The relationship between biofilm formation and RpoS status was assessed in nine field isolates of C. sakazakii. Their ability to form biofilms was studied in BHI and minimum media with different pH values and supplemented or not with the amino acids arginine, lysine and glutamic acid. Biofilm formation, both on polystyrene and stainless steel, was measured by spectrometric determination of the fixed crystal violet and the biofilms were visualized by confocal laser scanning microscopy and scanning electron microscopy. Despite the existing heterogeneity among the different strains, biofilm formation was generally higher in buffered minimum media (pH 7.0) supplemented with lysine than in other culture media and on stainless steel plates than on polystyrene. The results showed a lower ability to form biofilms for a strain with a loss-of-function mutation in the rpoS gene, the general stress response regulator of Gram-negative bacteria, when compared to the rest of the strains, which harboured a functional rpoS. The complementation of this strain with a functional rpoS gene resulted in an increase in its biofilm formation ability up to levels comparable to those observed for strains with a functional rpoS. However, the differences were markedly reduced when the incubation time was increased from 24 to 48 h, indicating that the loss of RpoS caused a delay in the development of mature biofilms, rather than a complete inhibition of biofilm production in C. sakazakii.

生物膜形成和RpoS状态之间的关系进行了评估的九个阪崎肠杆菌的现场分离。在BHI和具有不同pH值并添加或不添加氨基酸精氨酸，赖氨酸和谷氨酸的基本培养基中，研究了它们形成生物膜的能力。通过分光光度法测定固定的结晶紫来测量在聚苯乙烯和不锈钢上的生物膜形成，并通过共聚焦激光扫描显微镜和扫描电子显微镜观察生物膜。尽管不同菌株之间存在异质性，但在添加了赖氨酸的缓冲最低培养基（pH 7.0）中，生物膜的形成通常要比其他培养基和不锈钢板上的生物膜形成要多于聚苯乙烯。结果表明，针对rpoS中功能缺失突变的菌株形成生物膜的能力较低与其他具有功能性rpoS的菌株相比，该基因是革兰氏阴性细菌的一般应激反应调节因子。该菌株与功能rpoS基因的互补导致其生物膜形成能力的增加，达到了与具有功能rpoS功能的菌株观察到的水平相当的水平。但是，当孵育时间从24小时增加到48小时时，差异显着减小，这表明RpoS的丢失导致成熟生物膜的发育延迟，而不是完全抑制了阪崎肠杆菌生物膜的产生。