Brom Cresol Green and Brom Phenol Blue as Indicators of Respiration Deficiency in Yeast

Strains of Saccharomyces which contained cells of respirationally normal (wild-type) and of respiration-deficient (RD) mutants were grown on untrient agar plates containing 20-23 mg/liter of either brom cresol green (BCG) or brom phenol blue (BPB). Glucose content of the media was varied experimentally in the range of 1.5-6%. After 2-4 days of incubation, normal colonies were very palely stained whereas RD colonies were drak green with BCG and dark blue with BPB. Optimum glucose content in the medium was 2-3% for S. cerevisiae, S. carlbergensis and S. chevalieri, but Fleischmann's (baker's) yeast developed the best color contrast with 4-5% glucose.     

2-ketogluconic acid production and phosphate solubilization by Enterobacter intermedium

Enterobacter intermedium, isolated from grass rhizosphere, exhibited a strong ability to solubilize insoluble phosphate. This bacterium oxidized glucose to gluconic acid and sequentially to 2-ketogluconic acid (2-KGA), which was identified using HPLC and GC-MS. The ability of E. intermedium to solubilize phosphate and produce 2-KGA produce in broth medium containing different components was monitored with air and without air supply. With an air supply, the production of 2-KGA markedly increased to about 110 g/l at day 10 in media containing 0.2 M gluconic acid, while it was about 65 g/l without gluconic acid addition. With an air supply, the concentration of soluble phosphate significantly decreased to 200-250 mg/l in media containing 1% CaCO3, whereas it was about 1000 mg/l without CaCO3 addition. Without an air supply, the concentration of 2-KGA and phosphate were negligible throughout the culture period.     

Optimization of a medium for enhancing nicotine biodegradation by Ochrobactrum intermedium DN2

AIMS: To optimize a medium for nicotine degradation by Ochrobactrum intermedium DN2 in presence of yeast extract, glucose and Tween 80 using response surface methodology (RSM). METHODS AND RESULTS: In this study, the effects of yeast extract, glucose and Tween 80 on nicotine degradation were investigated in flasks using a novel nicotine-degrading bacterium, O. intermedium DN2. A full factorial central composite design was applied in the design of experiments and in the analysis of the experimental data. The results showed that the most significant variable influencing nicotine degradation was yeast extract, followed by glucose, and then Tween 80. Moreover these three factors interacted with each other and combined to produce positive effects on nicotine degradation. The experimental data also allowed the development of an empirical model (P < 0.0001) describing the inter-relationship between independent and dependent variables. By solving the regression equation, the optimal values of the variables were determined as: yeast extracts 0.094%, glucose 0.101% and Tween 80 0.080%. Using the medium obtained, about 1,220 mg l(-1) of nicotine was degraded (95.55%) within 10 h at the specific biodegradation of 116.59 mg l(-1) h(-1) in 30-l bioreactor containing 25-l tobacco extract. CONCLUSIONS: An optimal medium of nicotine degradation by the strain DN2 was obtained. SIGNIFICANCE AND IMPACT OF THE STUDY: RSM proved to be reliable in developing the model, optimizing factors and analysing interaction effects. The results provide better understanding on the interactions between yeast extract, glucose and Tween 80 for nicotine biodegradation.     

Ochrobactrum intermedium ANKI, a nitrogen-fixing bacterium able to decolorize azobenzene

Morphological and biochemical properties of the nitrogen-fixing strain Ochrobactrum intermedium ANKI, intensely growing on media with azo compounds, and its resistance to various common xenobiotics were investigated. The kinetics of azobenzene conversion by O. intermedium ANKI was studied. Under cometabolism conditions, up to 40 mg of azobenzene per liter of medium were decolorized within one week. It was shown that the strain possessed molybdenum-dependent nitrogenase activity, and its nitrogenase system was sensitive to oxygen and fixed nitrogen in the medium.     

