The interactive effects of soil transplant into colder regions and cropping on soil microbiology and biogeochemistry

Soil transplant into warmer regions has been shown to alter soil microbiology. In contrast, little is known about the effects of soil transplant into colder regions, albeit that climate cooling has solicited attention in recent years. To address this question, we transplanted bare fallow soil over large transects from southern China (subtropical climate zone) to central (warm temperate climate zone) and northern China (cold temperate climate zone). After an adaptation period of 4 years, soil nitrogen components, microbial biomass and community structures were altered. However, the effects of soil transplant on microbial communities were dampened by maize cropping, unveiling a negative interaction between cropping and transplant. Further statistical analyses with Canonical correspondence analysis and Mantel tests unveiled annual average temperature, relative humidity, aboveground biomass, soil pH and NH₄⁺‐N content as environmental attributes closely correlated with microbial functional structures. In addition, average abundances of amoA‐AOA (ammonia‐oxidizing archaea) and amoA‐AOB (ammonia‐oxidizing bacteria) genes were significantly (P < 0.05) correlated with soil nitrification capacity, hence both AOA and AOB contributed to the soil functional process of nitrification. These results suggested that the soil nitrogen cycle was intimately linked with microbial community structure, and both were subjected to disturbance by soil transplant to colder regions and plant cropping.     

The divalent cation requirement of Dead Sea halobacteria

Pleomorphic Halobacterium strains isolated from the Dead Sea (H. volcanii, H. marismortui) require high concentrations of divalent cations (75 mM Mg²⁺) for growth. When suspended in medium containing less than 50 mM Mg²⁺ cells lose their native shape within minutes and become spherical. This occurs even at elevated sodium chloride concentrations. Concomitant with the morphological changes, a high mlecular weight component which is positive in Coomassie Brilliant Blue and in periodate Schiff stain is released into the surrounding medium. At divalent cation concentrations lower than 100 mM magnesium cells were shown to lose their viability and their ability to incorporate amino acids. The potency of different divalent cations or their combinations to enable growth and stabilize morphology and viability was studied. It is suggested that different mechanisms underlie the divalent cation requirement of the different functions.     

Occurrence of virus-like particles in the Dead Sea

Electron-microscopic examination of water samples from the hypersaline Dead Sea showed the presence of high numbers of virus-like particles. Between 0.9 and 7.3 × 10⁷ virus-like particles ml⁻¹ were enumerated in October 1994 in the upper 20 m of the water column during the decline of a bloom of halophilic Archaea. Virus-like particles outnumbered bacteria by a factor of 0.9–9.5 (average 4.4). A variety of viral morphologies were detected, the most often encountered being spindle-shaped, followed by polyhedral and tailed phages. In addition, other types of particles were frequently found, such as unidentified algal scales, and virus-sized star-shaped particles. Water samples collected during 1995 contained low numbers of both bacteria and virus-like particles (1.9–2.6 × 10⁶ and 0.8–4.6 × 10⁷ ml⁻¹ in April 1995), with viral numbers sharply declining afterwards (less than 10⁴ ml⁻¹ in November 1995–January 1996). It is suggested that viruses may play a major role in the decline of halophilic archaeal communities in the Dead Sea, an environment in which protozoa and other predators are absent. Received: February 5, 1997 / Accepted: May 24, 1997     

Aquatic entomofauna of a Dead Sea oasis

A survey of the aquatic and semi-aquatic insect fauna of a semi-tropical, arid zone oasis on the western Dead Sea coast, was conducted primarily in the summer and winter seasons of 1980/81. A table is given of the aquatic entomofauna, including their zoogeographical affinities, Israeli distribution and presence in En Gedi and in each of the two canyons there. Zoogeographical analysis reveals a predominance of tropical and arid African affinity (Ethiopian = 31%, Saharo-Arabian = 19%), with a major affinity also to the Mediterranean (21%). The entomofaunal community was divided among seven ecological biotopes: fast or slow flowing streams and pools; eddies; bedrock or deep pools; standing or stagnant pools. A community analysis table of the occurrence of the major faunal elements in each of seven biotopes is presented. Some rather stenotopic taxa were indicative of biotopes. A comparison is made of summer and winter seasonality including the effects of flash floods and the relation of these phenomena to emigration/imigration and life cycles of the entomofauna. The effects of agriculture and tourism are discussed and proposals made for conservation of the biotope communities. These biotopes and their entomofaunal communities are presumed to represent most of the habitats of Middle East arid zone springs.     

