β-Galactosidase of the Extreme Thermophilic Anaerobic Bacterium Thermoanaerobium sp. 2905 and Its Immobilization

The composition of a nutrition medium for cultivating the extreme thermophilic anaerobe Thermoanaerobium sp. 2905 was optimized, which enabled the bacterial -galactosidase production to be substantially enhanced. Xylan and ammonium phosphate were selected as optimal carbon and nitrogen sources, respectively. The enzyme was purified fivefold by precipitation of the aqueous cell extract with alcohol (1 : 1, v/v), and a crude preparation with a specific activity of 46 U per mg protein was obtained. Cells of the extreme thermophile were entrapped in natural or synthetic latex.     

Architecture of Clonal Plants and Morphological Responses to Habitat Heterogeneity

The phalanx and querilla are two extreme architectures. There should be a continuum of interim architecture between phalanx and querilla. The author gives an index describing the continuum v=ln /Inn( ≤v≤1), and discusses the response of spacer length to habitat patchy quality.     

Mercury contamination in Lake Xolotlán (Managua)

Total mercury was measured in different compartments of Lake Xolotlán's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 g Hg.g^–1±0.46 at the surface, with extreme values of 0.16 and 1.8 g.g^–1. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 g.Hg^–1 in January and 506 g.g^–1 in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 g.g^–1±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 g.g^–1±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 g.g^–1±1.29 inC. managuense and 0.62 g.g^–1±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 g.g^–1±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 g.g^–1±6.34 (n=58), and in women 3.39 g.g^–1±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 g.g^–1±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.     

Characterization of Salicola sp. IC10, a lipase- and protease-producing extreme halophile

In order to explore the diversity of extreme halophiles able to produce different hydrolytic enzymes (amylase, protease, lipase and DNAse) in hypersaline habitats of South Spain, a screening program was performed. A total of 43 extreme halophiles showing hydrolytic activities have been isolated and characterized. The isolated strains were able to grow optimally in media with 15–20% (w/v) total salts and in most cases, growth was detected up to 30% (w/v) total salts. Most hydrolase producers were assigned to the family Halobacteriaceae , belonging to the genera Halorubrum (22 strains), Haloarcula (nine strains) and Halobacterium (nine strains), and three isolates were characterized as extremely halophilic bacteria (genera Salicola, Salinibacter and Pseudomonas ). An extremely halophilic isolate, strain IC10, showing lipase and protease activities and identified as a Salicola strain of potential biotechnological interest, was further studied. The optimum growth conditions for this strain were 15–20% (w/v) NaCl, pH 8.0, and 37 °C. Zymographic analysis of strain IC10 detected the lipolytic activity in the intracellular fraction, showing the highest activity against p -nitrophenyl-butyrate as a substrate in a colorimetric assay, whereas the proteolytic activity was detected in the extracellular fraction. This protease degraded casein, gelatin, bovine serum albumin and egg albumin.     

Outdoor and indoor cultivation of Spirulina platensis in the extreme south of Brazil

Water supplemented with 10% or 20% (v/v) of Zarrouk medium was used to cultivate Spirulina platensis in closed and open bioreactors under controlled conditions (30 degrees C, 32.5 micromol m(-2) s(-1), 12 h light/dark photoperiod) and in a greenhouse (9.4 to 46 degrees C, up to 2800 micromol m(-2) s(-1), variable day length photoperiod) using different initial biomass concentrations (X0) in the extreme south of Brazil (32.05 degrees S, 52.11 degrees W). Under controlled conditions the maximum specific growth rate (micromax) was 0.102 d(-1), the biomass doubling time (t(d)) was 6.8 d, the maximum dry biomass concentration (Xmax) was 1.94 g L(-1) and the maximum productivity (Pmax) was 0.059 g L(-)1 d(-1), while the corresponding values in the greenhouse experiments were micromax = 0.322 d(-1), t(d) = 2.2 d, Xmax = 1.73 g L(-1) and Pmax = 0.112 g L(-1) d(-1). Under controlled conditions the highest values for these parameters occurred when X0 = 0.15 g L(-1), while in the greenhouse X0 = 0.4 g L(-1) produced the highest values. These results show that the cultivation of S. platensis in greenhouses in the extreme south of Brazil is technically viable and that the S. platensis inoculum and the concentration of Zarrouk medium can be combined in such a way as to obtain growth and productivity parameters comparable, or superior, to those occurring in bioreactors under controlled conditions of temperature, illuminance and photoperiod.     