Inactivation of pqq genes of Enterobacter intermedium 60-2G reduces antifungal activity and induction of systemic resistance

Enterobacter intermedium 60-2G, a phosphate solubilizing bacterium, has the ability to induce systemic resistance in plants against soft rot pathogen Erwinia carotovora. Glucose dehydrogenase, an enzyme that utilizes pyrroloquinoline quinone (PQQ) as a cofactor, is required for the synthesis of gluconic acid by E. intermedium 60-2G. Here, we report that the pqqA and pqqB genes are required for phosphate solubilization and induced systemic resistance against a soft rot pathogen in tobacco. Mutations in either the pqqA or pqqB gene abolished the production of 2-ketogluconic acid and eliminated the ability of E. intermedium to solubilize hydroxyapatite. Addition of gluconic acid to the growth media restored the ability of the pqqA mutant to produce 2-ketogluconic acid. Interestingly, both pqqA and pqqB mutants of E. intermedium lost their ability to inhibit the growth of the rice pathogen Magnaporthe grisea KI-409. Additionally, induced systemic resistance against the soft rot pathogen was attenuated in the pqq mutants. These functions were restored by complementation with the wild-type pqq gene cluster. Our findings suggest that PQQ plays an important function in beneficial traits including phosphate solubilization, antifungal activity, and induced systemic resistance of E. intermedium, possibly by acting as a cofactor for several enzymes including glucose dehydrogenase.     

The effects of magnesium and calcium ions on phosphatase activities at alkaline pH in the molar region of newborn mice

Summary The hydrolysis of ATP, AMP and glycerophosphate (GP) at alkaline pH in mineralizing bone and teeth of young mice has been studied histochemically. The substrates were visibly hydrolyzed to the same degree in osteoblasts, cells of stratum intermedium, odontoblasts and subodontoblasts at Ca²⁺ concentrations ranging from 10 mM to 600 mM. In the ameloblasts, however, only ATP was hydrolyzed. The ATPase activities gradually decreased at increasing Mg²⁺/Ca²⁺ ratios. The AMPase and GPase activities, on the other hand, were visibly unaffected. Marked cellular staining, including the nuclei was seen with AMP and GP as substrates when only Mg²⁺ ions were added. No ATPase activity at all could be recorded in media containing Mg²⁺ but no Ca²⁺ ions. The different phosphatase activities in cells involved in hard tissue formation were identically affected by preincubations with solutions containing various concentrations of Ca²⁺ or Mg²⁺ ions. The ATPase activity in striated muscle fibres and blood vessel walls, however, was affected differently by the same procedure.The results indicate that the phosphatase activities recorded in osteoblasts, cells of stratum intermedium, odontoblasts and subodontoblasts at alkaline pH belong to one single enzyme. The results also imply that CaATP is the preferred substrate in the enzymatic hydrolysis of ATP in hard-tissue-forming cells.     

应用分子原位杂交技术解析小麦-天兰冰草部分双二倍体──远中2号的染色体构成

为分析普通小麦（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ）－天兰冰草（Ａｇｒｏｐｙｒｏｎｉｎｔｅｒｍｅｄｉｕｍ）部分双二倍体──远中２号（２ｎ＝５４）的染色体构成,用生物素（ｂｉｏｔｉｎ－１６－ｄＵＴＰ）标记天兰冰草染色体组ＤＮＡ作为探针,以普通小麦品种中国春染色体组ＤＮＡ为封闭ＤＮＡ（ｂｌｏｃｋｉｎｇＤＮＡ）,与远中２号的有丝分裂中期染色体ＤＮＡ进行了分子原位杂交。证明远中２号除具有普通小麦的２１对染色体外,附加了１对小麦－天兰冰草易位染色体（即天兰冰草染色体片段易位到小麦染色体的两臂端部）、５对天兰冰草染色体。说明小麦－天兰冰草部分双二倍体在形成过程中染色体行为是比较复杂的,不仅可能产生小麦－天兰冰草染色体间易位,而且小麦染色体也可能与天兰冰草染色体的３种染色休组染色体共同参与组建新的染色体组附加到小麦中去。     

利用细菌还原有毒Cr(Ⅵ)为Cr(Ⅲ)