Density of Monoporeia affinis and biogeochemistry in Baltic Sea sediments

This study focused on effects from Monoporeia affinis reworking and ventilation activities on benthic fluxes and mineralization processes during a simulated bloom event. The importance of M. affinis density for benthic solute (O₂, ΣNO₂⁻ + NO₃⁻, NH₄⁺ and HPO₄²⁻) fluxes and sediment reactivity (mobilization of NH₄⁺ and HPO₄²⁻) following additions of organic material to the sediment surface was experimentally investigated using sediment-water and closed sediment (jar) incubations. Three different densities of M. affinis were used to resemble a low, medium and high density situation (1300, 2500 and 6400 ind. m^− 2, respectively) of a natural amphipod community. The degradation of phytodetritus (Tetraselmis sp., 5 g C m^− 2) added to the sediment surface was followed over a period of 20 days. Benthic solute fluxes of O₂, ΣNO₂⁻ + NO₃⁻ and NH₄⁺ were generally progressively stimulated with increasing number of M. affinis, while no such correlation was found for HPO₄²⁻. Solute fluxes were initially enhanced 1 to 2 days after the addition of phytodetritius, caused by mineralization of the most labile organic material and a food-stimulated irrigation by the amphipods. There was no effect from the activity of M. affinis on total denitrification (Dtot = Dn + Dw) or denitrification utilizing nitrate from coupled nitrification/denitrification (Dn) for any of the densities examined. Denitrification utilizing overlying water nitrate (Dw) was only about 10% of Dtot. Dw was significantly enhanced for the highest M. affinis density investigated. The reactivity of the sediment decreased progressively with increasing density of M. affinis and with time of the experiment. However, enhanced ammonium production at least 6 days after the organic addition indicated excretion of N-containing organic compounds by M. affinis. In conclusion, large spatial and temporal variations in density of M. affinis may be of significant importance for benthic solute fluxes and overall mineralization of organic material in Baltic Sea sediments.     

菌物:死海不死（英文）

东非裂谷北端的死海位于以色列和约旦之间。它代表了我们这个星球上最深的洼地,在众多的水体中,它的盐度最高,高达33%。如今,在死海南部的盐被用于工业回收。约旦河是死海的主要水源。由于农业和工业大量使用死海的水,以及自然蒸发,其水位每年减少约1 m。自古以来死海一直以其治疗的功能而闻名,近年来死海已成为一个旅游圣地(马察达,谷木兰)。"死海"的名字意味着不适宜居住和致命的地方。到目前为止,只有较低等的微生物(细菌、真菌、藻类)在死海中生存。为了找到更高级的生物,如丝状真菌,一个国际研究小组(以色列、乌克兰、德国)共同对死海中的高级真菌进行分离鉴定;在不同的水质类型、矿化度和孵化温度条件下,在琼脂培养皿中测试其生长特性、酶活性和染料的降解作用(自我清除活性的指示反应)。总之,作为假设,许多不同分类系统和生态群丝状真菌的菌株都已被鉴定,并针对其生长特性、酶活性和染料降解能力进行研究。正如题目所言:死海不死!由此,《旧约》称之为"盐海",不是"死海",所以,我们可以确信的说:"圣经毕竟是正确的"。     

Bacteriorhodopsin in a bloom of halobacteria in the Dead Sea

A dense bloom of red halobacteria developed in the Dead Sea in the summer 1980, bacterial densities of up to 1.9 x10⁷ cells ml^-1 were observed. The population consisted of two types: pleomorphic, cup-shaped cells and rod-shaped cells. A high content of bacteriorhodopsin was found in the bloom (up to 0.4 nmol per mg protein). The rod-shaped Halobacterium was isolated and was shown to contain bacteriorhodopsin.Abbreviations 20 specific gravity at 20°C - Tris Tris-(hydroxymethyl)-aminomethane     

The Dead Sea — an economic resource for 10 000 years

The archaeological and historical record of the Dead Sea as an economic resource is longer than that of any other hypersaline lake. Although it is completely devoid of life, except for a few bacteria and algae, the climatic and geological conditions in the Dead Sea basin have produced circumstances which made this lake important for the economy of the area. The salt which was produced by evaporation of the water, or by quarrying from the salt diapir of Mt. Sodom, on the Dead Sea coast, is referred to in the Bible and in the Talmud. It was harvested until the 1930's. Potash has been extracted from the brine, by solar processes, since 1931 and today the Dead Sea is a major source of potash and bromine. The asphalt, which is found in seepages along the shores and in large blocks, occasionally found floating on the lake, has been used by the inhabitants of the area for waterproofing baskets and for decorative purpose, since the Pre-ceramic Neolithic Period, 10 000 years ago. Later, the asphalt became a major export item to Egypt. During the Early Bronze age, 4000 years ago, it was used mostly to glue flint implements to wooden handles and in the Graeco-Roman period it was used as one of the components in the embalming of Egyptian mummies. The area around the Dead Sea was the only source of balsam, perhaps the most important incense and medication of the Ancient World. Remains of a 7th century B.C. perfume factory, were found in Ein Gedi. During later periods, until the Arab conquest in the 7th century A.D., the growing of balsam was an imperial monopoly. The area of the Dead Sea was famous, for over 2000 years, for its dates and sugar. The therapeutical and medicinal properties of Dead Sea water and the hypersaline hot springs on its shore, were famous throughout the Ancient World. For example, King Herod the Great, 2000 years ago, used to visit the area to cure his many diseases. This practice continues today, and the lakes has become a major center for treatment of psoriasis. There is pictorial, archaeological and historical evidence to support the Dead Sea's importance as a trade artery for over 2300 years.     

