PRODUCTION OF HYDROGEN SULFIDE FROM SULFITE BY A COPPER-ADAPTED YEAST

Activity of hydrogen sulfide production from sulfite was studiedusing a copper-resistant yeast strain (R), its parent strain(P), and the culture of R in the medium without copper addition(R(0)). More hydrogen sulfide was produced under aerobic conditionthan under anaerobic condition. Sulfide producing activity wasin the order of R(0)>P>R under either condition. Stationaryphase cells produced more sulfide than logarithmic phase cellswhen cultured without copper, while the reverse was the casewith R, cultured in copper medium. Sulfide production was inhibitedby high concentrations of sulfite and by salicylaldoxime. Differencein the pathway from sulfite to sulfide was suggested betweenthe resistant strain (R and R(0)) and P in that the former wasmore sensitive to these inhibitors. ¹ Present address: Research Reactor Institute, Kyoto University,Kumatori-cho, Sennan-gun, Osaka     

ADAPTIVE PHOTOSYNTHESIS RESPONSES TO TEMPERATURE EXTREMES BY THE THERMOPHILIC CYANOPHYTE SYNECHOCOCCUS LIVIDUS1

The physiological and biochemical changes associated with and resulting in adaptation to both sub- and supra-optimal temperatures are presented for the thermophilic cyanophyte Synechococcus lividus Copeland. The optimum temperature for growth was 45 C. An increase in the optimum temperature of photosynthesis from 50 to 55 C was shown for cells grown at the supra-optimum temperature of 57 C; whereas, cells grown at the sub-optimal temperature of 35 C exhibited a decrease in the optimal temperature from 50 to 45 C for ¹⁴CO₂ uptake. These changes in optimal temperatures are interpreted as adaptive. Associated with the 5 C increase in optimal temperature for photosynthesis was an increase in chlorophyll a, plastoquinone A, and activity of ribulose-1,5-diphosphate carboxylase (RuDP carboxylase). However, the increase in the temperature optimum for 57 C grown cells was associated with a reduced O₂ yield correlated with a reduced ferricyanide photoreduction capacity. RuDP carboxylase activity decreased rapidly above 55 C. Therefore reduced rates above 55 C resulted from damage to ferricyanide reducing systems and reduced RuDP-carboxylase activity, whereas low photosynthesis rates at sub-optimal temperatures were probably due to rate limiting effect of low temperatures on RuDP carboxylase activity with no evidence of damage to ferricyanide photoreducing systems.     

ULTRASTRUCTURE OF THE THERMOPHILIC BLUE-GREEN ALGA,SYNECHOCOCCUS LIVIDUS COPELAND1

The ultrastructure of Synechococcus lividus Copeland, a thermophilic blue-green alga, was studied in thin sections. The cell envelope reveals striking similarities with that of some gram-negative bacteria. In contrast to bacteria and to many other species of blue-green algae, ribosomes are predominantly found in the central nuclear region and appear to be associated with the DNA fibrils. Thylakoids (photo-synthetic lamellae) are arranged as concentric shells, around the nuclear equivalent, lying nearly parallel to one another and to the plasma membrane. Both plasma and thylakoidal membranes, as described by other authors for different Cyanophyceae, are of the unit membrane dimension and morphology. Various types of intracellular inclusions are found: (1) Lipid inclusions, located in the cytoplasm are similar to the osmiophilic globules of higher plant chloroplasts. (2) Polyphosphate inclusions (or volutin) resembling those of other species are generally found at the cell poles but within the nuclear region. (3) Polyhedral inclusions also located in the nuclear region are clearly recognized to be different from the polyphosphate bodies, but their function remains unknown.     

THE OXIDATION OF HYDROGEN SULFIDE BY BEGGIATOA

Knowledge of the conditions in which Beggiatoa is capable of autotrophic nutrition is incomplete. It is not known whether sulfur-free trichomes from heterotrophic cultures are able to return to the utilization of H₂S-oxidation. Devices were developed which permitted the supply of pure cultures of Beggiatoa, previously cultivated heterotrophically, with H₂S, O₂, and CO₂. Development in media devoid of organic nutrients was achieved, and subculturing under autotrophic conditions could be repeated indefinitely. The strains used behaved differently with respect to their tendency to grow autotrophically. The ability to dispense with organic substrates corresponds to the place in the groups to which they had previously been assigned. All the strains multiplied better when, under otherwise equal conditions, the inorganic medium was supplemented with acetate, very low concentrations of which were effective. This result may, however, be due to the selection of varieties by the isolation procedure. The mixotrophic tendency of our strains may not be a general feature of the genus. There are indications that the wider forms of Beggiatoa tend more toward autotrophic growth than the narrower ones.     