Overthelastfewdecadesenvironmentalcontaminationwithheavymetalshasincreaseddrastically .Heavymetalsfoundinwastewatersareharmfultotheenvironmentandtheireffectsonbiolo gicalsystemareverysevere.Anefficientandcheaptreatmentfortheirremovalandreuseofspentmetalsfromwastewaterneedstobedeve loped .Theremovaloftoxicmetalsfromtheenvironmentbymi croorganismshaspotentialasaneffectivemeansofremediatingheavymetalswastes.Microbe basedtechnologiescanprovideanalternativetoconventionalmethodsformetalremoval[1 ] .…     

应用原位杂交及RAPD技术标记抗黄矮病小麦一中间偃麦草染色体异附加系

以生物素（Ｂｉｏｔｉｎ－１６－ｄＵＴＰ）标记中间偃麦草基因组 ＤＮＡ为探针,与抗黄矮病小麦－中间偃麦草染色体异附加系Ｚ６进行原位杂交,鉴定出附加的１对中间偃麦草染色体。对异附加系 Ｚ６和 Ｌ１及它们的小麦亲本进行了 ＲＡＰＤ分析,从 １２０个随机引物中,筛选出 ２个引物可以扩增出附加染色体的特异ＤＮＡ片段,可作为鉴定寻人小麦的中间偃麦草染色质的分子标记。     

Studies on the effects of carbon:nitrogen ratio, inoculum type and yeast extract addition on jasmonic acid production by Botryodiplodia theobromae Pat. strain RC1

Jasmonic acid is a native plant growth regulator produced by algae, microorganisms and higher plants. This regulator is involved in the activation of defence mechanisms against pathogens and wounding in plants. Studies concerning the effects of carbon: nitrogen ratio (C/Nr: 17, 35 and 70), type of inoculum (spores or mycelium) and the yeast extract addition in the media on jasmonic acid production by Botryodiplodia theobromae were evaluated. Jasmonic acid production was stimulated at the carbon: nitrogen ratio of 17. Jasmonic acid productivity was higher in the media inoculated with mycelium and in the media with yeast extract 1.7 and 1.3 times, respectively.     

Some observations on oscillatory changes in the growth rate of Saccharomyces cerevisiae in aerobic continuous undisturbed culture.

Oscillatory changes in the growth rate were observed in undisturbed continuous culture of Saccharomyces cerevisiae on sugar-cane molasses media when nitrogen sources (2.56 to 6.17 g/liter of ammonium sulfate or 1.22 g/liter of urea) were added to the feeding mash and when the air rate was 1.3 to 1.6 v/v/m. The oscillations were not affected by the addition of yeast extract. The suppression of the nitrogen source during the continous test leads to a nonoscillatory transient state. No oscillations occured at all when no nitrogen source was added to the medium and/or the air rate was equal to zero or equal to about 3.3 v/v/m. The oscillatory responses of the system were affected by a previous anaerobic continuous cultivation of the yeast.     

C. albicans increases cell wall mannoprotein, but not mannan, in response to blood, serum and cultivation at physiological temperature

The cell wall of Candida albicans is central to the yeasts ability to withstand osmotic challenge, to adhere to host cells, to interact with the innate immune system and ultimately to the virulence of the organism. Little is known about the effect of culture conditions on the cell wall structure and composition of C. albicans. We examined the effect of different media and culture temperatures on the molecular weight (Mw), polymer distribution and composition of cell wall mannan and mannoprotein complex. Strain SC5314 was inoculated from frozen stock onto yeast peptone dextrose (YPD), blood or 5% serum agar media at 30 or 37°C prior to mannan/mannoprotein extraction. Cultivation of the yeast in blood or serum at physiologic temperature resulted in an additive effect on Mw, however, cultivation media had the greatest impact on Mw. Mannan from a yeast grown on blood or serum at 30°C showed a 38.9 and 28.6% increase in Mw, when compared with mannan from YPD-grown yeast at 30°C. Mannan from the yeast pregrown on blood or serum at 37°C showed increased Mw (8.8 and 26.3%) when compared with YPD mannan at 37°C. The changes in Mw over the entire polymer distribution were due to an increase in the amount of mannoprotein (23.8-100%) and a decrease in cell wall mannan (5.7-17.3%). We conclude that C. albicans alters the composition of its cell wall, and thus its phenotype, in response to cultivation in blood, serum and/or physiologic temperature by increasing the amount of the mannoprotein and decreasing the amount of the mannan in the cell wall.     