嗜盐碱性淀粉酶产生条件和性质的初步研究

从我国内蒙古自治区察汗淖碱湖分离到一株能产胞外嗜盐碱性淀粉酶的极端嗜盐嗜碱杆菌(Natronobacterium sp.)C-212,该菌产酶的最适pH和NaCl浓度分别为9.5和20%,最适碳源为可溶性淀粉,氮源为复合蛋白胨.酶反应最适温度为50℃,pH为8.5,NaCl浓度为2.6mol/L,该酶在pH9.5最稳定,NaCl可增加酶的热稳定性,酶降解可溶性淀粉的主要产物为葡萄糖、麦芽糖、麦芽三糖及其他寡糖.     

Biotransformation of octane by E. coli HB101[pGEc47] on defined medium: octanoate production and product inhibition

E. coli HB101[pGEc47], which is able to convert octane to octanoate, but cannot oxidize octanoate further, was grown on defined medium with glucose as carbon source in batch and continuous culture. The biomass yield on glucose decreased from 0.32 +/- 0.02 g g-1 in aqueous cultivations to 0.25 +/- 0.02 g g-1 in the presence of octane. Maximal octanoate productivities of 0.6 g L-1 h-1 were the same as found in cultivations on complex medium. The glucose-based carbon recovery in these experiments was 99 +/- 4% (in extreme, between 90% and 105%). An increase of the octane feed from 1% to 2% (v/v) or more led to washout of cells. This effect was reversible when the octane feed was decreased to its initial value of 1%. Analysis of experimental data by model simulation strongly suggested that washout was due to inhibition by octanoate only. Pulses of octanoate to a continuous culture grown on aqueous media were applied to analyze the inhibition further. Inhibition by acetate was not significant, but its presence in the medium reflected a physiological state that made the cells more sensitive to octanoate inhibition. Model simulation with linear inhibition kinetics could perfectly predict glucose consumption and the resulting glucose concentration. The linear type of inhibition was confirmed by a variety of batch experiments in the presence of different concentrations of octanoate. The glucose-based specific growth rate, mu, decreased linearly with increasing concentrations of octanoate and became zero at a threshold concentration pmax of 5.25 +/- 0.25 g L-1.     

Metagenomic Assessment of Prokaryotic Diversity within Hypersaline Tuz Lake,Turkey

Microbiology - Tuz Lake is the second biggest lake with an extreme hypersaline environment (over 32% (w/v) salt) in Turkey. It is reported that the lake was of marine origin, and its formation...     

Effects of oxygen on aerobic solid-state biodegradation kinetics

Oxygen is a critical control variable for composting and other solid-state biodegradation processes. In this study we examined the effect of varying oxygen concentrations (1%, 4%, and 21% O2 (v/v)) on biodegradation kinetics under different substrate (sewage sludge and synthetic food waste), temperature (35, 45, 55, and 65 degrees C), and moisture (36-60% H2O) conditions. Three forms of a saturation or Monod-type model and one form of an exponential model were evaluated against data from extensive experiments under carefully controlled environmental conditions. The exponential model performed well at temperatures from 35 to 55 degrees C but had problems at higher temperatures. The Monod-type models yielded the best fit based on R2 values. Multiple linear regression was used to express the oxygen half-saturation coefficient as a function of temperature and moisture. For a modified one-parameter saturation model the half-saturation coefficient varied from -0.67% to 1.74% v/v O2 under the range of conditions typical of composting systems. While the positive correlation of biodegradation rate with oxygen concentration reported by previous researchers held true for temperatures below 55 degrees C, an inverse relationship was found at 65 degrees C. Although this study did not directly examine anaerobic conditions, the results under microaerophilic conditions suggest oxygen may not offer kinetic advantages for extreme thermophilic biodegradation processes.     

Pyruvate carboxylase from Aspergillus nidulans. Effects of regulatory modifiers on the structure of the enzyme

Pigment-binding protein of the facultatively phototrophic bacterium Rhodospeudomonas capsulata could be selectively synthesized in toluene-treated cells as well as in homologous and heterologous cell-free translation systems by isolated polysomes. It is shown that the pigment-binding polypeptides of the light-harvesting complexes are encoded by messenger RNA of extreme longevity. The dependence of their synthesis on the concomitant synthesis of tetrapyrroles was demonstrated in the toluene-treated cells. The large Mr-28 000 polypeptide of the reaction center and the Mr-10 000 pigment-binding polypeptide of the light-harvesting complex II were found to be synthesized by free (water-soluble) polysomes without a cleavable 'leader' or 'signal' peptide [reviewed by W. Wickner (1979) Annu. Rev. Biochem. 48, 23-45]. The Mr-10 000 polypeptide, as synthesized in vitro, was studied in more detail. Unlike the membrane-assembled polypeptide in vivo it was insoluble in an organic solvent mixture (chloroform/methanol 1:1, v/v). After detergent denaturation in the presence of membrane isolated from the organism it became organic-solvent-soluble. Obviously the polypeptide could be induced to assume alternative conformations in which its apolar residues were either exposed to the solvent or buried within. These findings, in agreement with Wickner's hypothesis, indicate that the Mr-10 000 polypeptide may enter the lipid bilayer by a 'membrane-triggered' conformational change.     

