Effect of continuous Cd feeding on the performance of a nitrification reactor

The inhibitory effect of Cd on nitrification was investigated in a continuous-flow system with enriched nitrifying bacteria. The maximum specific ammonium utilization rate and the half-saturation constant were found as 671 mg NH₄–N/g VSS day and 0.48 mg/l, respectively. In the case of continuous Cd input at 1 and 2.5 mg/l, nitrification was inhibited by 30% and 47%, respectively. Inhibition ranged from 20% to 40% and no further increase in inhibition was exhibited in new runs except at 10 mg/l influent Cd. At 10 mg/l influent Cd, specific ammonium utilization and nitrate production rates were inhibited by 90%. On the contrary, a serious nitrite accumulation was not observed during this period. When Cd feeding was stopped, recovery from inhibition was observed after 37 day which was seen by the improvement in ammonium utilization and nitrate production rates. A shift in microbial population from the initial Nitrosomonas sp. to the Cd-tolerant Nitrosospira sp. was observed in the recovery period from severe Cd inhibition. After the domination of Nitrosospira species, redosing at 10 mg/l and then at 15 mg/l did not affect the performance as before.     

Taxonomic studies on three marine pleurostomatid ciliates, Litonotus bergeri nov. spec., L. blattereri nov. spec. and L. petzi nov. spec. (Ciliophora, Pleurostomatida) from North China Sea

The morphology and infraciliature of three pleurostomatid ciliates, Litonotus bergeri nov. spec., L. blattereri nov. spec. and L. petzi nov. spec., collected from mariculture ponds near Qingdao (Tsingtao), China, were investigated using live observations and the protargol impregnation method. These new species are distinguished from their congeners by a combination of characters including the typical distribution of extrusomes, i.e., along entire ventral margin, the number of macronuclear nodules, features and number of somatic kineties, living morphology, number and position of contractile vacuoles and their marine biotopes. Considering the distribution of extrusomes and general morphology, five new combinations are suggested, Litonotus vermiforme (Sauerbrey, 1928) nov. comb. [basionym: Loxophyllum vermiforme Sauerbrey, 1928], Litonotus levigatum (Sauerbrey, 1928) nov. comb. [basionym: Loxophyllum levigatum Sauerbrey, 1928], Litonotus undulatum (Sauerbrey, 1928) nov. comb. [basionym: Loxophyllum undulatum Sauerbrey, 1928], Loxophyllum pictus (Gruber, 1884) nov. comb. [basionym: Litonotus pictus Gruber, 1884] and Loxophyllum trichocystiferus (Foissner, 1984) nov. comb. [basionym: Litonotus trichocystiferus Foissner, 1984].     

Methanocorpusculaceae fam. nov., represented by Methanocorpusculum parvum,Methanocorpusculum sinense spec. nov. and Methanocorpusculum bavaricum spec. nov.

Two new methanogenic bacteria, Methanocorpusculum sinense spec. nov. strain DSM 4274 from a pilot plant for treatment of distillery wastewater in Chengdu (Province Sichuan, China), and Methanocorpusculum bavaricum spec. nov. strain DSM 4179, from a wastewater pond of the sugar factory in Regensburg (Bavaria, FRG) are described. Methanocorpusculum strains are weakly motile and form irregularly coccoid cells, about 1 μm in diameter. The cell envelope consists of a cytoplasmic membrane and a S-layer, composed of hexagonally arranged glycoprotein subunits with molecular weights of 90000 (Methanocorpusculum parvum), 92000 (M. sinense), and 94000 (M. bavaricum). The center-to-center spacings are 14.3 nm, 15.8 nm and 16.0 nm, respectively. Optimal growth of strains is obtained in the mesophilic temperature range and at a pH around 7. Methane is produced from H₂/CO₂, formate, 2-propanol/CO₂ and 2-butanol/CO₂ by M. parvum and M. bavaricum, whereas M. sinense can only utilize H₂/CO₂ and formate. Growth of M. sinense and M. bavaricum is dependent on the presence of clarified rumen fluid. The G+C content of the DNA of the three strains is ranging from 47.7–53.6 mol% as determined by different methods. A similar, but distinct polar lipid pattern indicates a close relationship between the three Methanocorpusculum species. The polyamine patterns of M. parvum, M. sinense and M. bavaricum are similar, but distinct from those of other methanogens and are characterized by a high concentration of the otherwise rare 1,3-diaminopropane. Quantitative comparison of the antigenic fingerprint of members of Methanocorpusculum revealed no antigenic relationship with any one of the reference methanogens tested. On the basis of the distant phylogenetic position of M. parvum and the data presented in this paper a new family, the Methanocorpusculaceae fam. nov., is defined.     

