动性,形成生物膜的能力（结晶紫方法）和生长速率（OD和定量方法），sigB（应激诱导基因调节因子）的表达水平，agrA,三个单核细胞增生李斯特菌菌株的agrB（与生物膜形成相关）和lmo2230，lmo0596（酸碱胁迫）（qPCR）。
结果：施加的应激条件有助于sigB的表型特征和表达水平的变化，agrA,agrB,lmo2230和lmo0596.压力暴露增加了青霉素的MIC值（ATCC19111-碱性压力），氨苄青霉素（472CC-渗透，酸,碱性应力)，美罗培南（菌株：55C-酸，碱性,oSmotic,冻结应力；472CC-酸，碱性应力)，红霉素（菌株：55C-酸胁迫；472CC-酸，碱性,渗透胁迫；ATCC19111-渗透，酸,碱性,冻结应力)，复方新诺明(菌株：55C-酸胁迫；ATCC19111-渗透，酸,碱性应力)。这些变化,然而,不影响抗生素敏感性。菌株472CC（中度生物膜形成剂）在暴露于除热和酸以外的所有胁迫因素后增加了生物膜的产生。ATCC19111（弱生产者）在所有研究条件下形成中等生物膜，除了寒冷和冰冻胁迫，分别。55°C的菌株在暴露于寒冷后成为强生物膜生产者，并响应于冷冻胁迫而产生弱生物膜。三种测试菌株在暴露于热胁迫后具有较低的生长速率(与无胁迫变体相比)。已经发现，在碱性（472CC）胁迫下，sigB转录物水平增加，而在寒冷条件下，agrB表达增加。渗透(55℃，472CC),碱和冷冻（472CC）胁迫。相比之下,SigB转录水平降低响应酸和冷冻应激（55℃），暴露于酸碱胁迫后的lmo2230转录水平（ATCC19111），和暴露于酸胁迫后的lmo0596转录物水平(ATCC19111)。
结论：环境胁迫改变了形成生物膜的能力和抗生素的MIC值，并影响了所选基因的表达水平，这可能会增加单核细胞增生李斯特菌的存活率和毒力。需要对大型单核细胞增生李斯特菌群体进行进一步研究，以评估负责抗生素耐药性相关性的分子机制。生物膜的形成和对应激因素的抗性。
结果：施加的应激条件有助于sigB的表型特征和表达水平的变化，agrA,agrB,lmo2230和lmo0596.压力暴露增加了青霉素的MIC值（ATCC19111-碱性压力），氨苄青霉素（472CC-渗透，酸,碱性应力)，美罗培南（菌株：55C-酸，碱性,oSmotic,冻结应力；472CC-酸，碱性应力)，红霉素（菌株：55C-酸胁迫；472CC-酸，碱性,渗透胁迫；ATCC19111-渗透，酸,碱性,冻结应力)，复方新诺明(菌株：55C-酸胁迫；ATCC19111-渗透，酸,碱性应力)。这些变化,然而,不影响抗生素敏感性。菌株472CC（中度生物膜形成剂）在暴露于除热和酸以外的所有胁迫因素后增加了生物膜的产生。ATCC19111（弱生产者）在所有研究条件下形成中等生物膜，除了寒冷和冰冻胁迫，分别。55°C的菌株在暴露于寒冷后成为强生物膜生产者，并响应于冷冻胁迫而产生弱生物膜。三种测试菌株在暴露于热胁迫后具有较低的生长速率(与无胁迫变体相比)。已经发现，在碱性（472CC）胁迫下，sigB转录物水平增加，而在寒冷条件下，agrB表达增加。渗透(55℃，472CC),碱和冷冻（472CC）胁迫。相比之下,SigB转录水平降低响应酸和冷冻应激（55℃），暴露于酸碱胁迫后的lmo2230转录水平（ATCC19111），和暴露于酸胁迫后的lmo0596转录物水平(ATCC19111)。
结论：环境胁迫改变了形成生物膜的能力和抗生素的MIC值，并影响了所选基因的表达水平，这可能会增加单核细胞增生李斯特菌的存活率和毒力。需要对大型单核细胞增生李斯特菌群体进行进一步研究，以评估负责抗生素耐药性相关性的分子机制。生物膜的形成和对应激因素的抗性。