Heavy metals in the Dead Sea and their coprecipitation with halite

After a prolongued period of stratification (about 300 years) the Dead Sea overturned in 1979 and again in 1982. Its waters became saturated with respect to halite and the massive precipitation of halite which occurred in winter 1982/83 has been monitored. We followed the fate of the heavy metals during this period of physical and chemical changes.The concentrations of Zn, Cd, Pb and Cu in the Dead Sea waters have been measured by anodic stripping voltammetry (ASV) which provided sensitive measurement of these elements after a minimal pretreatment of the samples (dilution 1: 1 and acidification). In the meromictic lake (prior to 1979), the concentrations of all four elements were larger in the deep anoxic layers. With the onset of halite precipitation a decline in their concentrations was observed. Most dramatic was the decrease in Cd, which practically disappeared from the water column in 1985. The coprecipitation of heavy metals with halite — collected by sediment traps in 1983 — was examined, as well as that of older halite recovered from a sediment core. Although concentrations of heavy metals were somewhat larger in recent halite, all halite samples had the same coprecipitation pattern: the concentration of Pb was the largest, followed by Cd, and that of Cu was the smallest. The apparent distribution coefficient was larger for Cd than for Pb.We estimated the amount of Cd which may have accompanied the deposition of halite during 1983–1985; it is compatible with its observed disappearance from the water column in 1985. The amounts of Pb and of Zn which are missing from the Dead Sea of 1985 are much larger than can be accounted for by coprecipitation with halite. A possible explanation is that the formation of halite crystals may have enhanced settling of particulates which in turn, may have scavenged Pb and Zn from the Dead Sea waters. Cu seems to be much less affected by the physical and chemical events which occurred in the Dead Sea during 1976–1985.     

Subsurface microbiology and biogeochemistry of a deep, cold-water carbonate mound from the Porcupine Seabight (IODP Expedition 307)

The Porcupine Seabight Challenger Mound is the first carbonate mound to be drilled (∼270 m) and analyzed in detail microbiologically and biogeochemically. Two mound sites and a non-mound Reference site were analyzed with a range of molecular techniques [catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), quantitative PCR (16S rRNA and functional genes, dsrA and mcrA ), and 16S rRNA gene PCR-DGGE] to assess prokaryotic diversity, and this was compared with the distribution of total and culturable cell counts, radiotracer activity measurements and geochemistry. There was a significant and active prokaryotic community both within and beneath the carbonate mound. Although total cell numbers at certain depths were lower than the global average for other subseafloor sediments and prokaryotic activities were relatively low (iron and sulfate reduction, acetate oxidation, methanogenesis) they were significantly enhanced compared with the Reference site. In addition, there was some stimulation of prokaryotic activity in the deepest sediments (Miocene, > 10 Ma) including potential for anaerobic oxidation of methane activity below the mound base. Both Bacteria and Archaea were present, with neither dominant, and these were related to sequences commonly found in other subseafloor sediments. With an estimate of some 1600 mounds in the Porcupine Basin alone, carbonate mounds may represent a significant prokaryotic subseafloor habitat.     

Dynamics of a bloom of halophilic archaea in the Dead Sea

After a period of more than ten years in which bacterial and algal community sizes were extremely small, a dense bloom of halophilic archaea developed in the upper 5–10 m of the Dead Sea water column in the summer of 1992. The development of this bloom followed a dilution of the upper water layer by winter rainfloods, which enabled the development of a short-lived dense bloom of the unicellular green alga Dunaliella parva. The dense archaeal community (up to 3.5 × 10⁷ cells m1^–1 in June 1992) imparted a red coloration to the Dead Sea, due to its high content of bacterioruberin. Bacteriorhodopsin was not detected. High levels of potential heterotrophic activity were associated with the bloom, as measured by the incorporation of labeled organic substrates. After the decline of the algal bloom, archaeal numbers in the lake decreased only little, and most of the community was still present at the end of 1993. The amount of carotenoid pigment per cell, however, decreased 2–3-fold between June 1992 and August 1993. No new algal and archaeal blooms developed after the winter floods of 1992–1993, in spite of the fact that salinity values in the surface layer were sufficiently low to support a new algal bloom. A remnant of the 1992 Dunaliella bloom maintained itself at the lower end of the pycnocline at depths between 7 and 13 m (September 1992–August 1993). Its photosynthetic activity was small, and very little stimulation of archaeal growth and activity was associated with this algal community.     