单体异附加系花药培养创制小麦- 中间偃麦草纯合易位系

利用单体异附加系花药培养细胞工程途径,诱导小麦与中间偃麦草发生染色体易位,通过细胞学分析、荧光原位杂交(F ISH)和SSR鉴定出纯合易位系.研究结果表明,经单体异附加系花药培养创制出1个小麦-中间偃麦草纯合易位系99-803;其花粉母细胞(PM C s)减数分裂中期I染色体构型为18.42个环状二价体 2.57个棒状二价体 0.01个单价体;中间偃麦草的7A i-1染色体与小麦7A或7B染色体发生了非罗伯逊易位,且中间偃麦草易位片段较小;通过该途径获得纯合易位系的频率约为2%.以上结果表明,单体异附加系花药培养是一条向小麦转移异源染色体小片段(基因)的快速高效途径.     

Adenosine triphosphate hydrolysis in rat dental tissues

Summary The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: -glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde.By comparing the enzymatic stainings obtained with the various substrates and at the different pH: s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5-nucleotidase, inorganic pyrophosphatase, 3:5-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.     

Electron microscopic localization of 5''-nucleotidase in the stratum intermedium and ameloblasts

Synopsis 5-nucleotidase was demonstrated at the fine structural level in the stratum intermedium and ameloblasts of the first mandibular molars of CD-1 mice. The enzyme was localized with the Wachstein & Meisel (1957) method along the plasma membranes of the cells of the stratum intermedium and ameloblasts. While 5-nucleotidase was present throughout the stratum intermedium, only the proximal region of the plasma membranes of ameloblasts was demonstrably active for this enzyme. 5-Nucleotidase has been implicated in transport of metabolites across cell membranes, and its localization in the present study supports this implication as well as the transport functions of the stratum intermedium and the stratum intermedium-ameloblastic interface.     

Influence of carbon and nitrogen sources on glutathione catabolic enzymes inCandida albicans during dimorphism

The effect of carbon sources, glucose and sucrose, and nitrogen sources such as ammonia, glutamate andl-citrulline on the activities of glutathione metabolic enzymes has been studied. Yeast and mycelial cells were used to identify changes in activity levels of glutathione reductase (GSSGR), glutathione transferase (GST), glutathione peroxidase (GPX) and -glutamyl transpeptidase (GGT). Enzyme activities from cells grown in sucrose media were lower than in glucose media regardless of the enzyme tested, morphological form, or the growth interval. In all enzymes except GST, activity was higher in yeast form than in mycelia, regardless of nitrogen source, with lower activity from 24 to 72 h than at 96 h. In citrulline media, yeast form showed the maximum GST, GGT, and GPX activity. In ammonia-amended media, mycelia showed maximum activity in GGT, whereas in glutamate media, mycelia showed the maximum activity in GST. Also, the type of nitrogen source had no effect on GPX activity in the mycelial form. Finally, changing the nitrogen source showed no significant effect on GSSGR activity, either in the yeast or mycelial form.     

Inner enamel epithelia synthesize and secrete enamel proteins during mouse molar occlusal "enamel-free area" development

Mesenchyme-derived instructions for odontogenic epithelial differentiation into ameloblasts and the production of enamel matrix has been well established. However, it is not known how position-specific differences within the enamel organ of rodent molar tooth organs regulate the enamel-forming vs. the enamel free areas in the developing cusp. Light microscopy, transmission electron microscopy, and immunocytochemistry using a rabbit anti-mouse amelogenin antibody, were used to map the position-specific patterns within the enamel organ. In the enamel-forming area, ameloblasts were associated with stratum intermedium. In the enamel-free area, another cell type was interposed between inner enamel epithelia (IEE) and stratum intermedium. IEE in the enamel-free area did not have Tomes' processes and secreted enamel matrix not only toward dentin but also between IEE cells. IEE became confluent with stellate reticulum; at this position stratum intermedium cells were no longer detected. The thickness and orientation of dentin matrix collagen fibers in the enamel-free area were different from the fibers in the enamel-forming area. These results suggest that the patterns of epithelial cell-cell and cell-matrix associations during position-specific enamel organ epithelial differentiation may regulate ameloblast matrix synthesis and/or the matrix secretion pathway.     

