Effect of Light on Nonphotosynthetic Microorganisms

The effect of light on the pigmentation of various strains belonging to the genus Streptomyces was investigated. It was revealed that six species of streptomycetes, S. massasporeus, S. phaeopurpureus, S. chibaensis, S. salmonicida, S. fluvissimus and S. longispororuber, were photochromogenic, i.e., these strains can be photoinduced to synthesize pigments. On the basis of these results, pigmentation in Streptomyces is discussed.     

Effect of Gas Hydrate Formers on Microorganisms

VARIOUS BACTERIA, YEASTS, AND MOLDS IMPORTANT TO THE FOOD INDUSTRY WERE INCUBATED IN AEROSOL CANS CONTAINING A C BROTH AND ONE OF THE FOLLOWING THREE GAS HYDRATE FORMERS: propane, dichlorodifluoromethane (f-12), and 1,1-difluoro-1-chloroethane (f-142b). Most hydrate formers were tested at three concentrations: low (vapor state), intermediate (liquid state, low level), and high (liquid state, high level). Samples were continuously agitated for 48 hr at 21 +/- 3 C. Changes in numbers of microorganisms were determined by plate count. With hydrate formers in the vapor state, propane was more toxic to the microorganisms tested than either f-12 or f-142b. The most resistant organisms from these trials were then tested against f-12 or f-142b in the liquid state. Hydrate formers were far more toxic in the liquid state than in the vapor state. With the exception of sporulated cultures of Bacillus cereus, all microorganisms tested were greatly reduced in numbers when agitated for 48 hr at 21 C in the presence of f-12 or f-142b.     

动态磁场下微生物的生物学效应研究

磁场是一种普遍存在的环境因子,但其对微生物的影响尚不清楚.使用超导磁体产生的静态磁场,配以自制实验装置对所选菌株(枯草芽胞杆菌和鼠伤寒沙门氏菌)进行动态磁场处理,比较处理组与地磁场对照组之间包括生长曲线、酶活力等在内的各项生理生化指标,研究动态磁场对微生物的影响.研究发现,动态磁场下两株细菌的生长过程均受到影响.处理组枯草芽胞杆菌对数期提前,衰亡期菌体死亡速率受抑制,碱性蛋白酶活力增加,中性蛋白酶活力降低,而蛋白酶表达量无差异;鼠伤寒沙门氏菌动态磁场处理组对数期推迟,衰亡期菌体死亡亦受到抑制,细菌粘附实验与侵袭力实验表明,细菌毒力相对增强.以上结果表明,动态磁场可对微生物产生影响.并随着微生物种类的不同而异.     

Effect of Microorganisms on In Situ Uranium Mining

The extraction of some metal values, e.g., uranium or copper, may be accomplished by using solutions to remove metals from ore bodies without practicing conventional mining. This process is referred to as in situ leaching and has been used industrially to recover uranium. The growth of microbial populations during in situ leaching is believed to be one of the causes of flow path plugging in the ore body, which results in decreased uranium production. Leach solution and solid samples from well casings and submersible pumps were collected from an in situ mining operation experiencing plugging problems. Bacillus sp., Micrococcus sp., pseudomonads, and xanthomonads were isolated from these samples in concentrations of 10⁵ CFU ml⁻¹. A mixed culture of these organisms was inoculated into a uranium core specimen in the laboratory to assess the role of microbes in the plugging problem. A one-third decrease in permeability was effected in 16 days. Hydrogen peroxide (0.2 g liter⁻¹) killed the microorganisms in the core and alleviated the plugging problem. Periodically injecting hydrogen peroxide into the ore body through the production wells may reduce microbial plugging problems.     

Effect of Gamma-Ray upon Food Microorganisms

The author has carried out a study concerning a simplified method for the measurement of gamma-ray resistivity of E. coli. This report deals with comparison of each survival curve of 11 species of bacteria and the influence of addition of chemicals on a medium containing E. coli by gamma-ray irradiation by application of this method.     

Effect of Gamma-Ray upon Food Microorganisms

Possibility of enhancement in the lethal effect of gamma-ray by the aid of various substances was investigated. This report deals with the survival-ratios of four strains of bacteria in the nutrient or the non-nutritious pure agar medium, to which various kinds of preservatives or antibiotics were added.     

Effect of Gamma-ray upon Food Microorganisms

The influences of some environmental physical conditions during irradiation upon the survival of bacteria were investigated. This report deals with the effect of the secondary ray from the metallic foil and the influence of the irradiation in frozen state on survivals of bacteria.     