Dead Sea water trajectories in the T–S space

The Dead Sea water column is composed, to a first approximation, of two water bodies: the deep waters, constituting most of the lake's volume, and a shallow upper layer a few meters thick. The temperature and salinity profiles can both be either stabilizing or destabilizing, depending on the regime and the season; if salinity is destabilizing, and double-diffusive processes are attained, the two water bodies mix at a much faster rate than normal turbulent diffusion can account for. The trajectories of the Dead Sea brines since 1977 belong to one of three different categories: upper layer under a meromictic regime, upper layer under a holomictic regime, and lower layer under a holomictic regime. The lower layer during the meromictic regime of 1979– 82 remained constant in its properties and its trajectory is thus represented by one single point. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nutrients in pore waters from Dead Sea sediments

Pore waters were separated from 50 cm-long cores of Dead Sea sediments raised from waters depths of 25, 30 and 318 m. The salinity of the pore water is close to that of the overlying water at 225–230 g l^–1 chloride. The titration alkalinity of the pore water is about 60 % of the overlying water, and sulfate is also depleted. Ammonia and phosphate concentrations are higher than those of the water column with up to 50 mg l^–1 N-NH₃ (ten times increase) and 350 µg l^–1 P-PO _inf4 ^sup3– (four to eight times increase). Early diagenetic reactions are a result of decomposition of organic matter and of water-sediment interactions, resulting in aragonite precipitation, phosphate removal to the sediments, probably by absorption on iron-oxyhydroxides followed by remobilization, reduction of sulfate and formation of iron sulfides and accumulation of ammonia. Mass balance calculations show that pore water contribute about 80% of the ammonia and 30% of the phosphate input into the Dead Sea water column. On the other hand, the sediments act as a sink for carbonate and sulfate.     

A First Record of Obligate Halophilic Aspergilli from the Dead Sea

The isolation of obligate halophilic aspergilli from the Dead Sea and the range of salt tolerance of halophilic fungi isolated, are reported here for the first time. The mycobiota of the Dead Sea isolated in this study, was dominated by Aspergillus and Penicillium species; Cladosporium were found in lesser numbers. All three genera were obtained from the water sample; however, Aspergillus was the only genus obtained from the sediment. There was significant difference in growth of each isolate at different salt concentrations and intraspecies analysis revealed dissimilarity in response of strains to different salt concentrations in the growth medium The isolates were euryhaline, with halotolerance up to 20–25% solar salt, Aspergillus and Penicillium species showing a higher level of halotolerance, as compared to that of Cladosporium. Halophilic fungi were found in greater numbers in the sediment sample as compared to that in the water sample. Penicillium and Cladosporium species were exclusively facultative halophiles, while some species of Aspergillus were facultative halophiles. All the obligate halophiles isolated, belonged to the genus Aspergillus and were identified as A. penicillioides and A unguis, the latter being a first record of the species from the Dead Sea.     

Survival of Filamentous Fungi in Hypersaline Dead Sea Water

A variety of filamentous fungi have recently been isolated from the Dead Sea (340 g/L total dissolved salts). To assess the extent to which such fungi can survive for prolonged periods in Dead Sea water, we examined the survival of both spores and mycelia in undiluted Dead Sea water and in Dead Sea water diluted to different degrees with distilled water. Mycelia of Aspergillus versicolor and Chaetomium globosum strains isolated from the Dead Sea remained viable for up to 8 weeks in undiluted Dead Sea water. Four Dead Sea isolates (A. versicolor, Eurotium herbariorum, Gymnascella marismortui, and C. globosum) retained their viability in Dead Sea water diluted to 80% during the 12 weeks of the experiment. Mycelia of all species survived for the full term of the experiment in Dead Sea water diluted to 50% and 10% of its original salinity. Comparison of the survival of Dead Sea species and closely related isolates obtained from other locations showed prolonged viability of the strains obtained from the Dead Sea. Spores of isolates obtained from the terrestrial shore of the Dead Sea generally proved less tolerant to suspension in undiluted Dead Sea water than spores of species isolated from the water column. Spores of the species isolated from the control sites had lost their viability in undiluted Dead Sea water within 12 weeks. However, with the exception of Emericella spores, which showed poor survival, a substantial fraction of the spores of Dead Sea fungal isolates remained viable for that period. The difference in survival rate between spores and mycelia of isolates of the same species points to the existence of adapted halotolerant and/or halophilic fungi in the Dead Sea.