He-Ne激光辐照酿酒酵母菌的诱变效应

本文应用ＨｅＮｅ激光对甘蔗糖蜜工业性生产用酿酒酵母菌ＳａｃｃｈａｒｏｍｙｃｅｓｃｅｒｅｖｉｓｉａｅＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,对产乙醇含量进行了气相色谱分析,发现ＨｅＮｅ激光对酿酒酵母菌具有明显的生物刺激效应和可能的诱变作用,并初步筛选到产乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的分析,进一步证实了ＨｅＮｅ激光对酿酒酵母菌的诱变作用。这就为工业上利用Ｈｅ－Ｎｅ激光对酿酒酵母菌进行诱变育种展现新的前景。     

C02激光辐照对酿酒酵母菌的诱变作用

应用红外ＣＯ_２激光对甘蔗糖蜜工业性生产用酿酒酵母菌Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ ＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,发现红外ＣＯ_２激光对酿酒酵母菌具有诱变作用,并初步筛选到产乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的比较分析,进一步证实了红外ＣＯ_２、激光对酿酒酵母菌的诱变作用．从而为工业上利用红外ＣＯ_２激光对酿酒酵母菌进行诱变育种展现新的前景。     

CO2激光辐照对酿酒酵母菌的诱变作用

应用红外ＣＯ２激光对甘蔗糖蜜工业性生产用酿酒酵母菌Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ ＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,发现红外ＣＯ２激光对酿酒酵母菌具有诱变作用,并初步筛选到决乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的比较分析,进一步证实了红外ＣＯ２激光对酿酒酵母酶的诱变作用。从而为工业上利用红外ＣＯ２激光对酿酒酵母菌进     

CO2激光辐照对酿酒酵母菌的诱变作用*

应用红外ＣＯ_２激光对甘蔗糖蜜工业性生产用酿酒酵母菌Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ ＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,发现红外ＣＯ_２激光对酿酒酵母菌具有诱变作用,并初步筛选到产乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的比较分析,进一步证实了红外ＣＯ_２、激光对酿酒酵母菌的诱变作用．从而为工业上利用红外ＣＯ_２激光对酿酒酵母菌进行诱变     

曲酸产生菌激光诱变效应的研究

采用经紫外线(UV)、^60Co、亚硝基胍(NTG)复合诱变得到的黄曲霉曲酸产生菌(UCN7—12),进行激光诱变处理。研究证实在经过UV、^60Co、NTG诱变处理后,黄曲霉突变株用He—Ne激光与YAG激光进行诱变处理仍能提高产酸率,其中He—Ne激光辐照处理20min,正变率为12．1％,产量提高约13％。YAG激光辐照处理300sec,正变率16．7％,产量提高18．3％。说明上述两种激光对黄曲霉曲酸产生菌有一定的诱变效应。     

激光诱变洋葱生理效应研究Ⅱ

采用CO2和He-Ne两种激光的三种剂量,分别辐照两个洋葱品种的湿种子,采用生理生化的方法,从净同化率,净光合速率,呼吸速率,蛋白质含量等四个方面研究洋葱各处理的生物学效应。结果表明：He-Ne激光辐照洋葱的净同化率,净光合速率,呼吸速率,蛋白质含量的变异大于CO2激光辐照,采用He-Ne激光辐照洋葱容易从其变异后代中选择出高产,优质的优良变异株,进而育成符合育种目标的优良新品种。     

枯草杆菌SOD高产菌株的诱变选育及产酶条件研究

本实验采用低能氮离子注入技术对枯草芽孢杆菌(Bacillus subtilis)进行辐照诱变处理,选育出一株SOD高产菌株(编号为BsB8)。其生物量略高于出发菌株、SOD产量达3439．3U／g湿菌体,为实验出发菌的1．88倍。该菌株最佳产酶条件为：起始pH为8．2,装液量为150ml／500ml,接种量为1．5％;添加Mn^2 的培养基可显著提高SOD酶活。     

激光复合诱变选育叶酸高产菌

利用高效液相色谱测定发酵液中叶酸含量,比较产朊假丝酵母(Candida utilis)、异常汉逊酵母(ftan-senula anomala)和枯草芽孢杆菌(Bacillus subtilis)产叶酸能力的高低,从而确定生产叶酸的最佳菌种.出发菌株经紫外照射诱变后,再采用激光复合诱变方式进行进一步的筛选,并对其传代稳定性进行研究,以期进一步获得稳产高产叶酸产生菌突变株.结果表明产朊假丝酵母产叶酸量最高.紫外照射3 min得到的Y1.4菌株产叶酸量与原始菌株相比,产量提高了33.8%.激光一紫外复合诱变后筛选出4株产量较高的菌株,其中以Y2.12产量最高.Y2.12产叶酸量与原始菌株相比,提高了65.8%.经传代培养分析,Y2.12诱变株的产量稳定.该结果表明,激光复合诱变是获得高产叶酸的有效途径.     

