Laible N J, Germaine G R
Infect Immun. 1982 Apr;36(1):148-59. doi: 10.1128/iai.36.1.148-159.1982.
Several strains of Streptococcus sanguis, Streptococcus mutans, Streptococcus mitis, Actinomyces viscosus, and Actinomyces naeslundii plus fresh isolates of Streptococcus salivarius were surveyed for their abilities to deplete lysozyme from human-whole-saliva supernatant. Bacteria were incubated in saliva for 60 min at 37 degrees C and then removed by centrifugation, and the recovered supernatant solutions were assayed for lysozyme activity by using whole cells of Micrococcus lysodeikticus as the substrate. Mean lysozyme depletions by bacterial strains varied over a wide (eightfold) range. The greatest mean depletion of lysozyme (60 to 70%) was observed with S. sanguis (biotype I), serotype b of S. mutans, and the fresh S. salivarius isolates. The lowest mean depletion was noted with S. mitis (15%) and biotype II S. sanguis (ca. 30%). The remaining species and strains exhibited an intermediate degree of depletion. In studies with S. sanguis 903, lysozyme was depleted by normal or heated (90 degrees C, 30 min) bacteria and could be recovered from the organism. Furthermore, under appropriate conditions, lysozyme depletion by cells at 0 and 37 degrees C was very similar. On the basis of these observations, we concluded that depletion was due to the adsorption of lysozyme by the organism. With S. sanguis 903, lysozyme adsorption depended on the concentration of bacteria, time of incubation, and the ionic strength of the medium. The extent of adsorption, however, was independent of pH's of 3.9 to 8.3. When a low concentration of S. sanguis 903 was used, lysozyme adsorption reached saturation (4 mug of adsorbed lysozyme per 10(7) cells) at 20 mug of lysozyme added per ml. Salivary lysozyme adsorption by several other oral microorganisms (A. viscosus WVU 626 and WVU 627, S. sanguis 73x11, S. mutans BHT, and S. salivarius NG) was similar to that of S. sanguis 903 in sensitivity to ionic strength. Lysozyme adsorption by S. sanguis 903 from either a buffer solution or a saliva supernatant was more sensitive to ionic strength at 0 than at 37 degrees C. On the basis of results from experiments in saliva versus buffer, we concluded that saliva had no major effect on the extent of lysozyme adsorption by S. sanguis 903 other than providing a source of ionic strength. A comparison of pH and ionic strength effects on lysozyme adsorption by S. sanguis 903 with literature reports of lysozyme lysis of whole cells and hydrolysis of cell walls, peptidoglycan, and (GlcNAc)(4) suggested that adsorption by S. sanguis 903 was more dependent on electrostatic interactions than was lysozyme catalysis. The possibility is discussed that anionic bacterial surface components mediate lysozyme adsorption and temper the potential effects of lysozyme on the microorganisms.
对几种血链球菌、变形链球菌、缓症链球菌、黏性放线菌、内氏放线菌菌株以及唾液链球菌的新鲜分离株进行了研究，以考察它们从人全唾液上清液中消耗溶菌酶的能力。将细菌在唾液中于37℃孵育60分钟，然后通过离心去除，回收的上清液用溶壁微球菌全细胞作为底物测定溶菌酶活性。各菌株对溶菌酶的平均消耗程度在很大范围内（八倍）变化。血链球菌（生物型I）、变形链球菌血清型b以及唾液链球菌新鲜分离株对溶菌酶的平均消耗最大（60%至70%）。缓症链球菌的平均消耗最低（15%），血链球菌生物型II的平均消耗约为30%。其余菌种和菌株表现出中等程度的消耗。在用血链球菌903进行的研究中，正常或加热（90℃，30分钟）的细菌均可消耗溶菌酶，且溶菌酶可从该菌中回收。此外，在适当条件下，0℃和37℃时细胞对溶菌酶的消耗非常相似。基于这些观察结果，我们得出结论，消耗是由于该菌对溶菌酶的吸附所致。对于血链球菌903，溶菌酶吸附取决于细菌浓度、孵育时间和培养基的离子强度。然而，吸附程度与3.9至8.3的pH值无关。当使用低浓度的血链球菌903时，每毫升添加20μg溶菌酶时，溶菌酶吸附达到饱和（每10⁷个细胞吸附4μg溶菌酶）。其他几种口腔微生物（黏性放线菌WVU 626和WVU 627、血链球菌73x11、变形链球菌BHT以及唾液链球菌NG）对唾液溶菌酶的吸附在对离子强度的敏感性方面与血链球菌903相似。血链球菌903从缓冲溶液或唾液上清液中吸附溶菌酶时，0℃比37℃对离子强度更敏感。基于在唾液与缓冲液中进行的实验结果，我们得出结论，唾液除了提供离子强度来源外，对血链球菌903吸附溶菌酶的程度没有主要影响。将血链球菌903吸附溶菌酶时pH和离子强度的影响与关于溶菌酶对全细胞的裂解以及细胞壁、肽聚糖和（GlcNAc）₄的水解的文献报道进行比较，结果表明血链球菌903的吸附比溶菌酶催化更依赖于静电相互作用。文中讨论了阴离子细菌表面成分介导溶菌酶吸附并缓和溶菌酶对微生物潜在影响的可能性。
