对氨基苯甲酸对变形链球菌生长影响的体外实验

Effects of Para-aminobenzoic Acid (PABA) on Growth of Streptococcus mutans

目的 :探讨不同浓度的对氨基苯甲酸 (PABA)对变链菌生长的影响。方法 :将变形链球菌ATCC2 5 175 (血清c型 )在改良Carlsson培养基中厌氧培养 ,实验组在其中加入不同浓度 (10 _1 0 ～ 10 _3 g L)的PABA液厌氧培养 48h后采用紫外可见分光光度仪测定细菌浓度OD值 (λ=5 5 0nm) ,并在琼脂平板上培养观察细菌生长情况 ,进行菌落计数。结果 :菌液比浊及菌落计数结果均表明PABA确有促进变链菌生长的能力 ,当PABA的浓度从 10 _1 0 ～ 10 _4g L增大时 ,其促进变链菌生长的能力增强 ,但当PABA浓度增大到 10 _3 g L ,则促进变链菌生长的能力开始下降。当PABA浓度为 10 _9～ 10 _3 g L时 ,实验组的细菌生长明显高于对照组 (P <0 0 5 )。结论 :当PABA的浓度为 10 _4g L时 ,其促进变链菌生长的能力达最强 ,高于或低于此浓度 。

Objective:The aim of this study is to examine effects of para_aminobenzoic acid (PABA) on the growth of Streptococcus mutans (S.mutans).Methods:Different concentrations of PABA (10\+\{_10\}～10\+\{_3\} g/L) were separately transferred to modified Carlsson medium. S. mutans (ATCC 25175) grew in modified Carlsson medium with different concentrations of PABA. All cultures were incubated at 37℃ anaerobically in an atmosphere of 80% of nitrogen (v/v), 10% of hydrogen (v/v) and 10% of carbon dioxide (v/v) for 48 hours. The absorbance values of S. mutans were measured by using a spectrometer (UV_1601). The colony forming units (CFU) were obtained by growing S. mutans in media with different concentrations of PABA (10\+\{_10\}～10\+\{_3\} g/L).Results:Different concentrations of PABA had different stimulating effects on the growth of S. mutans (P<0.05). But this kind of stimulating effects declined when the concentration of PABA was 10\+\{_3\}g/L.Conclusion:This experiment indicates PABA has stimulating effects on the growth of S. mutans, and PABA can promote growth of S. mutans.\;