STUDIES ON THE METABOLISM OF AUTOTROPHIC BACTERIA : II. THE NATURE OF THE CHEMOSYNTHETIC REACTION

In a study of chemosynthesis (the fixation of CO₂ by autotrophic bacteria in the dark) in Thiobacillus thiooxidans, the data obtained support the following conclusions: 1. CO₂ can be fixed by "resting cells" of Thiobacillus thiooxidans; the fixation is not "growth bound." 2. The physiological condition of the cell is of considerable importance in determining CO₂ fixation. 3. CO₂ fixation can occur in the absence of oxidizable sulfur in "young" cells. The extent of this fixation appears to be dependent upon the pCO₂. 4. CO₂ fixation can also occur under anaerobic conditions and the presence of sulfur does not influence such fixation. 5. However, in the CO₂ fixation by cells in the absence of sulfur, only a limited amount of CO₂ can be fixed. This amount is approximately 40 µl. CO₂ per 100 micrograms bacterial nitrogen. After a culture has utilized this amount of CO₂ it no longer has the ability to fix CO₂ but releases it during its respiration. 6. Relatively short periods of sulfur oxidation can restore the ability of cells to fix CO₂ under conditions where sulfur oxidation is prevented. 7. It is possible to oxidize sulfur in the absence of CO₂ and to store the energy thus formed within the cell. It is then possible to use this energy at a later time for the fixation of CO₂ in the entire absence of sulfur oxidation. 8. Cultures of Thiobacillus thiooxidans respiring on sulfur utilize CO₂ in a reaction which proceeds to a zero concentration of CO₂ in the atmosphere. 9. CO₂ may act as an oxidizing agent for sulfur. 10. Hydrogen is not utilized by the organism. 11. It is possible to selectively inhibit sulfur oxidation and CO₂ fixation.     

STUDIES ON THE METABOLISM OF AUTOTROPHIC BACTERIA : I. THE RESPIRATION OF THIOBACILLUS THIOOXIDANS ON SULFUR

The data of this paper indicate that: 1. The "energy of activation" (µ) of sulfur oxidation by the autotrophic bacterium, Thiobacillus thiooxidans, is similar to that of other respirations. 2. The pH of the menstruum does not influence the respiration on sulfur between the limits of pH 2 to 4.8 once contact between the bacterial cell and the sulfur particle has been established but it does influence the rate at which such contact occurs. 3. The pO₂ has little effect upon the respiration of this organism. 4. Most organic materials have no detectable effect upon the respiration of Thiobacillus thiooxidans, but the organic acids of terminal respiration seem to stimulate the respiration in the absence of oxidizable sulfur and certain of them inhibit sulfur oxidation. 5. In so far as inhibitor studies on intact cells are trustworthy, sulfur oxidation goes through iron-containing systems similar to cytochrome. It is possible that the oxygen contained in the sulfuric acid formed during sulfur oxidation is derived from the oxygen of the water.     

THE PRESENCE OF AN ENDOGENOUS RESPIRATION IN THE AUTOTROPHIC BACTERIA

It is shown that there exists in the autotrophic bacterium Thiobacillus thiooxidans a measurable oxygen uptake in the absence of the specific nutrient (sulfur). This respiration is shown to be due to the utilization of organic materials which must have been previously synthesized by the chemosynthetic process, providing evidence that autotrophic bacteria contain a dissimilatory process which involves the breakdown of organic materials and furnishes energy for the maintenance of the cell during periods in which the specific nutrient is absent. This is entirely in accord with the work of Bömeke (1939), who provided similar types of proof for Nitrosomonas and Nitrobacter. One may conclude, therefore, that autotrophic bacteria possess an endogenous respiration which involves the utilization of previously synthesized organic materials.     

