乳过氧化物酶系统对血型链球菌和变形链球菌生长的影响

Effects of lactoperoxidase system on the growth of Streptococcus sanguis and Streptococcus mutans

目的：探讨乳过氧化物酶系统在口腔微生态环境中对链球菌族生长和菌种平衡的影响。方法：将血型链球菌３４和变形链球菌Ｉｎｇｂｒｉｔ（ｃ）分为纯培养和混合培养等实验组，用连续培养方法，给予乳过氧化物酶（ＬＰＯ）、硫氰酸盐、Ｈ２Ｏ２，采用活菌计数法检测两菌的生长状态。结果：血型链球菌３４在参入乳过氧化物酶因素的培养液中，其生长量较为平稳，有较强的抵抗力，而变形链球菌的生长量显著下降；混合培养中两菌的生长量均有所提高。结论：两菌的共生可以提高它们对乳过氧化物酶系统的抵抗力；血形链球菌ＬＰＯ系统的高抵抗力与其在早期牙菌斑中占优势是相一致的。

Objective:To study the effects of lactoperoxidase system on the growth of streptococcus in contineous culture. Methods: S.sanguis 34 and S.mutans Ingbritt(c) were exposed to lactoperoxidase (LPO,2000 U/L),thiocyanate (1×10 -3 mol/L) and H 2O 2(1.6×10 -4 mol/L).The growth of the two strains in separate or mixed culture was investigated with bacteria counting,Results:At 0 and 20 h in separate cultures without LOP,the log number (per ml) of S.sanguis were 8.34±0.78 and 9.37±0.87 respectively,that of S.mutans 8.39±0.66 and 8.99±0.77;at 24 h and 36 h in the separate cultures with LOP,the log number of S.sanguis were 8.79±0.78 and 8.64±0.78,that of S.mutans 8.68±0.89 and 5.70±4.08.At 0 and 20 h in a mixed culture without LPO,the log number of S.sanguis were 8.57±0.67 and 9.08±0.90 respectively,that of S.mutans 7.91±0.98 and 8.85±0.89;at 24 h and 36 h in the mixed culture with LPO,the log number of S.sanguis were 8.61±1.17 and 8.58±0.92,that of S.mutans 8.33±1.01 and 7.64±0.53.Conclusion:The symbiosis of the two bacteria may enhance their resistance to LPO. S.sanguis is high resistant to hydrogen peroxide.