Ross R A, Onderdonk A B
Departments of Medicine, Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Infect Immun. 2000 Sep;68(9):5205-9. doi: 10.1128/IAI.68.9.5205-5209.2000.
The effect of O(2) and CO(2) on expression of toxic shock syndrome toxin 1 (TSST-1) by Staphylococcus aureus was investigated under controlled growth conditions with continuous-culture techniques. To stimulate TSST-1 production, air and anaerobic gas were premixed before delivery to the culture vessel. At a growth rate-or mass doubling time (t(d))-of 3 h, production of specific TSST-1 (expressed as micrograms per milligram of cell dry weight) was 5. 9-fold greater at an O(2) concentration of 4% than under anaerobic conditions. Increasing the O(2) concentration to 11% did not result in a significant increase (P> 0.05) in the rate of toxin production over that during growth in 4% O(2) but did result in a significant increase (4.9-fold; P<0.001) in the rate of toxin production over that during anaerobic growth. At a t(d) of 9 h, addition of 3.5% O(2) resulted in a 7.6-fold increase in specific TSST-1 production. When room air was sparged through a culture growing at a t(d) of 9 h, TSST-1 production increased significantly (by 3.4-fold) over that during anaerobic growth. When a growth environment of 4% O(2)-remainder N(2) was studied, no increase in TSST-1 production was observed; this was also the case with 8% O(2) at gas-flow rates of 0.1, 0.2, and 0.4 liters/min. In all experiments, production of biomass (expressed as milligrams of cell dry weight per milliliter) increased, indicating that O(2) was metabolized by S. aureus. Addition of CO(2) to the gas mix (4% O(2), 10% CO(2), 86% N(2)) resulted in a 5.1- to 6.8-fold increase in TSST-1 production over that during anaerobic growth and a 3.6-fold increase over that during growth in an environment of 4% O(2)-remainder N(2). The agr mutant strain tested produced 6.1-fold more specific TSST-1 in a growth environment of 4% O(2)-10% CO(2)-86% N(2) than during anaerobic growth. These data suggest that in this system, O(2) alone does not trigger production of TSST-1; rather, both CO(2) and O(2) are required.
在可控生长条件下，采用连续培养技术研究了氧气（O₂）和二氧化碳（CO₂）对金黄色葡萄球菌产生毒性休克综合征毒素1（TSST-1）的影响。为刺激TSST-1的产生，在将空气和厌氧气体输送到培养容器之前先进行预混合。在生长速率或质量倍增时间（t(d)）为3小时时，氧气浓度为4%时特定TSST-1的产生量（以每毫克细胞干重微克数表示）比厌氧条件下高5.9倍。将氧气浓度提高到11%，毒素产生速率相比在4%氧气中生长时没有显著增加（P>0.05），但相比厌氧生长时毒素产生速率显著增加（4.9倍；P<0.001）。在t(d)为9小时时，添加3.5%的氧气导致特定TSST-1产生量增加7.6倍。当向以t(d)为9小时生长的培养物中鼓入室内空气时，TSST-1的产生量相比厌氧生长时显著增加（3.4倍）。当研究4%氧气-其余为氮气的生长环境时，未观察到TSST-1产生量增加；在气体流速为0.1、0.2和0.4升/分钟的情况下，8%氧气时也是如此。在所有实验中，生物量的产生量（以每毫升细胞干重毫克数表示）增加，表明金黄色葡萄球菌可代谢氧气。向气体混合物（4%氧气、10%二氧化碳、86%氮气）中添加二氧化碳，导致TSST-1产生量相比厌氧生长时增加5.1至6.8倍，相比在4%氧气-其余为氮气的环境中生长时增加3.6倍。所测试的agr突变株在4%氧气-10%二氧化碳-86%氮气的生长环境中产生的特定TSST-1比厌氧生长时多6.1倍。这些数据表明，在该系统中，仅氧气不会触发TSST-1的产生；相反，二氧化碳和氧气都是必需的。
