粘细菌CS211的分离纯化、生物学特征及其抗生活性初步研究

从采白成都市郊森林的土壤中分离纯化到二株粘细菌CS262和CS211。二株粘细菌在琼脂平板上表现出相互抑制子实体发育的拮抗作用。CS211菌株对蜡状芽孢杆菌,藤黄八叠球菌,枯草芽孢杆菌,金黄色葡萄球菌具有很强的抑制作用。采用非极性大孔树脂吸附和TIC方法对抗菌活性物质作了初步研究。     

Optional production and utilization of polysaccharide by Aeromonas hydrophila

Glucans from the fish pathogen Aeromonas hydrophila have been extracted andpurified by a method utilizing phenol/water followed by sodium deoxycholate rather than the traditional sodium hydroxide extraction. Presence of substantial amounts of these glucans was shown to be dependant on whether or not the substrate contained dextrose, a point which had import because of the low carbohydrate environment in which this species must survive and multiply. These glucans, produced in the log phase, were utilized during the later growth period.The structures of the two purified glucans were examined by methylation analysis, periodate oxidation, and enzymatic degradation. The results indicated that A. hydrophila under low-carbohydrate growth conditions produced two similar but distinguishable 14 linked glucans substituted 16 by single monosaccharide residues or short chains to give an amylopectinglycogen type of polysaccharide.     

Short-term changes in polysaccharide utilization mechanisms of marine bacterioplankton during a spring phytoplankton bloom

Spring phytoplankton blooms in temperate environments contribute disproportionately to global marine productivity. Bloom-derived organic matter, much of it occurring as polysaccharides, fuels biogeochemical cycles driven by interacting autotrophic and heterotrophic communities. We tracked changes in the mode of polysaccharide utilization by heterotrophic bacteria during the course of a diatom-dominated bloom in the German Bight, North Sea. Polysaccharides can be taken up in a ‘selfish’ mode, where initial hydrolysis is coupled to transport into the periplasm, such that little to no low-molecular weight (LMW) products are externally released to the environment. Alternatively, polysaccharides hydrolyzed by cell-surface attached or free extracellular enzymes (external hydrolysis) yield LMW products available to the wider bacterioplankton community. In the early bloom phase, selfish activity was accompanied by low extracellular hydrolysis rates of a few polysaccharides. As the bloom progressed, selfish uptake increased markedly, and external hydrolysis rates increased, but only for a limited range of substrates. The late bloom phase was characterized by high external hydrolysis rates of a broad range of polysaccharides and reduced selfish uptake of polysaccharides, except for laminarin. Substrate utilization mode is related both to substrate structural complexity and to the bloom-stage dependent composition of the heterotrophic bacterial community.     

Conformational transition and polyelectrolyte behaviour of a succinoglycan polysaccharide

We report the chemical characterization and the relationship between the physicochemical properties and conformational change of a succinoglycan polysaccharide produced by Pseudomonas sp, NCIB 11592. The expected chemical structure is confirmed, with a ratio of D-glucose: D-galactose: pyruvate: succinate of 7:1:1:1. The molecular weight of the native form is 4.2 x 10(6) but after a single heating cycle through the disordered state the molecular weight is reduced to 3.0 x 10(6). The polymer has a polymolecularity index of 1.3 in both cases. The conformational change was studied by different methods which enabled us to define the exact nature of the ordered and disordered states. The conformational transition depends on the temperature, the ionic strength and the nature of the counterion. The polyelectrolyte behaviour is in favour of a single chain conformation with an intramolecular helix-coil transition. The enthalpy change during this transition is greater than that expected solely on the basis of the polyelectrolyte contribution. It may be associated with changes in solvation or a rearrangement of water molecules in close association with the polymer.     