N+注入和60Co-γ辐照对柠檬酸发酵菌黑曲霉的诱变效应

首次尝试了应用两种核技术手段(同时)对黑曲霉进行诱变,即将大剂量^60Co-γ辐照的黑曲霉孢于直接进行低能氮离子注入,使处于休眠状态下的黑曲霉抱子同时受至^60Co-γ辐照和N^ 注入的作用。通过溴甲酚绿指示性平板辅助筛选和摇瓶发酵。获得了1株产酸提高18．44％、转化率达1034．5％的M3代菌株CN05,为柠檬酸发酵菌黑曲霉的进一步育种工作提供了诱变参数和高产出发菌株。     

高产Y-氨基丁酸酵母菌株的亚硝基胍诱变选育

目的：探讨亚硝基胍诱变选育高产Y-氨基丁酸酵母菌株的方法。方法：使用亚硝基胍对酵母菌株进行诱变;采用含溴甲酚绿的YEPD培养基筛选突变菌,采用薄层层析法和比色法鉴定变异菌株发酵液中的Y-氨基丁酸及其含量;对突变菌株连续继代培养4代,测定各代发酵液中Y-氨基丁酸的含量,鉴定诱变菌株的遗传稳定性：结果：亚硝基胍诱变酵母的最佳浓度为1．0g．L^-1,最佳诱变时间为15min;获得了5株突变菌株,菌落呈绿色;薄层层析法鉴定突变菌株都能产Y-氨基丁酸;诱变菌发酵液中的Y-氨基丁酸含量各异,但高于对照,且增长幅度很大;对突变菌株后代遗传稳定性进行了鉴定,结果表明突变菌株4遗传性较稳定。结论：采用1．0g．L^-1的亚硝基胍溶液处理酵母菌15min,经筛选鉴定,获得了一株遗传稳定的高产Y-氨基丁酸的酵母菌株。     

Modulation of perception and neurophysiological correlates of brief CO2 laser stimuli in humans using concurrent large fiber stimulation

It has been postulated that peripheral large fiber stimulation could modulate pain perception, probably by gating the input from AS-and C-fibers. The present study examined the effects of concurrent large fiber stimulation on the perception and neurophysiological correlates of brief CO2 laser stimuli known to activate A- and C-nociceptor endings selectively. Four test stimuli of brief non-painful and painful CO2 laser pulses (duration 50 ms; diameter 5 mm; intensity range 0.116-0.212J) were delivered at random every 5-10s on the dorsum of the left forearm of ten healthy subjects. Large fiber stimulation was performed by a dynamic soft brush applied either adjacently to test stimuli (segmental brush condition) or on the dorsum of the contra-lateral foot (extrasegmental brush condition). Perception, reaction time (RT) and laser-evoked potentials (EPs) were examined for conditions with brush and without brush (control condition). The signal detection theory (SDT) was used to evaluate the discrimination performance and the decision criterion. During extrasegmental brushing, these variables were unaffected as compared with control conditions. During segmental brushing, the absolute detection threshold increased, the probability of detection decreased and the RT increased. Interestingly, the stimulus-response curve of detected stimuli and late LTPs did not change significantly. SDT analysis showed that segmental brushing did not change the discrimination performance or sensitivity but increased significantly the subject's decision criterion for reporting sensation. It was concluded that segmental brushing acted primarily at supra-spinal levels and not by gating the input from small primary afferents activated selectively by brief CO2 laser stimuli.     