冷驯化对中缅树鼩能量代谢的影响

在5 ±1 ℃条件下对中缅树鼠句进行冷驯化处理, 测定其能量代谢。冷驯化28 d 后, 体重比对照组显著增加7.33 %; 整体能值达到30.47 ±0.46 kJ / g (N = 8) , 比对照组增加4.98 %; 摄入能比对照组增加36.17 %; 同化能比对照组增加66.2 %; 生长能达到6.98 ±0.53 kJ / 100 g (N = 7) 体重·天, 是对照组的4.85 倍; 维持能比对照组增加64.0 % , 达到352.96 ±28.34 kJ / 100 g 体重·天(N = 7) 。以上结果表明中缅树鼠句在冷胁迫影响下, 以增加能量摄入、能量储存和维持能和降低排泄能量的生理机制来维持能量代谢平衡, 以此对策来提高低温环境适应能力。
     

梅花鹿生茸期能量代谢的初步研究

通过呼吸测热试验,结合不同能量进食水平和不同蛋白质水平条件下的消化、代谢试验,对成年梅花鹿生茸期的能量代谢规律进行了研究。结果表明：（１）梅花鹿的产热量（ＨＰ）和体能沉积量（ＲＥ）均随总能食入量（ＧＥＩ）的增加而增加;代谢能转化为体蛋白能和体脂肪能沉积的效率（Ｋｇｐ和Ｋｇｆ）分别为０．５９和０．６１;产热量（ＨＰ）与总能食入量（ＧＥＩ）的回归方程为：ＨＰ（ｋＪ／Ｗ０．７５ｄ）＝２６５．１２＋０．３３２ＧＥＩ（ｋＪ／Ｗ０．７５ｄ）。（２）产热量占总能食入量的百分比（ＨＰ／ＧＥＩ）,无论是在生茸期前期还是在生茸期后期,低蛋白组（ＣＰ为２２．０％）均明显高于高蛋白组（ＣＰ为２９．０％）（Ｐ＜０．０５）,在同一蛋白水平下生茸期前期与后期各组之间无显著差异（Ｐ＞０．０５）;体能沉积量占总能食入量的百分比（ＲＥ／ＧＥＩ）各组之间差异均不显著（Ｐ＞０．０５）;无论在生茸期前期还是在生茸期后期,体蛋白能沉积量占体能沉积量的百分比（ＲＰＥ／ＲＥ）,高蛋白组均高于低蛋白组（Ｐ＜０．０５）,而体脂肪能沉积量占体能沉积量的百分比（ＲＦＥ／ＲＥ）则与其相反（Ｐ＜０．０５）。     

冷驯化对中缅树能量代谢的影响

在 5± 1℃条件下对中缅树鼠句进行冷驯化处理 ,测定其能量代谢。冷驯化 2 8d后 ,体重比对照组显著增加 7 3 3 % ;整体能值达到 3 0 47± 0 46kJ/g (N =8) ,比对照组增加4 98% ;摄入能比对照组增加 3 6 1 7% ;同化能比对照组增加 6 6 2 % ;生长能达到 6 98±0 5 3kJ/1 0 0g (N =7)体重·天 ,是对照组的 4 85倍 ;维持能比对照组增加 6 4 0 % ,达到3 5 2 96± 2 8 3 4kJ/1 0 0g体重·天 (N =7)。以上结果表明中缅树鼠句在冷胁迫影响下 ,以增加能量摄入、能量储存和维持能和降低排泄能量的生理机制来维持能量代谢平衡 ,以此对策来提高低温环境适应能力     

我国家居蜚蠊细菌的研究

从我国不同地区的147头家居蜚蠊中分离获得562株细菌分属于13个属,其优势菌群属于埃希氏菌属、芽抱杆菌属、短杆菌属共422株菌,占总菌数的75．09％;其次为沙雷氏菌属、假单胞菌属共85株,占总数的15．12％;其他8个属仅43株菌,占总数的9．25％。比较了德国小蠊、美洲大蠊和黑胸大蠊及它们的体表、体腔、中肠和粪便所携带的细菌类群和数量,其结果有很大差异。该文讨论了蜚蠊细菌与人类疾病之间的关系。     

STUDIES ON LUMINOUS BACTERIA : II. THE INFLUENCE OF TEMPERATURE ON THE INTENSITY OF THE LIGHT OF LUMINOUS BACTERIA.