Accumulation of an iodophilic polysaccharide during growth of Acetivibrio cellulolyticus on cellobiose

Maximum growth of Acetivibrio cellulolyticus in 1% cellobiose (w/v, added as filter sterilized solution) medium was observed after about 24h of incubation at 35°C. The metabolic end products of growth were H₂, CO₂, acetic acid, ethanol and glucose. Growth was adversely affected if cellobiose was autoclaved with the rest of the media ingredients. In the presence of an excess of cellobiose, the cells accumulated large quantities of an iodophilic polysaccharide (IPS). The maximum IPS accumulation (about 37% of the cell dry weight) was observed after about 12h growth under nitrogen-limiting conditions. Starvation of these cells anaerobically, in a pH 7.0 phosphate buffer for 10 h at 35°C, resulted in about 50% drop in the IPS. The results also indicated that A. cellulolyticus accumulated this iodophilic polysaccharide during growth on cellobiose but not during cultivation on cellulose.Abbreviation IPS iodophilic polysaccharide Issued as NRCC No. 19386     

Cruentaren A, a highly cytotoxic benzolactone from Myxobacteria is a novel selective inhibitor of mitochondrial F1-ATPases

Cruentaren A, a new antifungal benzolactone produced by the myxobacterium Byssovorax cruenta, proved to be highly cytotoxic against various human cell lines. It inhibited the proliferation of different cancer cell lines including a multidrug-resistant KB line at low nanomolar levels. It arrested human histocytic lymphoma cells (U-937) in G(0/1) phase, but did not trigger an apoptotic process. Studies to uncover the molecular target of cruentaren A showed that the novel compound, despite its structural similarity to the benzolactone enamides apicularen and salicylihalamide, was no V-ATPase inhibitor. In contrast, cruentaren specifically inhibited mitochondrial F(O)F(1)-ATPases with IC50 values of 15-30 nM. Although the exact binding site of cruentaren remains undefined, inhibition was shown to occur by interaction with the catalytic F(1) domain. Since mitochondrial ATPases play a crucial role in the pathophysiology of several human disorders including cancer, cruentaren or synthetic derivatives thereof could form the basis of future therapeutic strategies.     

盘针孢菌发酵及其胞外多糖抗氧化活性

[目的]研究盘针孢菌的发酵条件及其胞外多糖(EPS)抗氧化活性.[方法]分别研究碳源、氮源、生长因子、pH值和培养时间等条件对盘针孢菌多糖产量的影响作用,并通过测定其多糖的还原能力及对羟自由基(·OH)和1,1-二苯基苦基苯肼(DPPH)自由基的清除作用研究该多糖的抗氧化活性.[结果]盘针孢菌多糖发酵的最佳条件为20%的马铃薯浸汁,20g/L麦芽糖,5 g/L(NH4)2SO4,0.01 g/L L-胱氨酸,pH 5.0,25℃下培养10 d.在此条件下,多糖产量达到37.52 mg/L,与在基础发酵培养基条件下相比,其多糖产量提高了84.10%.盘针孢菌多糖对·OH和DPPH自由基均有较好的清除作用,在多糖浓度为50 mg/L时,对·OH的清除率达到50.81%;多糖浓度为20 mg/L时,对DPPH自由基的清除率达到14.21%.[结论]发酵条件对盘针孢菌多糖代谢具有重要的调控作用,且该多糖具有明显的抗氧化活性.     

The ATP level in the thermophilic cyanobacterium Synechococcus 6716 during light-dark transition and in the presence of some specific inhibitors

Abstract ATP concentrations in whole cells of Synechococcus 6716 are measured with the luciferin-luciferase method. Under aerobic conditions the ATP level in the dark is 70% of the level in the light; under anaerobic conditions this is 20%. The controversial time-dependent changes of the ATP content as reported in earlier studies are discussed in relation to the used ATP determinations. The electron transfer inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and Antimycin A have no effect on the ATP level neither in the light, nor in the dark. KCN only affects the ATP level in the dark under aerobic conditions. The energy transfer inhibitors N , N '-dicyclohexylcarbodiimide (DCCD) and Venturicidin are effective both in the light and in the dark, be it for about 50%.     