Effect of Microorganisms and Microbial Metabolites on Apatite Dissolution

The dissolution rate of apatite was determined in batch reactors in organic acid solutions and in microbial cultures. Inoculum for the cultures was from biotite plus apatite crystals from a granite weathering profile in South Eastern Australia. In both the biotic and the abiotic experiments, etching of the apatite surface leads to the formation of elongated spires parallel to the c axis. Apatite dissolution rates in the inorganic, acetate, and oxalate solutions increase as pH decreases from approximately 10 -11 mol/m -2 · s -1 at initial pH 5.5 to 10 -7 mol/m -2 · s -1 at initial pH 2. Under mildly acidic to near neutral pH conditions, both oxalate and acetate increased apatite dissolution by up to an order of magnitude compared to the inorganic conditions. Acetate catalyzed the reaction by forming complexes with Ca, either in solution or at the mineral surfaces. Oxalate forms complexes with Ca as well, and can also affect reaction rates and stoichiometry by forming Ca-oxalate precipitates, thus affecting solution saturation states. In all abiotic experiments, net phosphate release to solution approaches zero even when solutions are apparently undersaturated by several orders of magnitude with respect to the solubility of an ideal fluoroapatite mineral. In the microbial experiments, two enrichment cultures increased both apatite and biotite dissolution by producing organic acids, primarily pyruvate, fermentation products, and oxalate, and by lowering bulk solution pH to between 3 and 5. However, the microorganisms were also able to increase phosphate release from apatite (by two orders of magnitude) without lowering bulk solution pH by producing pyruvate and other compounds.     

Effect of Irradiation on Microorganisms in a Nuclear Reactor

The effects of irradiation in the JRR-1 (Japan Research Reactor No. 1, a homogeneous light water nuclear reactor; max. power, 50 KW) on microorganisms such as bacterial and fungal spores and yeast cells were investigated in comparison with those of ⁶⁰Co gamma radiation. As far as the lethal effect was concerned the dose rate of radiation in the experimental hole No. 16 of the JRR-1 was equivalent to 3.0×l0⁶~3.4×l0⁶ r/hr with ⁶⁰Co gamma radiation, and a ratio of the neutron effect to the gamma radiation effect on microorganisms in this hole was estimated to be approximately 3~5.4. The results different from those with gamma radiation were obtained in experiments such as post-NaCl treatment and spore germination. The considerable contribution of fast neutrons to the total biological effect of neutrons, in comparison with the thermal neutron effect, could be presumed from the microbiological experiments with the help of physical and chemical data. Morphological changes in post-irradiation growth were observed by means of phase contrast microscopy. No specific aftereffect was found.     

Effect of Gamma-ray upon Food Microorganisms

The author has carried out a series of studies on the effects of various conditions on the survival of E. coli irradiated with cobalt-60 gamma-ray. This report deals with the survivals of the strain irradiated in the medium containing each of the components of various types of fish-meats and meats.     

黄荆叶提取液抑菌作用的研究

用黄荆叶的乙醇提取物对 6种细菌、2种酵母菌、3种霉菌三大类微生物进行抑菌实验 ,得出其最低抑菌浓度 (MIC)。由结果推断出黄荆叶提取物不失为一种良好的天然抗菌剂 ,可添加于食品和药物中     

Effect of Four Nematocides on Activities of Microorganisms in Soil

Tests were conducted to determine the effects of four nematocides, Dasanit, carbofuran, D-D, and Vorlex on microbial activities in a loamy sand. The results indicated that bacterial and fungal populations initially decreased with some nematocide treatments but recovered rapidly to levels similar to those in the controls. In some instances, ammonium production from added peptone increased in the nematocide-treated soils, whereas mineralization of soil organic nitrogen and nitrification and oxidation of elemental sulfur were depressed. Oxygen consumption generally increased in proportion to the concentration of nematocide in the soil. However, with Vorlex, an increase in respiration was evident at the lower concentration, whereas an inhibitory effect occurred at the higher concentration. The study indicated that indigenous soil microorganisms can tolerate these chemicals used for control of nematodes in soil.     