Physiological behaviour of Saccharomyces cerevisiae in aerated fed-batch fermentation for high level production of bioethanol

Saccharomyces cerevisiae was able to produce 20% (v/v) of ethanol in 45 h in a fully aerated fed-batch process recently developed in our laboratory. A notable feature of this process was a production phase uncoupled to growth, the extent of which was critical for high-level ethanol production. As the level of production was found to be highly variable, we investigated on this high variability by means of a detailed physiological analysis of yeast cells in two fed-batch fermentations showing the most extreme behaviour. We found a massive leakage of intracellular metabolites into the growth medium which correlated with the drop of cell viability. The loss of viability was also found to be proportional to the reduction of plasma membrane phospholipids. Finally, the fed-batch processes with the longest uncoupling phase were characterized by induction of storage carbohydrates at the onset of this phase, whereas this metabolic event was not seen in processes with a short uncoupling phase. Taken together, our results suggested that reproducible high-level bioethanol production in aerated fed-batch processes may be linked to the ability of yeast cells to impede ethanol toxicity by triggering a metabolic remodelling reminiscent to that of cells entering a quiescent GO/G1 state.     

Genetic and immunological analysis of a novel variant of Shiga toxin 1 from bovine Escherichia coli strains and development of bead-ELISA to detect the variant toxin

A novel variant of Shiga toxin 1 (Stx1) was identified from bovine Escherichia coli strains. The stx1 variant genes designated as stx1v51 and stx1v52 were cloned and sequenced. The two variant genes differed each other by 2 bp, but the deduced amino acid sequences of the two Stx1 variant toxins were the same and had 94% and 92% homology to that of prototype A and B subunits of Stx1, respectively. The variant toxin designated as Stx1v52 was purified to homogeneity. Although inhibition of protein synthesis in vitro by purified Stx1v52 was almost equal to that of purified Stx1, Vero cell cytotoxicity and mouse lethality of Stx1v52 were several folds lower than those of prototype Stx1. In Ouchterlony double gel diffusion test, the precipitin line between Stx1v52 and Stx1 formed a spur against anti-Stx1 serum but was fused against anti-Stx1v52 serum. Stx1v52 and Stx1v52-specific-bead-ELISA was developed, and both Stx1 and Stx1v52 could be detected with high sensitivity using Stx1v52 conjugate. However, Stx1v52 but not Stx1 could be detected with Stx1v52-specific bead-ELISA.     

Alkali-thermostable and cellulase-free xylanase production by an extreme thermophile <Emphasis Type="Italic">Geobacillus thermoleovorans</Emphasis>

The optimization of cultural variables resulted in a marked enhancement in the secretion of cellulase-free and alkali-thermostable xylanase (EC 3.2.1.8) by an extreme thermophile Geobacillus thermoleovorans. The enzyme secretion was enhanced when the medium was supplemented with xylan (0.15%) and Tween-80 (0.1% v/v). In wheat bran-tryptone medium, the peak in enzyme production was attained within 42 h in a fermenter as compared to 72 h in shake flasks. Optimization of the culture conditions resulted in a 7.72-fold enhancement in enzyme production. The cellulase-free xylanase was optimally active at pH 8.5 and 80°C, and it was found to be useful in the pre-bleaching process of paper pulps.     

延安市安塞区极端降水变化特征

以1980—2019年安塞气象站的日降水资料为基础选取11个极端降水指标,从降水强度和降水频率的角度对安塞区的极端降水数据进行分析,并对未来极端降水趋势进行预测。结果表明: 1980—2019年,安塞区极端降水指标总体呈现下降趋势,其中,大雨以上日数和普通日降水强度的下降趋势达到显著水平,其气候倾向斜率分别为-0.65 d·(10 a)^-1和-0.32 mm·d^-1·(10 a)^-1。除持续湿润日数和极端降水总量外,其余极端降水指标均存在突变点,突变之后各指标多呈下降趋势,且年降水量、中雨以上日数、大雨以上日数、暴雨以上日数、异常降水总量、普通日降水强度的下降趋势达到显著水平。持续干燥日数与其他指标的相关性较低且与一些指标呈负相关,而持续湿润日数只与少数几个指标具有相关性,此外,其他极端降水指标之间均呈显著相关。Hurst指数分析表明,未来安塞区极端降水总体变化趋势具有持续性。     