1. A method has been described whereby the intensity of the light of luminous bacteria may be measured in a quantitative manner. 2. It is pointed out that the temperature coefficients for light intensity do not follow the van''t Hoff rule, but are higher and vary with each 10° temperature interval. 3. From a comparison with other data it is found that the process is not a simple one, but that the observed curve is the resultant of several reactions which proceed simultaneously. 4. The discrepancies in the temperature coefficients in the neighborhood of the "optimum temperature" may be due to a process of coagulation of the colloidal particles of the enzyme. This coagulation will tend to cause a deviation of the curve away from that normal for chemical reactions.     

STUDIES ON THE METABOLISM OF UREA AND OTHER NITROGENOUS COMPOUNDS IN CHLORELLA ELLIPSOIDEA: III ASSIMILATION OF UREA

Assimilation of urea by Chlorella ellipsoidea was investigatedby using ¹⁴C-urea. It was revealed that urea carbon metabolizedby the N-starved cell was almost quantitatively recovered incarbon dioxide under dark-aerobic conditions. The rate of ureaconsumption was considerably influenced by the N-content ofalgal cells, practically no metabolism of urea being observedwith the cells containing more than 7 per cent N on a dry weightbasis. Similar results were also obtained when urea was replacedwith ammonia as nitrogen source. Based on the results obtained,a tentative scheme for the assimilation process of urea in Chlorellawas proposed. (Received February 7, 1960; )     

STUDIES ON THE METABOLISM OF A SULFUR-OXIDIZING BACTERIUM III. POSTOXIDATIVE FIXATION OF CARBON DIOXIDE

1. The cells of Thiobacillus thiooxidans, which had been in contactwith sulfur or sulfide in air (or CO₂-free air), could fix addedCOa very rapidly after replacing air with nitrogen. This fixationis designated as the postoxidative fixation.
2. "Preoxidation"of the sulfur compounds is mandatory for theoccurrence of thepostoxidative fixation.
3. The cells which had preliminarilyoxidized sulfide could notshow the CO₂-fixation, when theywere placed under an anaerobiccondition in the absence of thesulfur compound.
4. These results indicate that sulfur compoundsmay have an importantrole as the electron donor for the reductionof CO₂, besidestheir role as the substrate of respiration tosecure energyfor the fixation of CO₂

(Received March 6, 1962; )     

我国冰核活性细菌的优势种类调查与研究

１９８６￣１９９４年,从国内１７个省、市、自治区的６８种植物上分离到了２５０株冰核活性细菌,经鉴定分别属于３个属的１７个种或致病变种。其中出现最多的是菠萝欧文氏菌,共１３３株,占总数的５３．２％,其次是丁香假单胞菌群,共７０株,占２８％,其它种类的冰核活性细菌共４７株,仅占１８．８％。因此,我国冰核活性细菌的优势菌种是Ｅ．ａｎａｎａｓ,其次是Ｐ．ｓｙｒｉｎｇａｅ ｐｖｓ。在低纬度的南方地区中Ｅ．ａ     

焦磷酸在植物细胞能量代谢中的作用(综述)

ADVANCESINRESEARCHONTHEROLESOFPYROPHOSPHATEINCELLULARENERGYMETABOLISMOFPLANTSWangYixing(DepartmentofBiology,JinanUniversity,Guangzhou510632)LiMingqi(DepartmentofAgriculturalBiology,SouthChinaAgriculturalUniversity,Guangzhou510642)焦磷酸（PPi）是一种高能化合物,其水解的G为-33．4kJmol,即PPi水解释放的自由能与ATP相似（ATP水解为ADP和Pi的G为-31．3kJmol）。但是对于焦磷酸代谢的传统观点是：细胞内焦磷酸水平很低,代谢中的焦磷酸,主要是在大分子如蛋白质、淀粉等生…