伴放线放线杆菌产毒变异菌株白细胞毒素产量、生长速率与碳酸氢盐浓度的关系,Microbiology

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伴放线放线杆菌产毒变异菌株白细胞毒素产量、生长速率与碳酸氢盐浓度的关系
Microbiology ( IF 1.3 ) Pub Date : 1996-04-01 , DOI: 10.1099/00221287-142-4-963
Hiroyuki Ohta ₁ , Atsushi Miyagi ₁ , Keijiro Kato ₁ , Kazuhiro Fukui ₁

Affiliation

Actinobacillus actinomycetemcomitans，一种革兰氏阴性牙周病细菌，产生属于 RTX 家族的白细胞毒素。白细胞毒素的产生在该物种的不同菌株之间差异很大。在本文中，研究了生长速率和碳酸氢盐对在恒化器中生长期间毒素产生可变菌株 (301-b) 产生白细胞毒素的影响。当细菌在厌氧果糖限制的恒化培养物（pH 7.0 和 37 摄氏度）中以 0.04 至 0.20 h-1 的稀释率（D）在不存在和存在 10 mM 碳酸氢盐的情况下生长时，它会产生作为簇的白细胞毒素两种多肽（M(r) 113,000 和 120,000）并与细菌细胞表面上的核酸复合。通过将白细胞毒素产生的比值 [qLT，单位为微克 (mg 干重)-1 h-1] 与 D 作图来分析白细胞毒素产生与比生长速率之间的关系。这些图近似于线性关系 qLT = 2.7D -0.058 和 qLT = 9.3D-0.407 分别没有和有碳酸氢盐。这些关系表明，明显的白细胞毒素产生是生长速率依赖性产生和生长速率无关分解的结果。在同一发酵罐中从恒化器变为分批培养后，还跟踪细胞白细胞毒素水平。在分批培养中，白细胞毒素的产生立即停止，细胞毒素水平迅速下降，表明毒素分解。从 qLT 和 D 之间近似线性关系的斜率，在不存在和存在 10 mM 碳酸氢盐的情况下，理论最大白细胞毒素产量 (YLT) 估计分别为 2.7 和 9.3 微克（mg 干重）-1。在含有碳酸氢盐的培养物中增加的 YLT 值表明添加刺激了白细胞毒素合成的效率高达约三倍。碳酸氢盐浓度进一步增加到 20 到 40 mM 之间对总白细胞毒素的产生没有影响，但细胞外白细胞毒素的量随着碳酸氢盐浓度的增加而增加。

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The relationships between leukotoxin production, growth rate and the bicarbonate concentration in a toxin-production-variable strain of Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans, a Gram-negative periodontopathic bacterium, produces a leukotoxin belonging to the RTX family. The production of leukotoxin varies greatly among different strains of this species. In this paper the effects of growth rate and bicarbonate on the leukotoxin production by a toxin-production-variable strain (301-b) during growth in a chemostat were examined. When the bacterium was grown in anaerobic fructose-limited chemostat cultures (pH 7.0 and 37 degrees C) at dilution rates (D) ranging from 0.04 to 0.20 h-1 in the absence and presence of 10 mM bicarbonate, it produced leukotoxin as a cluster of two polypeptides (M(r) 113,000 and 120,000) and complexed with nucleic acids on the bacterial cell surface. The relationship between leukotoxin production and specific growth rate was analysed by plotting the specific rate of leukotoxin production [qLT, in microgram (mg dry wt)-1 h-1] against D. The plots were approximated to the linear relationships qLT = 2.7D-0.058 and qLT = 9.3D-0.407 without and with bicarbonate, respectively. These relationships suggest that the apparent leukotoxin production is a result of both growth-rate-dependent production and growth-rate-independent decomposition. The cellular leukotoxin level was also followed after the change from chemostat to batch culture in the same fermenter. In batch culture leukotoxin production stopped immediately and the cellular toxin level rapidly decreased, suggesting toxin decomposition. From the slopes of the approximated linear relationships between qLT and D, a theoretical maximum leukotoxin yield (YLT) was estimated as 2.7 and 9.3 micrograms (mg dry wt)-1 in the absence and presence of 10 mM bicarbonate, respectively. The increased YLT value in the cultures containing bicarbonate indicated that the addition stimulated the efficiency of leukotoxin synthesis up to about threefold. Further increases of bicarbonate concentration to between 20 and 40 mM had no effect on the total leukotoxin production, but the amount of extracellular leukotoxin increased with higher bicarbonate concentrations.

更新日期：1996-04-01

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