混合培养对光合细菌生长量的影响

采用光合细菌不同菌株,光合细菌株与异养细胞株间混合培养,比较它们与单株培养物生长量的差异。试验结果表明,不同组合的混合培养物春生长量均不同程度高于单株培养物。光合细菌株间混合培养物生长量约高于对照０．３６－１７．４％;多数增长１１％以上。光合细菌株与异养细胞     

COMPARATIVE STUDIES OF PHOTOSYNTHETIC PROCESSES IN ORDINARY AND FULLY DEUTERATED ALGAE

The light-saturated growth rate of fully deuterated algae hasbeen found less than that of ordinary algae by a factor of threeto four. However, as compared to the net rate of photosynthesis,the Hill reaction rate indicates an unimpaired light reactionsystem. Analysis of cell extracts for amino acid content and¹⁴C-uptake studies indicate a decreased utilization of the productsof photosynthesis by deuterated algae, probably because of agenerally lowered protein metabolism. We conclude that in algaeD₂O does not have a pronounced effect on the light reactionin photosynthesis. ¹ Based on work performed under the auspices of the U. S. AtomicEnergy Commission. ² Resident Research Associate, 1962–64. ³Present address: University of Illinois, Department of Pharmacy,Chicago, Illinois.     

GROWTH AND EXCRETION IN PLANKTONIC ALGAE AND BACTERIA1

In short-term experiments using cultures of Chlorella pyrenoidosa, Anabaena flos-aquae, Asterionella formosa, and Navicula pelliculosa, both the proportion of photosynthetic products released from cells and the composition of these products altered, with age. In the first 3 species, percentage extracellular release values increased with increasing growth rates but the reverse trend was shown by Navicula. Fractionation of filtrates using Sephadex indicated that, in general, larger molecular weight compounds became predominant as cultures aged. Also a time-dependent shift in a similar direction occurred in cultures of all ages. In several lakes a predominance of large molecular weight compounds was apparent in filtrates even from short-term experiments. Filtrates of mixed cultures of planktonic bacteria growing on ¹⁴C glycolate were found to contain, large molecular weight organic compounds. It was demonstrated that in nonaxenic cultures of algae and in lake water, bacteria utilize low molecular weight extracellular metabolites of algal origin and larger molecular weight compounds are formed.     

SOME FACTORS IN THE COMPETITION OR ANTAGONISM AMONG BACTERIA, ALGAE, AND AQUATIC WEEDS

Field observations of changes in the populations of aquatic weeds and phytoplankton have confirmed that aquatic weeds have antagonistic activity toward phytoplankton. Nutritional studies in the laboratory indicate that cultures of the aquatic weeds, Myriophyllum sp., Ceratophyllum sp., and duckweed (Lemma minor L.); liquid cultures of barley (Hordeum vulgare L., Dickson variety); and cultures of the filamentous green algae, Cladophora sp. and Pithophora oedogonium (Mont.) Withrock, will remain relatively free of epiphytes or competing phytoplankton if the cultures are nitrogen-limited. Field observations of Cladophora sp. have confirmed that the growth of epiphytes on the Cladophora is related to conditions of surplus available nitrogen compounds. It is proposed that this antagonistic activity may be due to a “nitrogen sink” effect in which the aquatic weeds or filamentous green algae prevent the growth of contaminating algae by competition for the limited nitrogen compounds available. However, the presence of bacteria-sized organisms which have selective toxicity to certain algae indicates that perhaps multiple factors exist. Discussed are the ecological implications of associations of certain algae with bacteria that have selective toxicities for other species of algae under certain environmental conditions such as nitrogen-limited growth.     

污水净化湿地模拟系统中细菌和藻类的生态分布研究

以湿地土壤－微生物模拟系统为基础,研究了细菌和藻类在不同处理单元中的生态分布和种类变化。随着系统中微生物的净化作用,污水中污染物浓度下降,污染负荷降低,细菌和藻类的种类和数量也发生相应的变化。系统中,藻类种类由耐污种类向喜清种类过渡,显示了藻类是良好的水质评价和监测的指示生物。细菌总量降低,第４单元中的细菌总量比第１单元要低２个数量级。Ｍａｒｇａｌｅｆ多样性指数逐渐升高,第１单元为０．３８,第２单元为０．６０,第３单元为０．６９,第４单元为０．８７。系统中的反硝化率在第２单元处最高,在第４单元处最低,垂直分布以２ｃｍ深度处最高。     

试论晚白垩世以来气候、地理等因素的变化对鼍类的进化及地理分布等影响

现存的鼍属只有两个种:即东亚的扬子鳄及北美的密河鳄。虽然这两个种的性质、纬度分布以及生态环境等都十分相似;但两者的水平分布的距离却几有地球的半圈。本文根据有关鼍类的进化、迁徙等的历史资料,对此进行了初步的探讨。     

一些细菌和真菌的解磷能力及其机理初探

4株细菌和8株真菌培养6天后,发现培养液中有机酸含量大幅度增加,PH大幅度地下降,磷的含量大幅度增加,真菌比细菌表现出更强的溶解磷矿粉的能力,不同的微生物分泌有机酸的数量和种类差别很大,菌分泌的有机酸种类比细菌要多。但是,培养液中有机酸总量与解磷量之间并不存在显的相关性。     

DIFFERENCES IN THE OCCURRENCE AND DISTRIBUTION OF HYDROXYPROLINE-PROTEINS AMONG THE ALGAE

Fifty algae from seven phyla have been examined in order to determine whether they contain protein-bound hydroxyproline and whether this hydroxyproline is concentrated in the cell wall. Green algae, with the exception of Nitella, all contain hydroxyproline, and in most cases it is concentrated in the cell wall. Hydroxyproline is also present in low levels in the brown algae, but here it is concentrated in the soluble proteins. Red algae contain no hydroxyproline. The presence of hydroxyproline in blue-green algae is variable, but when present the levels are low. It appears, then, that the major algal phyla differ with respect to the distribution and occurrence of hydroxyproline-proteins.     

败酱科和续断科植物在我国的新记录种

本文报导了我国败酱科和续断科植物3个新记录种,它们是斜冠歧缬草Valerianella plagiostephana Fisch.et C.A.Mey.,块根缬草Valeriana tuberosa Linn.和长叶刺参Morina longifolia Wall.     

THE PIGMENT-PROTEIN COMPOUND IN PHOTOSYNTHETIC BACTERIA : I. THE EXTRACTION AND PROPERTIES OF PHOTOSYNTHIN

1. Photosynthetic bacteria in water suspension break open when treated with supersonic vibration thus liberating the cell contents, including a water soluble protein to which is attached the otherwise water insoluble pigments, bacteriochlorophyll and carotinoids. Both types of pigments appear to be combined with the same protein. 2. The protein pigment compound is insoluble in the region of pH 3.0 to 4.5 and in neutral solution can be completely precipitated by 0.5 saturated (NH₄)₂SO₄. It is soluble in distilled water and adsorbable on fullers'' earth. 3. Supersonic extracts of photosynthetic bacteria do not have the ability to carry on photosynthesis, but will act as a photocatalyst for the oxidation of ascorbic acid with visible or infrared radiation. The rate of the photochemical oxidation is proportional to the light intensity.     

籽粒苋几个品种的光合强度测定

经测定籽粒苋的光合强度显著高于大豆,从美国引进的几个品种的光合强度显著高于国内的品种。成分分析表明籽粒苋含蛋白质丰富,是有潜在开发价值的饲料作物。