"Acidic pH-sensitive mutants": acid resistance in acetic acid bacteria

1)采用亚硝基还原和复制法，从酿酒葡萄糖杆菌IFO 3267菌株中分离到15株酸性pH敏感突变株。分离的菌株表现出溶解&lt；CaCO3&gt；的性质，不将乳酸和乙酸盐氧化成二氧化碳和水，并存在辅酶Q-10。菌株的无细胞提取液具有膜结合型葡萄糖脱氢酶、5-酮果糖还原酶、膜结合型甘露醇脱氢酶等酶活性。然而，在中性pH及其附近观察到较好的生长。在分离到的突变株中，PSM-51、PSM-、PSM-104、PSM-110、PSM-120和PSM-121等6株菌株对酸性和碱性PHS特别敏感。它们在pH值为6.0时生长最快。但在中性pH的两侧，即pH 5.0和pH 7.0，它们的生长逐渐减弱。3)成员…对所有突变菌株进行了更多的脂肪成分分析。突变株PSM-51、PSM-120和PSM-121的磷脂组成与出发菌株不同。首先，PSM-51的磷脂酰乙醇胺含量由原来的2倍增加到3倍，而磷脂酰胆碱的含量从25%降低到30%。其次，另两株突变菌株PSM-120和PSM-121的磷脂含量为出发菌株的60%。4)利用完整细胞和含有甲硫氨酸的PSM-51无细胞提取物分析了磷脂酰乙醇胺生物合成磷脂酰胆碱的途径。5)用放射性弱有机酸5，5-二甲基[2-(14)C&gt；]恶唑烷-2，4-二酮跨细胞膜测定突变株和亲本的胞内和胞外PHS。在亲本菌株中，胞外pH的变化不影响胞内pH，即从pH 3.0到pH 7.0：胞内pH几乎一直保持在pH 6.0-6.5的范围内。另一方面，在pH为4.0的条件下，所有突变菌株的胞内pH均降至pH 5.9以下。在胞外pH为3.0的条件下，突变菌株的胞内pH值不能被测定。出发菌株的胞内pH保持在6.03左右。较少

1) Fifteen strains of acidic pH-sensitive mutants were isolated from Gluconobacter cerinus IFO 3267 by treatment of nitrosoguanidine, followed by the conventional replica method. The isolated strains showed the properties of the dissolution of <CaCO_3> , the absence of oxidizing lactate and acetate to carbon dioxide and water and the presence of ubiquinone-10. The cell-free extracts of the strains had the respective enzyme activities of membrane-bound glucose dehydrogenase, 5-ketofructose reductase, mambrane-bound mannitol dehydrogenase and so on.2) The growth of all the mutant strains was negative at pH 4.0. However, the better growth was observed at and near the neutral pH. Of the isolated mutant strains, the six strains of PSM-51, PSM-64, PSM-104, PSM-110, PSM-120 and PSM-121 were especially sensitive to the acid and alkaline pHs. They showed maximal growth at pH 6.0. However, in the both sides of the neutral.pH, i.e., pH 5.0 and pH 7.0, their growth gradually decreased.3) The membr … More ane lipid composition of all the mutant strains were analyzed. Three mutant strains, PSM-51, PSM-120 and PSM-121 were different in phospholipid composition compared with the parent strain. Firstly, PSM-51 was increased in the content of phosphatidylethanolamine from two to three times and decreased in that of phosphatidylcholine from 25 to 30%. Secondly, other two mutant strains, PSM-120 and PSM-121 had 60% phospholipid content compared with the parent strain.4) The biosynthetic pathway of phosphatidylcholine from phosphatidylethanolamine was analyzed by using the intact cells and the cell-free extract of PSM-51 with [methyl- <^(14)C> ]methionine. The activities of the mutant strain was 60% in the intact cells and the same in the cell-free extract compared with the parent strain.5) The intracellular and extracellular pHs of the mutant and the parent strains were measured across the cell membrane with a radioactive weak organic acid, 5,5-dimethyl[2- <^(14)C> ]oxazolidine-2,4-dione. In the parent strain, the intracellular pH was not affected by the alteration of the extracellular pH, i.e., from pH 3.0 to pH 7.0: the intracellular pH was almost constantly retained in the pH range of 6.0-6.5. On the other hand, the intracellular pH of all the mutant strains decreased below pH 5.9 when incubated at pH 4.0. At the extracellular pH 3.0, the intracellular pHs of the mutant strains were not able to be measured. The intracellular pH of the parent strain was retained at pH 6.03. Less