Cuticular lipids and desiccation resistance in overwintering larvae of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae)

Within their gall, larvae of the goldenrod gall fly (Eurosta solidaginis) experience severe desiccating conditions as well as highly variable thermal conditions and extreme cold during winter. Through the autumn and early winter, field-collected larvae acquired markedly enhanced resistance to desiccation and freezing. At the same time, they increased their cuticular surface hydrocarbons. Hydrocarbons were the major lipid class extracted by hexane or chloroform from the cuticular surface of overwintering gall fly larvae. The major hydrocarbon classes were the 2-methylalkanes which consisted mainly of 2-methyltriacontane. 2-Methyltriacontane comprised 48-68% of the total hydrocarbons during the larval stages. Total hydrocarbons increased from 122 ng/larva in early third instar larvae collected in September to 4900 ng/larva in those collected in January. Although washing of the cuticular surface with chloroform or chloroform:methanol (2:1, v:v) caused marked increases in rates of water loss, treatment with hexane and methanol had little effect on water loss rates.     

Growth Tolerance of Rhizobia Isolated from Sand Dune Legumes of the Southwest Coast of India

This paper describes the properties of rhizobia from extreme soil environments which are characterized by high temperatures, salt concentrations and also rather extreme pH values due to the contamination by spray water from the sea. Coastal sand dunes are such extreme habitats which support a variety of microorganisms. To explore stress‐tolerant rhizobia, ten rhizobial strains were isolated from five wild legumes from two dune systems of the southwest coast of India. They were tested for growth performance or tolerance at a wide range of temperatures (30–55 °C), salinity (0.1–4.5 % w/v) and initial pH values (3.5–11). Growth of five isolates was highest between 30–40 °C, while four isolates showed considerable growth up to 2.5 % salinity (at 35 °C). All isolates demonstrated elevated growth at an initial pH of between 5–6 (at 35 °C and 2 % salinity), while five isolates had additional growth peaks at an initial pH of between pH 7.5–9 indicating alkaline tolerance and were suitable for efficient phosphate solubilization. The stress tolerance traits of these rhizobia are of potential value for strain improvement in agriculture or the bioremediation of soils at elevated temperatures, salinity and extreme pH values, and thus are of high biotechnological importance.     

新疆泥火山产酶嗜盐放线菌的筛选及多样性

[目的]了解新疆乌苏泥火山嗜盐放线菌及其产酶功能多样性.[方法]分别采用含有5%与10%NaCl的5种分离培养基,稀释平板涂布法对泥火山土壤样品进行分离;利用五种筛选培养基定性检测酶活性;在形态特征、耐盐性实验及16S rDNA基因测序的基础上进行系统发育学分析.[结果]获得嗜盐放线菌43株,极端嗜盐放线菌3株.4株嗜盐放线菌产脂肪酶,30株产半乳糖苷酶,27株产淀粉酶,6株产酯酶,4株产纤维素酶,1株同时产4种酶.系统发育学分析结果表明其中24株为拟诺卡氏菌属(Nocardiopsis),1株为链霉菌属(Streptomyces).产两种酶的菌株10006与Nocardiopsis exhalans(AY03600)相似性为96.64%(小于97%),可能是潜在的新种.[结论]本研究表明新疆乌苏泥火山中存在大量的产半乳糖苷酶及淀粉酶的嗜盐放线菌,所分离到的拟诺卡氏菌属产酶多样性比较高,并且潜藏着新的微生物资源.     

Ultrastructure ofDebaryomyces hansenii

Summary The ultrastructure of the extreme halotolerant yeastDebaryomyces hansenii (Zopf) van Rij was similar whether the organism was grown under normal physiological conditions or at high concentrations of NaCl (12, 20 per cent w/v). A multitude of channels often seen in association with plasma membrane and/or vacuoles occur in the cytoplasm. The vacuoles contain lipid storage material. A decrease in mitochondrial size was observed with increasing salt concentration. The ultrastructure has been discussed with respect to halotolerance.     

Nitrogen fixation associated withEichhornia crassipes

Summary Azotobacter associated withEichhornia crassipes were found to be concentrated in the slime formed around petiole bases. Massive colonies formed where raw slime was applied to nitrogen-free medium inoculated with Azotobacter. Slime in which Azotobacter had been killed did not stimulate the formation of massive colonies unless live Azotobacter cells were mixed into it. Acetylene reduction tests indicated that Azotobacter associated with Eichhornia did not fix nitrogen unless the plant was suffering extreme nitrogen deficiency, and that the maximum rate of fixation was inadequate for rapid plant growth.