Isolation, characterization, and fermentative pattern of a novel thermotolerant Prototheca zopfii var. hydrocarbonea strain producing ethanol and CO2 from glucose at 40 °C

A novel thermotolerant strain of the achlorophyllous micro-alga Prototheca was isolated from a hot spring. The isolate was found to produce an appreciable amount of ethanol and CO2 from glucose under anoxic conditions at both 25 and 40 degrees C; this type of alcohol fermentation has not yet been reported in the genus Prototheca. Moreover, it also evolved gas from sucrose after a time lag at 40 degrees C. Its taxonomic characteristics coincided with those of Prototheca zopfii var. hydrocarbonea, and phylogenetic analysis, based on a small-subunit (SSU) rDNA sequence, also revealed a close relationship between the two strains. D-lactic acid, ethanol, CO2 and a trace of acetic acid were produced from glucose, but L-lactic acid, formic acid, and H2 were not. At 25 degrees C, D-lactic acid and ethanol were produced in approximately equimolar amounts under N2/H2/CO2, whereas ethanol production was predominant under N2. More ethanol was produced at 40 degrees C than at 25 degrees C irrespective of the gas composition in the atmosphere. This is the first report on gas production from glucose and on the changes in the fermentative patterns as a function of temperature for the genus Prototheca.     

Co-metabolism of citrate and glucose by Leuconostoc spp.: effects on growth, substrates and products

Growth, substrate utilization and product formation from glucose, citrate and a mixture of both substrates were studied in four strains of Leuconostoc spp. Citrate was not used as an energy source but was rapidly metabolized when glucose was present. The predictable amounts of D-lactate and ethanol were produced from glucose, although strains X2 and 7–1 gave lower yields of ethanol. In strains NCW1, S3 and X2, co-metabolism of both glucose and citrate resulted in stimulation of growth, decreased uptake of glucose, increased acetate and D-lactate production and lack of ethanol production compared with that obtained with glucose alone. Strain 7–1 showed only growth stimulation and increased acetate production. Diacetyl, acetoin or 2, 3-butylene glycol were not detected. In strain NCW1 citrate had a slightly inhibitory effect on the enzymes of the 'ethanol' leg of glucose metabolism. Except for strain 7–1, these observations are consistent with a switch in glucose metabolism from ethanol to acetate production.     

Strain and sex differences in repeated ethanol treatment-induced motor activity in quasi-congenic mice

The B6.C quasi-congenic Recombinant QTL Introgression (RQI) strains of the b4i5 series have similar genetic background, but differ in about 5% of their genome from the C57BL/6ByJ (B6) background strain because they carry short chromosome segments introgressed from the BALB/cJ (C) donor strain. These RQI strains were derived from mouse lines selectively bred for high activity of mesencephalic tyrosine hydroxylase (TH/MES), therefore genetic variation in dopamine system-related behaviours, such as ethanol-induced motor activity, can be expected. Males and females of 17 RQI and two progenitor strains were tested for initial motor activity for 15 min after a habituating injection of saline, which was followed by an i.p. injection of saline or ethanol (2 g/kg) and an additional test of motor activity for 30 min. This procedure was repeated during 4 subsequent days. In all strains, the first-day ethanol treatment showed an inhibitory effect. With repetition of the treatment the inhibitory effect decreased, and a stimulatory effect could be observed with significant strain- and sex-dependent variation. Females exhibited higher activity in the saline group than males, and reached an equilibrium of inhibition and stimulation sooner than males with repetition of the ethanol treatment. The highest (> 25-fold) difference in activity after repeated ethanol treatment was detected between females of the two strains B6.Cb4i5-Alpha4/Vad and B6.Cb4i5-Beta13/Vad. These results firstly suggest that females are more sensitive to repeated ethanol exposure than males, secondly they support the observations that ethanol has both inhibitory and stimulatory effects on motor activity, which are affected by sex, genotype, and repetition of treatment, and thirdly offer new quasi-congenic animal models with highly different responses to ethanol allowing one to more quickly move to gene detection.     

Conformational modulation of human cytochrome P450 2E1 by ethanol and other substrates: a CO flash photolysis study

The alcohol-inducible cytochrome P450 2E1 is a major human hepatic P450 which metabolizes a broad array of endogenous and exogenous compounds, including ethanol, low-molecular weight toxins, and fatty acids. Several substrates are known to stabilize this P450 and inhibit its cellular degradation. Furthermore, ethanol is a known modulator of P450 2E1 substrate metabolism. We examined the CO binding kinetics of P450 2E1 after laser flash photolysis of the heme-CO bond, to probe the effects of ethanol and other substrates on protein conformation and dynamics. Ethanol had an effect on the two kinetic parameters that describe CO binding: it decreased the rate of CO binding, suggesting a decrease in the protein's conformational flexibility, and increased the photosensitivity, which indicates a local effect in the active site region such as strengthening of the heme-CO bond. Other substrates decreased the CO binding rate to varying degrees. Of particular interest is the effect of arachidonic acid, which abolished photodissociation in the absence of ethanol but had no effect in the presence of ethanol. These results are consistent with a model of P450 2E1 whereby arachidonic acid binds along a long hydrophobic binding pocket and blocks exit of CO from the heme region.     