Elliptochloris bilobata,gen. et spec. nov., der Phycobiont vonCatolechia wahlenbergii

The phycobiont ofCatolechia wahlenbergii belongs to a new genus of theChlorococcales. It has mostly ellipsoidal, more rarely spherical cells with one bilobate through-shaped chloroplast and in general alveolar cytoplasm. Reproduction occurs by 2 or 4 autospores as well as by 16 or 32 motionless, small rodlike spores, which are formed and released in the same way as zoospores. They are aplanospores, and their formation apparently is fixed genetically, and not modificatorily, as in other species.

     

Dinitrogen and nitrous oxide produced by denitrification and nitrification in soil with and without barley plants

Summary To examine the effect of barley roots on denitrification, a pot experiment was designed to compare N₂O production and denitrification in soils with and without barley plants. Denitrification, N₂O resulting from denitrification and nitrification, and respiration were estimated by incubating pots with soil with and without intact plants in plastic bags at high moisture levels. C₂H₂-inhibition of nitrous oxide reductase (partial pressure of 10 kPa C₂H₂) was used to determine total denitrification rates while incubations with ambient air and with C₂H₂ at partial pressures of 2.5–5 Pa were used to estimate the amounts of N₂O released from autotrophic nitrification and from denitrification processes. Other sources of N₂O were presumed to be negligible. Potential denitrification, nitrification and root biomass were measured in subsamples collected from four soil depths. A positive correlation was found between denitrification rates and root biomass. N₂ was the predominant denitrification product found close to roots; N₂O formed by non autotrophic nitrifiers, assumed to be denitrifiers originated in soil not affected by growing roots. Apparently, roots promote denitrification because they consumed oxygen, thereby increasing the anaerobic volume of the soil. The ratio of actual to potential denitrification rates increased over time, especially in the presence of roots.     

Extent of intracellular pH changes during H+ extrusion by maize root-tip cells

³¹P-Nuclear-magnetic-resonance spectra of maize (Zea mays L.) root tips, that had been induced to extrude large amounts of H⁺ in response to fusicoccin (FC) in the presence of potassium salts, indicate that the cytoplasmic pH does not become higher than that of controls. In fact, the cytoplasmic pH may become slightly (approx. 0.1 pH unit) lower in cells extruding H⁺. Estimations of the buffer capacity of the cells show that without active intracellular pH regulation, H⁺ extrusion caused by FC would cause the intracellular pH to rise by at least 0.6 pH unit h^-1. Our results indicate that intracellular pH is tightly regulated even during extreme rates of acid extrusion, and that a rise in cytoplasmic pH is not the signal linking H⁺ extrusion with enhanced organic-acid synthesis or other intracellular responses to H⁺ pumping.Abbreviations FC fusicoccin - P_i inorganic phosphate - NMR nuclear magnetic resonance - chemical shift - MDP methylene diphosphonic acid     

Bathycamptus eckmani gen. et spec. nov. (Copepoda,Harpacticoida) with a review of the taxonomic status of certain other deepwater harpacticoids

Bathycamptus eckmani gen. et spec. nov., which is associated with mudballs produced by the. cirratulid Tharyx luticastellus, is described from bathyal muds in San Diego Trough, off California. ?Heteropsyllus minutus Wells from the Haden Ground, Scotland is considered to be its closest relative and is placed in the same genus. The genera Bathycamptus and Psammocamptus Mielke are regarded as sister groups on the basis of the shared sexual dimorphism shown by P3-P4. Relationships with other marine Canthocamptidae are discussed, and a re-evaluation of the genus Hemimesochra Sars is made. It is concluded that this genus should encompass only the type species H. clavularis Sars. ?Leimia dubia Wells and H. nympha Por are transferred to the new genus Boreolimella, which is closely related to Bathycamptus but not to Leimia Willey. The genus Perucamptus gen. nov. is established to include H. rapiens Becker and shows no clear relationship with the other genera. H. trisetosa Coull is assigned to Caroliiaicola gen. nov., which is regarded as being an advanced member of the Paranannopidae. H. secunda Wells is recognised as belonging to Mesopsyllus Por; whilst H. nixe Por is considered the type species of a new genus Pusillargillus.     

