Marsh P D, McDermid A S, McKee A S, Baskerville A
Pathology Division, PHLS Centre for Applied Microbiology and Research, Porton Down, Salisbury, UK.
Microbiology (Reading). 1994 Apr;140 ( Pt 4):861-5. doi: 10.1099/00221287-140-4-861.
Porphyromonas gingivalis strain W50 was grown under haemin-limitation and haemin-excess conditions in a chemostat at pH 7.5. The maximum specific growth rate (mumax) was determined at both haemin concentrations (mumax = 0.236 +/- 0.052 and 0.271 +/- 0.039 h-1, respectively). This enabled dilution rates to be adjusted so that the virulence and enzyme activity of haemin-limited and haemin-replete cells could be compared at identical relative growth rates (murel) of 0.25, 0.50 and 0.75 of their respective mumax. The data showed that the fastest growing cells were significantly more virulent than those grown more slowly, irrespective of haemin concentration. However, at each growth rate tested, cells grown under haemin-excess conditions were always more virulent than haemin-limited cells. Trypsin-like enzyme activity of whole cultures was also greater at each growth rate under haemin-excess conditions while, conversely, collagenolytic activity was generally higher in haemin-limited cultures. Thus, although growth rate had an effect on the virulence and enzyme activity of P. gingivalis, the availability of haemin for growth was the most significant factor.
牙龈卟啉单胞菌W50菌株在恒化器中于pH 7.5的条件下，分别在血红素限制和血红素过量条件下培养。测定了两种血红素浓度下的最大比生长速率（μm ax）（分别为μm ax = 0.236 ± 0.052和0.271 ± 0.039 h-1）。这使得稀释率得以调整，从而能够在血红素限制和血红素充足的细胞各自μm ax的0.25、0.50和0.75的相同相对生长速率（murel）下比较其毒力和酶活性。数据表明，无论血红素浓度如何，生长最快的细胞比生长较慢的细胞毒力显著更强。然而，在每个测试的生长速率下，在血红素过量条件下生长的细胞总是比血红素限制的细胞毒力更强。在血红素过量条件下，全培养物的类胰蛋白酶活性在每个生长速率下也更高，相反，在血红素限制的培养物中胶原酶活性通常更高。因此,虽然生长速率对牙龈卟啉单胞菌的毒力和酶活性有影响，但血红素对生长的可利用性是最重要的因素。