外源微生物及辅料对秸秆降解效果的影响

研究加入外源微生物及添加辅料对秸秆降解率的影响。通过秸杆固体培养进行了降解试验,结果显示,加入外源微生物后纤维素降解率明显提高,嗜热侧孢霉可提高34.76%,放线菌可提高18.99%。通过在秸秆中加入辅料香菇菌糠,培养后秸秆的纤维素含量由原来的32.11%降至14.19%,降解率达55.81%。加入外源微生物的秸秆降解过程具有升温快、温度高及高温维持时间长等优点。加入微生物的秸秆降解高温维持8 d,对照为6 d。秸秆降解过程中的最高温度分别为63℃和58℃。为下一步外源微生物的进一步研究及菌糠的大量利用提供参考。     

Effect of Nitrofurans and Chlortetracycline on Microorganisms Associated with Shrimp

Nitrofuran AF-2 displayed greater inhibitory effect than did nitrofuran Z when a mixed bacterial culture, including several proteolytic bacteria, isolated from shrimp was subjected to these compounds in vitro. Nitrofuran Z exhibited greater bactericidal properties than did chlortetracycline in all cultures used. Only 10 mug of nitrofuran AF-2 per ml was sufficient to inhibit the growth of mixed bacteria in nutrient broth, whereas 50 mug of nitrofuran Z per ml was necessary to accomplish the same inhibition. A 50-mug amount of chlortetracycline per ml displayed about the same inhibitory effect as either 10 mug of AF-2 per ml or 20 mug of Z per ml. The isolated proteolytic bacteria showed greater suppression of growth when subjected to AF-2 than when subjected to Z; however, both nitrofurans were effective in preventing growth. The addition of either 1 mug of AF-2 per ml or 5 mug of Z per ml to nutrient broth inhibited the growth of Achromobacter aquarmarinus, whereas chlortetracycline was less effective, requiring about 20 mug to suppress growth to the same degree.     

Factors Affecting the Toxic Effect of Tin on Estuarine Microorganisms

Inorganic tin (SnCl₄·H₂O) is toxic to microbial populations obtained from estuarine sediments plated on nutrient medium solidified with either agar or purified agar. The use of gelatin as a gelling agent decreased the apparent toxicity of tin, and toxicity was markedly reduced in medium solidified with silica gel. There was no evidence that toxic agar-tin complexes were involved. Cd, Cu, Pb, Ni, and Zn exhibited similar toxicity patterns; therefore, toxicity levels determined in the laboratory should be extrapolated to the environment with caution. The addition of cysteine to the medium had no effect on tin toxicity. Serine or 3-hydroxyflavone enhanced toxicity, while humic acids or gelatin inhibited toxicity. Replacement of SO₄²⁻ with NO₃⁻ did not alter tin toxicity, but replacement of Cl⁻ with NO₃⁻ decreased tin toxicity. Thus, the toxic effect(s) of tin depend as much on the chemical speciation of the metal as on the total concentration of the metal in the medium.     

紫甘薯花色苷色素的抑菌作用研究

本文研究了紫甘薯花色苷色素抑制大肠杆菌、金黄色葡萄球菌、啤酒酵母和黑曲霉的作用及机理。结果表明：紫甘薯花色苷色素对大肠杆菌及金黄色葡萄球菌均有抑制作用, 并与其浓度呈正相关, 而对啤酒酵母和黑曲霉无抑制作用。透射电镜观察和大肠杆菌生长曲线表明, 该色素的抑菌作用可能是通过增强细胞膜的通透性, 使细胞异常生长, 抑制对数生长期的细胞分裂, 使细胞质稀薄、细胞解体。SDS-PAGE 分析表明, 紫甘薯花色苷对大肠杆菌蛋白表达影响不明显, 未见特征性条带的消失, 仅对部分蛋白质合成量有影响。     

紫甘薯花色苷色素的抑菌作用研究

本文研究了紫甘薯花色苷色素抑制大肠杆菌、金黄色葡萄球菌、啤酒酵母和黑曲霉的作用及机理.结果表明:紫甘薯花色苷色素对大肠杆菌及金黄色葡萄球菌均有抑制作用,并与其浓度呈正相关,而对啤酒酵母和黑曲霉无抑制作用.透射电镜观察和大肠杆菌生长曲线表明,该色素的抑菌作用可能是通过增强细胞膜的通透性,使细胞异常生长,抑制对数生长期的细胞分裂,使细胞质稀薄、细胞解体.SDS-PAGE分析表明,紫甘薯花色苷对大肠杆菌蛋白表达影响不明显,未见特征性条带的消失,仅对部分蛋白质合成量有影响.     

Effect of Zytron and Its Degradation Products on Soil Microorganisms

There was no adverse effect of Zytron, o-2,4-dichlorophenyl o-methyl isopropyl phosphoramidothioate, a herbicide, upon molds, actinomycetes, and soil bacteria in field plots, or upon selected soil microorganisms in model systems. 2,4-Dichlorophenol, a degradation product, was found to be toxic at levels above 10 ppm to molds, but levels this high were not found in soil from treated plots. Aspergillus clavatus degraded both Zytron and 2,4-dichlorophenol. Sodium o-methyl isopropyl phosphoramidothioate, another degradation product of Zytron, stimulated the growth of a species of Penicillium.