烟碱降解细菌的分离、鉴定及其降解性能的初步研究

从福建三明地区的土壤中分离得到一株能够高效降解烟碱的菌株 ,编号为DN2。该菌经常规的形态、生理生化分析以及 16SrDNA序列同源性分析 ,鉴定为Ochrobactrumintermedium ,属于α_变形杆细菌纲。该菌在 30℃～4 0℃和pH 6 . 0～ 9. 0范围内具有较高的降解活性 ,其最适值分别为 30℃和 6 5 ,烟碱的耐受浓度在无机盐培养基中可达到 4 0 0 0mg L。该菌能够以烟碱为唯一碳源生长 ,对于 5 0 0mg L烟碱的降解速率为 15mg L·h ,36h烟碱降解率为97. 6 5 %。该菌在烟草工业和环境保护上可能具有应用前景。     

Recombinogenicity and mutagenicity of saccharin in Saccharomyces cerevisiae.

Diploid yeast grown in the presence of a commercial lot of saccharin exhibited reproducible, dose-dependent increases in intergenic and intragenic recombination, and mutation. Cells grew to nearly the same titer in media without saccharin and containing 2 or 20 mg saccharin/ml, although cell viability was somewhat reduced in saccharin-containing media. At the high test dose of 100 mg/ml, titers and cell viability were more markedly lowered. Differences between this study and previous (negative) tests of saccharin in yeast are described.     

Effect of carbon and nitrogen sources on growth and biological efficacy of Pseudomonas fluorescens and Bacillus subtilis against Rhizoctonia solani, the causal agent of bean damping-off

One of the most important environmental factors that regulate the growth and antagonistic efficacy of biocontrol agents is the medium. The aim of this paper was to find the nitrogen and carbon sources that provide maximum biomass production of strains P-5 and P-6 (Pseudomonas fluorescens), B-3 and B-16 (Bacillus subtilis) and minimum cost of media, whilst maintaining biocontrol efficacy. All of the strains were grown in seven liquid media (pH=6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, nutrient broth, molasses and malt extract, at an initial inoculation of 1 x 10(5) CFU ml(-1). Cells from over night cultures used to inoculate soil at 1 x 10(9) CFU cm(-3) soil. At the same time, fungal inoculum (infected millet seed with Rhizoctonia solani) was added to soil at the rate of 2 g kg(-1) soil. Results indicated that growth of P-6, B-3 and B-16 in molasses + yeast extract (1:1 w/w) medium was significantly higher than in the other media. Molasses + yeast extract (1:1 and 2:1 w/w) media supported rapid growth and high cell yields in P-5. In greenhouse condition, results indicated that the influence of the media on the biocontrol efficacy of P-5, P-6, B-3 and B-16 was the same and Pseudomonas fluorescens P-5 in molasses and malt extract media reduced the severity of disease up to 72.8 percent. On the other hand, there were observed significant differences on bean growth after one month in greenhouse. P-5 in molasses + yeast extract (1:1 w/w) medium had the most effects on bean growth promotion. In this study molasses media showed good yield efficacy in all of the strains. The high sucrose concentration in molasses justifies the high biomass in all of the strains. Also, the low cost of molasses allows its concentration to be increased in media. On the other hand, yeast extract was the best organic nitrogen source for antagonist bacteria but it is expensive for an industrial process. So it should be replaced by another industrial product instead of yeast extract, which confirm by an economic and technological study. The results obtained in this study could be used to provide a reliable basis to increase the population of biocontrol agents in fermentation process.