Smalley J W, Birss A J, McKee A S, Marsh P D
Department of Clinical Dental Sciences, University of Liverpool, U.K.
FEMS Microbiol Lett. 1991 Dec 15;69(1):63-7. doi: 10.1016/0378-1097(91)90647-s.
Porphyromonas gingivalis strain W50 was grown in a chemostat either under haemin limitation or haemin excess at pH 7.3. Cells and the extracellular vesicle (ECV) and extracellular protein (EP) fractions were separated, quantified, and assayed for haemagglutination, protease activity and haemin binding. Under haemin-limitation, despite a reduction in cell yield, there was a 2.5-fold increase in the gravimetric yield of extracellular vesicles. Cells and vesicles from haemin-limited cultures, haemagglutinated sheep red blood cells to higher titres than their haemin-excess counterparts. Growth in haemin-excess conditions resulted in increased haemin-binding capacities of ECV, cells and EDTA-extracted outer membrane. Cells grown under haemin-excess showed a 2-fold elevation in specific activity towards the substrate N-alpha-benzoyl-L-arginine-p-nitroanilide (L-BAPNA) compared to haemin-limited cells. The specific activities against L-BAPNA for haemin-limited ECV were 3-fold greater than their haemin-excess counterparts. These vesicle activities represented 25% and 3% of the total culture protease activity under haemin limited and haemin excess conditions respectively.
牙龈卟啉单胞菌菌株W50在恒化器中于pH 7.3的条件下，分别在血红素限制或血红素过量的情况下培养。分离、定量细胞以及细胞外囊泡（ECV）和细胞外蛋白（EP）组分，并检测其血凝、蛋白酶活性和血红素结合能力。在血红素限制条件下，尽管细胞产量降低，但细胞外囊泡的重量产量增加了2.5倍。来自血红素限制培养物的细胞和囊泡比血红素过量培养物的对应物能使绵羊红细胞凝集到更高的滴度。在血红素过量条件下生长导致ECV、细胞和经EDTA提取的外膜的血红素结合能力增加。与血红素限制的细胞相比，在血红素过量条件下生长的细胞对底物N-α-苯甲酰-L-精氨酸对硝基苯胺（L-BAPNA）的比活性提高了2倍。血红素限制的ECV对L-BAPNA的比活性比血红素过量的对应物高3倍。在血红素限制和血红素过量条件下，这些囊泡活性分别占总培养物蛋白酶活性的25%和3%。