Ethanol production from H2 and CO2 by a newly isolated thermophilic bacterium, Moorella sp. HUC22-1

The thermophilic bacterium, Moorella sp. HUC22-1, newly isolated from a mud sample, produced ethanol from H(2) and CO(2) during growth at 55 degrees C. In batch cultures in serum bottles, 1.5 mM ethanol was produced from 270 mM H(2) and 130 mM CO(2) after 156 h, whereas less than 1 mM ethanol was produced from 23 mM fructose after 33 h. Alcohol dehydrogenase and acetaldehyde dehydrogenase activities were higher in cells grown with H(2) and CO(2) than those grown with fructose. The NADH/NAD(+) and NADPH/NADP(+) ratios in cells grown with H(2) and CO(2) were also higher than those in cells grown with fructose. When the culture pH was controlled at 5 with H(2) and CO(2) in a fermenter, ethanol production was 3.7-fold higher than that in a pH-uncontrolled culture after 220 h.     

Effect of osmolarity and dehydration on alginate production by fluorescent pseudomonads

Alginate is produced as an exopolysaccharide by many fluorescent pseudomonads. However, pseudomonads often have a nonmucoid phenotype in standard laboratory media. Growth in the presence of 0.3M sodium chloride or 3–5% ethanol reportedly can lead to the generation of mucoid variants of nonmucoid strains ofPseudomonas aeruginosa. We wished to determine whether alginate production by other fluorescent pseudomonads is affected by sodium chloride and ethanol. Eight alginate-producing strains of saprophytic and phytopathogenic pseudomonads were grown as broth cultures containing 0–0.7M sodium chloride or 0–5% ethanol for 24–30 h at 28° or 35°C. Culture supernatant fluids were subjected to ethanol precipitation, and the amount of alginate present was estimated by measuring the uronic acid content. The presence of sodium chloride and ethanol caused significant stimulation of alginate production by all strains tested exceptP. viridiflava ATCC 13223 andP. fluorescens W4F1080. The optimal concentration of sodium chloride ranged from 0.2 to 0.5M; that for ethanol ranged from 1 to 3%. Moreover, inclusion of the nonmetabolizable, nonionic solute sorbitol showed a similar stimulation of alginate production. The stimulation of alginate production by high medium osmolarity and dehydration appears to be a trait shared by fluorescent pseudomonads.Reference to brand or firm name does not constitute endorsement by the U.S. Department of Agriculture overothers of a similar nature not mentioned.     

Comparison of various atmospheric conditions for isolation and subcultivation of Mycoplasma hyorhinis from cell cultures

The efficiency of aerobic incubation was compared with incubation under various oxygen and carbon dioxide conditions for the isolation and subcultivation of three strains of Mycoplasma hyorhinis from VERO-cell cultures and subcultivation of three laboratory strains. Under anaerobic conditions with a low oxidation-reduction potential (at or below -115 mV) as obtained in jars, with catalysts, containing mixtures of 5%-10% CO2 in H2, very poor or no growth of any of the six M. hyorhinis strains was observed. When traces of oxygen were present (that is, under conditions with higher oxidation-reduction potentials, e.g. when omitting the catalyst in the above gas mixtures or in 5% CO2 + 95% N2) isolation from cell cultures was successful in most tests, but subcultivation of these primary isolates was seldom possible under these semi-anaerobic conditions. However, in most cases these primary isolates could be subcultivated aerobically, although aerobic conditions were unsatisfactory for isolation in about half of the experiments. Isolation of M. hyorhinis was optimal in 5% O2 + 95% N2, under which condition the isolates could also always be subcultivated. Isolation failed occasionally when 5% O2 + 5% CO2 + 90% N2 was used, thus indicating that 5% CO2 was slightly inhibitory. 5% CO2 in air and 10% CO2 either in air, H2 or N2 were also inadequate for isolation from cell cultures. In contrast to the findings with these cell culture-adapted M. hyorhinis strains, the laboratory strains could be subcultivated easily under all conditions tested except those with an oxidation-reduction potential at or below -115 mV; 100% CO2 was inhibitory for all 6 strains. Our findings may partly explain why M. hyorhinis is often considered "non-cultivable" on artificial media once adapted to cell cultures. The findings emphasize the need to employ also a micro-aerophilic condition (5% O2 in 95% N2) in the examination of cell cultures for mycoplasma.