THE PRODUCTION OF HYDROGEN PEROXIDE BY BLUE-GREEN ALGAE: A SURVEY1

A survey of 38 axenic isolates of blue-green algae indicated that over half the isolates produced hydrogen peroxide under defined growth conditions. Three kinetic profiles for the formation of hydrogen peroxide, were observed; these are described. The possible site or sites of hydrogen peroxide formation remain unknown.     

光合细菌产氢研究进展

光合细菌能利用有机废水(废弃物)转化太阳能产生氢能,故应作为环保产业新能源开发的一个重要研究方向。       

THE EFFECTS OF SOME ECOLOGICAL FACTORS ON CELL SIZE OF THE HOT SPRING ALGA SYNECHOCOCCUS LIVIDUS (CYANOPHYTA)1

Algae were sampled along temperature gradients of 30 thermal springs in Colorado, Idaho, Montana and Wyoming. From a maximum temperature of 74.5 C downstream, to ca. 62 C, the diversity of the algae was limited to the various forms of Synechococcus lividus Copeland; from ca. 62 to 40–45 C it coexisted with other algae. When S. lividus was in direct sunlight the mean length was greatest at the highest temperatures of its existence, becoming shorter as the water cooled; the mean reduction in length was 0.132 μm for each 1 C reduction in temperature. The cells in a shaded stream did not exhibit the reduction in size with reduced temperature, but remained about the same length from 73 C downstream to 45 C. The longer cells from the highest temperatures of their existence in any stream could not become established in the cooler water downstream, so the range of cell lengths (diversity) became less as the water cooled. Unknown dissolved substance(s) depressed the upper temperature limit in two streams and had a reverse effect on the expected length–temperature relationship; the shortest cells were at the higher temperatures. Generally, total dissolved substances had a positive effect on the length; the longest cells were in the water with the highest total dissolved solids (TDS) at the upper temperature limits of 70–74.5 C. In the temperature range of 55–60 C the higher TDS were not as effective in developing longer cells.     

PHOSPHATE UPTAKE BY SYNECHOCOCCUS LEOPOLIENSIS (CYANOPHYCEAE): ENHANCEMENT BY CALCIUM ION1

The influence of metallic, cations (added at 10 μM-1 mM) on the uptake of orthophosphate from 0.2–10 μM solution by Synechococcus leopoliensis (Racib.) Komarek was investigated. All cations tested except Mg²⁺ and Zn²⁺ stimulated phosphate uptake. The most pronounced stimulation of phosphate uptake was caused by Ca²⁺·Ca²⁺ markedly decreased the half-saturation concentration for orthophosphate uptake, apparently by acting upon the metabolic processes of phosphate transport into the cell. Phosphate did not influence Ca²⁺ fluxes across the cell-surface.     

PHOTOSYNTHESIS AND PRODUCTION OF HYDROGEN PEROXIDE BY SYMBIODINIUM (PYRRHOPHYTA) PHYLOTYPES WITH DIFFERENT THERMAL TOLERANCES1

Occurrences whereby cnidaria lose their symbiotic dinoflagellate microalgae (Symbiodinium spp.) are increasing in frequency and intensity. These so‐called bleaching events are most often related to an increase in water temperature, which is thought to limit certain Symbiodinium phylotypes from effectively dissipating absorbed excitation energy that is otherwise used for photochemistry. Here, we examined photosynthetic characteristics and hydrogen peroxide (H₂O₂) production, a possible signal involved in bleaching, from two Symbiodinium types (a thermally “tolerant” A1 and “sensitive” B1) representative of cnidaria–Symbiodinium symbioses of reef‐building Caribbean corals. Under steady‐state growth at 26°C, a higher efficiency of PSII photochemistry, rate of electron turnover, and rate of O₂ production were observed for type A1 than for B1. The two types responded very differently to a period of elevated temperature (32°C): type A1 increased light‐driven O₂ consumption but not the amount of H₂O₂ produced; in contrast, type B1 increased the amount of H₂O₂ produced without an increase in light‐driven O₂ consumption. Therefore, our results are consistent with previous suggestions that the thermal tolerance of Symbiodinium is related to adaptive constraints associated with photosynthesis and that sensitive phylotypes are more prone to H₂O₂ production. Understanding these adaptive differences in the genus Symbiodinium will be crucial if we are to interpret the response of symbiotic associations, including reef‐building corals, to environmental change.     