Transitional steady-state investigations during aerobic-anaerobic transition of glucose utilization by Escherichia coli K-12.

Transitional steady-state investigations during changes in oxygen tension under aerobic and during aerobic-anaerobic transition conditions were carried out with the aim of finding an indicator system which separates the equilibrium from the non-equilibrium state. Of the parameters used i.e. biomass formation, CO2 production, Q02, NADH oxidase, succinate dehydrogenase, phosphofructokinase, glyceraldehyde-3 phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and 2-oxoglutarate dehydrogenase, only the three enzymes requiring NADH or NADP for their function fulfilled the requirements. Biomass production and CO2 formation were useful only during the aerobic-anaerobic transition period. In each case the response was immediate and the indicator systems demonstrated that a new steady state of oxygen was always obtained after 11 h which, at the specific growth rate used, was equivalent to at least two volume replacements of the growth vessel.     

Clocks and patterns in myxobacteria: a remembrance of Art Winfree

At the beginning of their aggregation phase waves of cell density sweep across the surface of myxobacteria colonies. These waves are unlike any other in biology. Waves can be linear, concentric or spiral and when they collide, instead of annihilating one another they appear to pass through each other unchanged. Moreover, the wavelength determines the spacing and pattern of fruiting bodies that will rise up presaging sporulation. The explanation for these waves was suggested by the work of Art Winfree on cellular clocks, and confirmed by a mathematical model that explains all of the observed wave behavior. The story of how this model evolved illustrates the roles of chance and scientific networking in the search for the explanation of a new phenomenon.     

Anti-fatigue activity of a Lachnum polysaccharide and its carboxymethylated derivative in mice

The present study was designed to evaluate the anti-fatigue activity of an exopolysaccharide LEP-1b and its carboxymethylated derivative CLEP-1b from a Lachnum sp. Carboxymethylation was confirmed through FT-IR and ¹³C NMR spectroscopies, which showed that the (–CH₂COOH) group was attached to an oxygen (O) atom of the hydroxyl group on (C-3) of LEP-1b. Each treatment group LEP-1b and CLEP-1b at doses (50, 100, 200 mg/kg, respectively) ameliorated physical fatigue and extended exhaustive swimming time in mice. Results of the fatigue related biochemical markers showed that LEP-1b and CLEP-1b at doses (50, 100, 200 mg/kg, respectively) increased the content of hepatic glycogen and decreased the level of serum urea nitrogen and lactic acid. Additionally, LEP-1b and CLEP-1b enhanced the antioxidant enzymes’ activities and reduced the lipid peroxidation. Moreover, results revealed that CLEP-1b had higher anti-fatigue activity than LEP-1b at same doses but without statistical significance, especially CLEP-1b (200 mg/kg) had strong anti-fatigue effects. Therefore, LEP-1b and CLEP-1b can potentially be exploited as a kind of healthcare compound to combat fatigue and to boost physical strength.     

Strip counts as a means of determining densities and habitat utilization patterns in lake fishes

Synopsis The strip count method of determining fish densities was investigated for a small lake in a series of inshore sites that differed in their physical and biological characteristics and in the communities of fishes present. Overall total numbers of fish, number of species, ratio of commonest to total species, and 2nd commonest to total species, were investigated. Counts were made during time of the feeding peaks.Repeatability of the method was tested by series of five traverses at 10-minute intervals and was good both for total numbers of fish and ratio of commonest species to total fish. However, it varied with the habitat type, being excellent for small semi-isolated weedy sites, good for gravel-bottom sites, but only fair in open sandy bays where the strip was laid in the middle of an extensive area of homogeneous habitat.Series of comparative counts made (a) between morning and afternoon on the same day and, (b) between successive mornings, to determine how constant populations were between these time intervals, proved to be within the same general range but were significantly different by the Mann Whitney U test at the = 0.05 level.In small lakes the strip count method proves to have considerable potential in the study of habitat specializations, taxocene structures, and relative abundances.     

