Parvimonas micra is frequently isolated from lesions of apical periodontitis and is a major disease-related pathogen. One of the main causes of apical periodontitis is extraradicular biofilm. In this study, we investigated polymicrobial biofilm formation by P. micra and species associated with apical periodontitis. The coaggregation activity of P. micra with partner strains was investigated by visual assays. Synergistic biofilm formation was evaluated by cocultures of P. micra and partner strains. Growth of planktonic cells was measured by evaluating the absorbance at OD₆₆₀, and biofilm formation was examined by staining with crystal violet. The effects of soluble components on synergistic biofilm formation and planktonic cell growth were examined after coculture of P. micra and other strains separated with a 0.4-μm pore-size porous membrane.

P. micra coaggregated with Fusobacterium nucleatum, Porphyromonas gingivalis, or Capnoctyophaga ochracea. P. micra showed no coaggregation with Staphylococcus aureus, S. epidermidis, or Prevotella intermedia. In mixed cultures, biofilm formation by P. micra and F. nucleatum was greater than that by P. micra and P. gingivalis or C. ochracea. In separated cocultures, planktonic cell growth of P. micra was enhanced by each of the three species. Biofilm formation by P. micra was enhanced by F. nucleatum or C. ochracea; however, no significant enhancement was observed with P. gingivalis.

These data indicated that P. micra and F. nucleatum had synergistic effects in biofilm formation and that these effects may be important for colonization by these two species in apical periodontitis lesions.

Parvimonas micra通常是从根尖周炎的病变中分离出来的，是一种与疾病相关的主要病原体。根尖周膜炎的主要原因之一是放射状生物膜。在这项研究中，我们调查了P. micra和与根尖周炎相关的物种形成的微生物生物膜。通过视觉测定研究了P. micra与伴侣菌株的共聚集活性。通过P. micra和伴侣菌株的共培养评估协同生物膜的形成。通过评估OD ₆₆₀的吸光度来测量浮游细胞的生长，并用结晶紫染色检查生物膜的形成。共培养P. micra和其他用0.4μm孔径的多孔膜分离的菌株后，检查了可溶性成分对协同生物膜形成和浮游细胞生长的影响。

P. micra与核梭状芽胞杆菌，齿龈卟啉单胞菌或och形衣原体共聚集。P. micra与金黄色葡萄球菌，表皮葡萄球菌或中间肠杆菌均无聚集。在混合培养物，由生物膜形成P. MICRA和具核梭杆菌比由更大P. MICRA和牙龈或C. ochracea。在分离的共培养物中，三个物种中的每一个都增强了P. micra浮游细胞的生长。P. micra的生物膜形成通过F.核或C. ochracea ; 但是，牙龈卟啉单胞菌未观察到明显的增强作用。

这些数据表明，P. MICRA和具核梭杆菌具有在生物膜的形成，并且这些效果可以是用于通过这两个物种中根尖周病变定植重要的协同效应。