Oxygen consumption and ammonia excretion in the detritivore caddisfly Limnephillus sp. exposed to low pH & aluminum

Respiration and excretion were measured relative to pH and aluminum in three nymphal weight groups of a detritivore caddisfly. Although a reduction in respiration rates was consistently observed within all stages exposed to a pH of 4 and 0.3 mg 1⁻¹ of aluminum, the differencewas not statistically significant among treatments. Excretion rates, on the other hand, were significantly increased throughout the low pH treatment, but not when exposed to low pH and aluminum combined. The derived O:N ratios indicate low pH causes a shift to a protein-oriented metabolism which was most pronounced in the smallest size group. Aluminum mitigates this effect.     

Four novel yeasts from decaying organic matter: Blastobotrys robertii sp. nov., Candida cretensis sp. nov., Candida scorzettiae sp. nov. and Candida vadensis sp. nov

Four novel yeast species are described, two from decaying mushrooms, viz. Candida cretensis and Candida vadensis, and two from rotten wood, viz. Blastobotrys robertii and Candida scorzettiae. Accession numbers for the CBS and ARS Culture Collections, and GenBank accession numbers for the D1/D2 domains of the large subunit of ribosomal DNA are: B. robertii CBS 10106^T, NRRL Y-27775, DQ839395; C. cretensis CBS 9453^T, NRRL Y-27777, AY4998861 and DQ839393; C. scorzettiae CBS 10107^T, NRRL Y-27665, DQ839394; C. vadensis CBS 9454^T, NRRL Y-27778, AY498863 and DQ839396. The GenBank accession number for the ITS region of C. cretensis is AY498862 and that for C. vadensis is AY498864. C. cretensis was the only species of the four that displayed fermentative activity. All four type strains grew on n-hexadecane. C. scorzettiae is the only one of the new species that assimilates some phenolic compounds, viz. 3-hydroxy derivatives of benzoic, phenylacetic and cinnamic acids, but not the corresponding 4-hydroxy acids. This is indicative of an operative gentisate pathway.     

Transesterification of divinyladipate with glucose at various temperatures by an alkaline protease of Streptomyces sp.

The transesterification of 1 M divinyladipate with 0.25 M glucose in dimethylformamide (DMF) catalyzed by 5 mg ml^–1 alkaline protease (24 units mg^–1 min^–1) from Streptomyces sp. gave 6-O-vinyladipoyl d-glucose as the main product with yields are between 60 and 90%. The optimum temperature for the reaction was about 50 °C.     

Improved production of an enzyme that hydrolyses raw yam starch by Penicillium sp. S-22 using fed-batch fermentation

A newly isolated strain, Penicillium sp. S-22, was used to produce an enzyme that hydrolyses raw yam starch [raw yam starch digesting enzyme (RYSDE)]. The enzyme activity and overall enzyme productivity were respectively 16 U/ml and 0.19 U/ml h in the batch culture. The enzyme activity increased to 85 U/ml by feeding of partially hydrolyzed raw yam starch. When a mixture containing partially hydrolyzed raw yam starch and peptone was fed by a pH-stat strategy, the enzyme activity reached 366 U/ml, 23-fold of that obtained in the batch culture, and the overall productivity reached 3.4 U/ml h, which was 18-fold of that in the batch culture.     

松萝内生酿酒酵母菌株耐酸生理特性与分子机制探究

【目的】对我国西藏地区来源的不同酵母菌株进行有机酸发酵性能测试,此外,对具有良好产酸性能的分离自松萝内部的酿酒酵母菌株Saccharomy cescerevisiae 2-2进行耐酸性能分析,并探究其耐酸较强的分子机制。【方法】比较不同糖浓度培养基液体发酵培养过程中pH的变化,并比较低pH胁迫条件下菌株的生长,检测酿酒酵母菌株的产酸潜力和耐酸特性;对菌株2-2和模式酵母菌株S288C进行比较基因组分析,并利用实时荧光定量聚合酶链式反应(real-time fluorescence quantitative polymerase chain reaction,RT-qPCR)分析关键基因的转录,探究菌株2-2耐酸分子机制。【结果】松萝内生酿酒酵母2-2在所有检测的菌株中产酸潜力较大,耐酸性能较好。在菌株2-2中与胁迫耐受性相关的基因PDR15、PDR12和SUR1在低pH胁迫条件下存在显著的上调或下调,但这些基因转录变化趋势与菌株S288C相反。【结论】松萝内生酿酒酵母2-2是一株产酸耐酸性能较好的菌株,对其独特的调节机制进行深入分析,有希望选育性能更好的产酸酵母菌株。     

Secondary carotenoids formation by the green alga Chlorococcum sp.

