酰基-高丝氨酸内酯(AHL)对鼠伤寒沙门氏菌生物菌膜形成的影响

[目的]研究铜绿假单胞菌所产生的群体感应信号分子酰基-高丝氨酸内酯(AHL)对鼠伤寒沙门氏菌生物菌膜形成的影响,为不同菌体间群体感应的研究提供参考,为沙门氏菌的控制提供帮助。[方法]利用薄层层析法分析铜绿假单胞菌所产生AHL的成分,并通过添加0%、1.0%、1.5%、2.0%(体积分数)的AHL来研究其对鼠伤寒沙门氏菌生物菌膜形成、浮游菌体生长以及菌体泳动能力的影响。[结果]铜绿假单胞菌产生2种相同类型的AHL分子(C12-HSL和3-oxo-C8-HSL),100℃加热5 min并不会改变AHL的成分。当AHL添加量低于1.5%时,虽然浮游菌体指数生长时期受到一定抑制,但随着时间的延长,稳定期浮游菌体的生长并无显著差异,反观生物菌膜,其形成明显受到抑制。当AHL添加量达到2%时,浮游菌体生长和生物菌膜形成均受到显著抑制,说明AHL对鼠伤寒沙门氏菌生物菌膜的形成有明显抑制作用。AHL对单一菌体泳动性有显著抑制作用,而对群体泳动性有不同程度的促进作用。[结论]群体感应信号分子AHL对鼠伤寒沙门氏菌浮游菌体生长的影响受添加量调控,当AHL添加量增加到一定值时浮游菌体生长才受到抑制,但对生物菌膜的形成有明显抑制作用,且随着AHL添加量提高,抑制作用增强。

The staphylococcal nuclease prevents biofilm formation in Staphylococcus aureus and other biofilm-forming bacteria

The staphylococcal nuclease, encoded by the nucl gene, is an important virulence factor of Staphylococcus aureus. However, the physiological role of the nuclease has not been fully characterized. The current study observed that biofilm development could be prevented in staphylococcal nuclease-producing strains of S. aureus; however, when the nucl gene was knocked out, the ability to form a biofilm significantly increased. Scanning electron and confocal scanning laser microscopy were used to evaluate the role of the nucl gene in biofilm formation. Moreover, the nucl gene product, staphylococcal nuclease, and re- combinant NUC1 protein were found to have a visible effect on other biofilm-forming bacteria, such as Pseudomonas aeru- ginosa, Actinobacillus pleuropneurnoniae, and Haernophilus parasuis. The current study showed a direct relationship between staphylococcal nuclease production and the prevention of biofilm development. The findings from this study underscore the important role of staphylococcal nuclease activity to prevent biofilm formation in S. aureus. They also provided evidence for the biological role of staphylococcal nucleases in other organisms.