Fate of nitrate during initial nitrate utilization by nitrogen-depleted dwarf bean

The fate of nitrate and nitrogen-15 was followed during the apparent induction phase (6h) for nitrate uptake by N-depleted dwarf bean (Phaseolus vulgaris L. ev. Witte Krombek). Experiments were done with intact plants and with detached root systems. Qualitatively and quantitatively, xylem exudation from detached roots was a bad estimate of the export of NO^?₃ or NO^?₃-¹⁵N from roots of intact plants. In vivo nitrate reductase activity (NRA) agreed well with in situ reduction, calculated as the difference between uptake and accumulation in whole plants, provided NRA was assayed with merely endogenous nitrate as substrate (‘actual’ NRA). The majority (75%) of the entering nitrate remained unmetabolized. Both nitrate reduction and nitrate accumulation occurred predominantly in the root system. Some (< 25%) of the root-reduced nitrate-N was translocated to the shoot. Nitrate uptake occurred against the concentration gradient between medium and root cells, and probably against the gradient of the electro-chemical potential of nitrate. Part of the energy expended for NO^?₃ absorption came from the tops, since decapitation and ringing at the stem base restricted nitrate uptake.     

Accumulation of poly-beta-hydroxybutyrate in Nostoc muscorum: regulation by pH, light-dark cycles, N and P status and carbon sources

Accumulation of poly-beta-hydroxybutyrate (PHB) in Nostoc muscorum was studied. Cells harvested at stationary phase of growth depicted maximum accumulation i.e. 8.6% (w/w) of dry cells as compared to lag (4.1%) or logarithmic (6.1%) phases of cultures. In contrast to alkaline pH, acidic pH, continuous illumination and cells grown in presence of combined nitrogen sources, such as NH(4)Cl and KNO(3), were found to affect PHB accumulation negatively. However, P-deficiency and addition of exogenous carbon sources (acetate, glucose, maltose, fructose and ethanol) were found stimulatory for PHB accumulation. In this report PHB accumulation in N. muscorum was boosted up to 35% (w/w) of dry cells when cells supplemented with 0.2% acetate were subjected to dark incubation for 7 days. Further studies are needed at metabolic engineering level or to apply genetic engineering techniques to improve the expression level of PHB photoproduction in cyanobacteria.     

Different light-dark cycles affect growth rate and food intake of mice

The adaptation of the endogenous rhythm of an organism to external cycles may influence the development of physiological processes in animals. Light not only synchronizes the circadian system, but also exerts profound direct effects: the immediate reduction of melatonin release at night-time and the inhibition of locomotor activity in nocturnal rodents after a light pulse are well-known examples, yet little is known about effects of different light/dark (LD) cycles on the level of corticosterone, growth hormone and growth rate. Mice were raised under different period length of LD cycle including LD5:5 (light: 5 h; dark: 5 h), LD12:12 (light: 12 h; dark: 12 h) and LD16:16 (light: 16 h; dark: 16 h) for four weeks. Mice in LD5:5 and LD16:16 groups manifested higher locomotor activity, plasma corticosterone and growth hormone concentrations and growth rate than the LD12:12 group. The results suggest that different LD cycles may affect many physiological processes including growth rate, food intake and hormones, and the change of growth rate in different LD cycles may be related to the level of corticosterone and growth hormone concentrations. The results also suggest that both the long-period LD cycle and short-period LD cycles can improve the growth of mice, but they disturbed the biorhythm stabilization and affected hormone secretion; in general, these conditions would not promote the animals' survival.     

Bacteriostatic activity of human lactoferrin against Staphylococcus aureus is a function of its iron-binding properties and is not influenced by antibiotic resistance

The in vitro antistaphylococcal activity of lactoferrin and the antibiotic resistance of clinical Staphylococcus aureus isolates obtained from three different sites of infection were examined. Antibiotic, but not lactoferrin resistance correlated with selective antibiotic pressure, and nosocomial and most community isolates were antibiotic resistant, whereas only a third of each group was resistant to lactoferrin. The antimicrobial activity of lactoferrin, both in defined medium and in normal human plasma serum, was dependent upon its ferrochelating properties. Therapeutic approaches based on the use of ferrochelating agents such as lactoferrin combined with antimicrobial drugs may help to counteract the reduced efficacy of current antibiotics.     