The effects of temperature, pH and oxygen level onsecondary carotenoids (SC) accumulation in Chlorococcum sp. were investigated. The optimaltemperature, pH and oxygen level for the yields ofsecondary carotenoids and astaxanthin were35 ^°C, pH 8 and 10% (v/v), respectively. Whilethe ratio (R) of products containing hydroxyl group(s) to those containing keto group (s) increased withthe increase of temperature and pH, R value decreasedwith the level of oxygen. These results indicate thathigher temperature and pH favor the introduction ofhydroxyl group to the corresponding substrates,however, under high oxygen level keto group wasrelatively easy to be added compared to the additionof hydroxyl.     

A microbial fuel cell operating at low pH using the acidophile Acidiphilium cryptum

For the first time, a microbial fuel cell has been developed using an acidophile, Acidiphilium cryptum, as the anode biocatalyst. Electricity production using its natural electron acceptor, iron, as the electron mediating agent at pH values < or =4.0 was demonstrated. Accumulation of Fe(III) at the electrode, however, restricted current output. The combination of nitrilotriacetic acid and Phenosafranin as electron mediators increased the power output to 12.7 mW/m(2) in a two-chamber air-sparged fuel cell. Direct electron transfer from the microorganisms to the anode was also investigated but was not detected under the conditions studied.     

Rhodospirillum salexigens,spec. nov., an obligatory halophilic phototrophic bacterium

The name Rhodospirillum salexigens, spec. nov., was proposed for the strain WS 68, isolated by W. R. Sistrom at the Oregon coast from salt water. The spiral-shaped phototrophically or chemotrophically growing, salt demanding bacterium contains intracytoplasmic membranes arranged parallel to the cytoplasmic membrane. Bacteriochlorophyll a and spirilloxanthin are the major pigments. Growth occurs between 20 and 45°C at a neutral pH. The DNA base composition was 64 mol % guanine plus cytosine. The cell wall contains peptidoglycan and proteins but no glycolipids.     

Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium

The use of Rhizobium inoculant for groundnut is a common practice in India. Also, co-inoculation of Rhizobium with other plant growth-promoting bacteria received considerable attention in legume growth promotion. Hence, in the present study we investigated effects of co-inoculating the sulfur (S)-oxidizing bacterial strains with Rhizobium, a strain that had no S-oxidizing potential in groundnut. Chemolithotrophic S-oxidizing bacterial isolates from different sources by enrichment isolation technique included three autotrophic (LCH, SWA5 and SWA4) and one heterotrophic (SGA6) strains. All the four isolates decreased the pH of the growth medium through oxidation of elemental S to sulfuric acid. Characterization revealed that these isolates tentatively placed into the genus Thiobacillus. Clay-based pellet formulation (2.5 x 10(7) cf ug(-1) pellet) of the Thiobacillus strains were developed and their efficiency to promote plant growth was tested in groundnut under pot culture and field conditions with S-deficit soil. Experiments in pot culture yielded promising results on groundnut increasing the plant biomass, nodule number and dry weight, and pod yield. Co-inoculation of Thiobacillus sp. strain LCH (applied at 60 kg ha(-1)) with Rhizobium under field condition recorded significantly higher nodule number, nodule dry weight and plant biomass 136.9 plant(-1), 740.0mg plant(-1) and 15.0 g plant(-1), respectively, on 80 days after sowing and enhanced the pod yield by 18%. Also inoculation of S-oxidizing bacteria increased the soil available S from 7.4 to 8.43 kg ha(-1). These results suggest that inoculation of S-oxidizing bacteria along with rhizobia results in synergistic interactions promoting the yield and oil content of groundnut, in S-deficit soils.     