THE KINETICS OF PENETRATION : XII. HYDROGEN SULFIDE

The rate of entrance of H₂S into cells of Valonia macrophysa has been studied and it has been shown that at any given time up to 5 minutes the rate of entrance of total sulfide (H₂S + S^-) into the sap is proportional to the concentration of molecular H₂S in the external solution. This is in marked contrast with the entrance of ammonia, where Osterhout has shown that the rate of entrance of total ammonia (NH₃ + NR₄ ⁺) does not increase in a linear way with the increase in the external concentration of NH₃, but falls off. The strong base guanidine also acts thus. It has been shown that the rate of entrance of H₂S is best explained by assuming that it enters by diffusion of molecular H₂S through the non-aqueous protoplasmic surface. It has been pointed out that the simple diffusion requires that the rate of entrance might be expected to be monomolecular. Possible causes of the failure of H₂S to follow this relationship have been discussed.     

尼日利亚菌素高产菌株的选育

通过对致死率和正负突变率的测定,确定了紫外线、亚硝酸、紫外线加吖啶橙3种诱变方式对吸水链霉菌NND-52的29号菌株进行诱变处理的合适剂量,并采用复合诱变得到了一株脱葡萄糖阻遏的高产菌株A19,其尼日利亚菌素的摇瓶产量比出发菌株提高了128％。传代结果表明,在传代的同时结合自然分离,可以保持稳定的产抗特性。     

血链球菌产生过氧化氢机理研究

作者在国内首次建立两种确定细菌产生过氧化氦的方法,可以定性和定量分析。本文探讨了血链球菌产生过氧化氢的条件,研究其在牙周微生态环境中的作用。     

DIMETHYLSULFONIOPROPIONATE PRODUCTION BY PSYCHROPHILIC DIATOM ISOLATES1

Dimethylsulfoniopropionate (DMSP) production by psychrophilic diatom strains, Chaetoceros sp., Navicula sp., and Nitzschia sp., were experimentally analyzed. All strains showed rapid growth (0.3–0.5 d^?1) under cold culture conditions (1.7°C). DMSP concentrations (both as particulate, DMSP_p, and dissolved, DMSP_d) were negligible in cultures of Chaetoceros sp., whereas those for Navicula sp. and Nitzschia sp. increased toward the end of the 56‐day experiments. The ratio of DMSP_p:chl a of the latter two species was approximately 5 in the early exponential growth phase and decreased slightly toward the early stationary phase. During the stationary phase, when chl a and fluorescence remained constant, the ratios in both species increased linearly by up to approximately 6.5 times the value at the start of the stationary phase. This growth‐related DMSP production by diatoms may result in the low concentrations of DMSP_p observed in the early stage of diatom blooms under natural conditions.     

固定化桔青霉产生核酸酶P_1的研究

利用吸附固定在多孔聚酯载体上的桔青霉(Penicillium citrinum)菌丝细胞,在摇瓶中以分批发酵方式合成核酸酶P_1.试验结果表明:在固定化细胞产酶的条件下,培养液中葡萄糖和蛋白胨的最适浓度分别为10g/L和1g/L,摇瓶转速以180~200r/min为宜.固定化细胞经过48h的产酶周期,培养液中的核酸酶P_1活力可高达513.3U/ml,其产酶效率是游离菌丝的3.6倍,而葡萄糖和蛋白胨的用量仅为游离菌丝产酶的五分之一.在重复分批发酵试验中,固定化菌丝细胞形状稳定,连续28批(共56d)的产酶结果基本一致,每批的平均酶活力为507.4U/ml,在经济上和工艺上均显示了明显的优越性.     

血链球菌拮抗可疑牙周病原菌机理探讨Ⅲ过氧化氢产生及影响因素

本研究采用过氧化物酶法,定性和定量分析不同条件下血链球菌产生的过氧化氢,结果显示,过氧化酶法则定过氧化氢的最小浓度为３ｐｐｍ,过氧化氢产生的量随血链球菌生长速度提高而增加,在对数生长期产量最多,２４小时后速度减慢。血链球菌产生过氧化氢的最高值为０．０２％。在厌氧条件下,血链球菌不产生或很少产生过氧化氢。     

THE EFFECT OF HYDROGEN ION CONCENTRATION ON THE PRODUCTION OF CARBON DIOXIDE BY BACILLUS BUTYRICUS AND BACILLUS SUBTILIS

1. The maximum rate of CO₂ production of Bacillus butyricus was found to be at a pH value of 7; of Bacillus subtilis at pH 6.8. If the pH value be raised or lowered there is a progressive decrease in the rate of production of CO₂. 2. Spontaneous recovery follows the addition of alkali to either organism, while addition of acid is followed by recovery only upon addition of an equivalent amount of alkali, and is not complete except when the amount of acid is very small.