芽胞杆菌抗菌活性和纤维素酶活性的测定

目的筛选鸡用益生菌。方法通过牛津杯法、混菌法和DNS分光光度法对从鸡肠道分离的10株芽胞杆菌进行抑菌效果及纤维素酶活性测定。结果编号为Y1、Y5、Y7的3株芽胞杆菌对测试菌具有较好抑菌效果,编号为Y2、Y4、Y5的3株芽胞杆菌具有较高的产酶活性。结论从分离的10株芽胞杆菌中筛选出1株（编号为Y5）兼具较好抑菌效果和较高产酶活性的地衣芽胞杆菌,具有作为饲用益生菌开发的潜能。     

一株海藻多糖降解菌的分离与鉴定

【目的】从腐烂的褐藻中筛选一株海藻多糖降解菌,编号L206,分析其对不同多糖的降解能力。【方法】通过形态观察、生化单因子试验及16S r RNA基因鉴定细菌,DNS法测定海藻多糖降解酶活性等。【结果】海洋细菌L206,革兰氏阴性短杆菌,生长对数期为3-21 h,适宜生长的Na Cl质量浓度为0-3%(质量体积比);通过16S r RNA基因鉴定为白色噬琼胶菌(Agarivorans albus);L206被海带粉诱导至72 h时,综合复合酶活力达到最大,其中淀粉酶活力最高(28.17 U/m L),木聚糖酶次之(23.83 U/m L)。【结论】白色噬琼胶菌L206是一株多能型多糖降解菌,对褐藻多糖有特殊的降解能力,具有潜在开发价值。     

In vitro leishmanicidal activity of a monoclonal antibody mimicking a yeast killer toxin

The microbicidal effect of a monoclonal antiidiotypic antibody, mimicking the activity of a yeast killer toxin, characterized by a wide antimicrobial spectrum, has been evaluated in vitro against two relevant species of protozoan parasites, Leishmania major and Leishmania infantum. The antiidiotypic antibody exerted a significant and dose-dependent antileishmanial activity against parasite promastigotes in comparison to an irrelevant isotype-matched monoclonal antibody. This is the first demonstration that an antibody, which had been already shown to be fungicidal and bactericidal, may also exert a direct microbicidal activity against protozoa.     

Gel formation and low-temperature intramolecular conformation transition of a triple-helical polysaccharide lentinan in water

The gelation behavior of the triple-helical polysaccharide lentinan fractions having different molecular weights in water at 25 degrees C were studied by using a rheometer. The analysis of concentration and molecular weight dependence of shear stress and shear viscosity showed that aqueous lentinan is a typical shear-thinning fluid, possessing potential as a viscosity control agent, and that a weak gel with entangled network structure formed. The dynamic oscillatory behavior of lentinan in the temperature range of 1-15 degrees C was also investigated by rheologic method. The storage modulus G' and complex viscosity eta* increased first with decreasing temperature, and underwent a maximum centered at 7-9 degrees C, and then decreased with further decreasing temperature. This abnormal phenomenon was ascribed to formation of rigid structure in the gel state, which was confirmed by the experimental results from micro-DSC. The micro-DSC curves showed that an endothermic peak appeared at 7-9 degrees C for lentinan in water upon heating, which was attributable to the intramolecular order-disorder structure transition similar to triple-helical polysaccharide schizophyllan. Namely, at lower temperature, the side glucose residues of lentinan (triplix II) formed a well-organized triple-helical structure (triplix I) through hydrogen-bonding with the surrounding water molecules. Moreover, this conformation transition was proved to be thermally reversible. (c) 2008 Wiley Periodicals, Inc. Biopolymers 89: 852-861, 2008.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.