Acetate-mediated pH-stat fed-batch cultivation of transconjugant <Emphasis Type="Italic">Enterobacter</Emphasis> sp. BL-2S over-expressing <Emphasis Type="Italic">glmS</Emphasis> gene for excretive production of microbial polyglucosamine PGB-1

A unique cationic polyglucosamine biopolymer PGB-1 comprising more than 95% D-glucosamine was excretively produced from a new bacterial strain Enterobacter sp. BL-2 under acetate-mediated culture conditions. Since the biopolymer PGB-1 could be synthesized from the UDP-N-acetylglucosamine monomer derived from the hexosamine pathway, three glmS, glmM, and glmU genes in the hexosamine pathway were cloned from Enterobacter sp. BL-2, and their molecular structures were elucidated. The cloned glmS, glmM, and glmU genes were reintroduced into the parent strain Enterobacter sp. BL-2 through a conjugative transformation for the overproduction of the biopolymer PGB-1. The biopolymer production increased 1.5-fold in the transconjugant Enterobacter sp. BL-2S over-expressing the first-step glmS gene encoding glucosamine-6-phosphate synthase. The transconjugant Enterobacter sp. BL-2S was cultivated pH-stat fed-batch widely, while intermittently feeding an acetate solution to maintain a constant pH level of 8.0 for 72 h, resulting in 1.15 g/L of the extracellular polyglucosamine biopolymer PGB-1.     

Asterochloris phycobiontica,gen. et spec., nov., der Phycobiont der FlechteVaricellaria carneonivea

Varicellaria carneonivea is lichenized withAsterochloris phycobiontica, a new member of theChlorococcales. In the free-living state this species reproduces by zoo- and aplanospores; autospores are lacking. Sporangia develop an internal local thickening of the wall, which marks the later aperture. A group of dictyosomes apparently contributes to the formation of this thickening. Secondary carotenoids dissolved in droplets or irregular masses of oil are deposited around and within the pyrenoid.

     

Microbial Metabolism of Quinoline by Comamonas sp.

An aerobic bacterial strain which can use quinoline as the sole carbon and energy source has been isolated from activated sludge and identified as Comamonas sp. The microbial metabolism of quinoline by this strain has been investigated. A pH 8 and a temperature of 30 °C were the optimum degradation conditions of quinoline. Five intermediates including 2-oxo-1,2-dihydroquinoline, 5-hydroxy-6-(2-carboxyethenyl)-1H-2-pyridone, 6-hydroxy-2-oxo-1,2-dihydroquinoline, 5,6-dihydroxy-2-oxo-1,2-dihydroquinoline, and 8-hydroxy-2-oxo-1,2-dihydroquinoline were found during quinoline biodegradation. The presence of these intermediates suggested that at least two pathways were involved for quinoline degradation by Comamonas sp. and a reasonable degradation route was proposed to account for the intermediates observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Candida alocasiicola sp. nov., Candida hainanensis sp. nov., Candida heveicola sp. nov. and Candida musiphila sp. nov., novel anamorphic, ascomycetous yeast species isolated from plants

In a taxonomic study on the ascomycetous yeasts isolated from plant materials collected in tropical forests in Yunnan and Hainan Provinces, southern China, four strains isolated from tree sap (YJ2E(T)) and flowers (YF9E(T), YWZH3C(T) and YYF2A(T)) were revealed to represent four undescribed yeast species. Molecular phylogenetic analysis based on the large subunit (26S) rRNA gene D1/D2 domain sequences showed that strain YJ2E(T) was located in a clade together with Candida haemulonii and C. pseudohaemulonii. Strain YF9E(T) was most closely related to C. azyma and strain YWZH3C(T) to C. sorbophila and C. spandovensis. Strain YYF2A(T) was clustered in a clade containing small-spored Metschnikowia species and related anamorphic Candida species. The new strains differed from their closely related described species by more than 10% mismatches in the D1/D2 domain. No sexual states were observed for the four strains on various sporulation media. The new species are therefore assigned to the genus Candida and described as Candida alocasiicola sp. nov. (type strain, YF9E(T) = AS 2.3484(T) = CBS 10702(T)), Candida hainanensis sp. nov. (type strain, YYF2A(T) = AS 2.3478(T) = CBS 10696(T)), Candida heveicola sp. nov. (type strain, YJ2E(T) = AS 2.3483(T) = CBS 10701(T)) and Candida musiphila sp. nov. (type strain, YWZH3C(T) = AS 2.3479(T) = CBS 10697(T)).