The structural-functional organization of thermotolerant complexes of actinomycetes in desert and volcanic soils

It has been found that the number of thermotolerant actinomycetes in strongly heated soils of deserts and volcanic regions is comparable to or exceeds the number of mesophilic actinomycetes. Among the latter group, streptomyces usually predominate; among thermotolerant actinomycetes, representatives of the Micromonospora, Streptosporangium, Actinomadura, Saccharopolyspora, Microtetraspora, and Microbispora genera are identified. Thermotolerant actinomycetes display the full cycle of their development in these soils. The method of fluorescent in situ hybridization has made it possible to determine that mycelial forms predominate among the metabolically active representatives of Actinobacteria; their portion increases with the rise in the temperature of soil incubation.     

Moderately haloalkaliphilic actinomycetes in salt-affected soils

It was found that the population density of actinomycetes in solonchaks and saline desert soils varied from hundreds to tens of thousands of colony-forming units (CFUs) per 1 g of soil depending on soil type and was by 1–3 orders of magnitude lower than the number of mycelial bacteria in main soil types. Actinomycetes grow actively in saline soils, and the length of their mycelium reaches 140 m per 1 g of soil. Domination of moderately halophilic, alkaliphilic, and haloalkaliphilic actinomycetes, which grow well under 5% NaCl and pH 8–9, is a specific feature of actinomycetal complexes in saline soils. Representatives of Streptomyces and Micromonospora genera were found among the haloalkaliphilic actinomycetes. Micromonospores demonstrated lower (than streptomycetes) adaptability to high salt concentrations. Investigation of the phylogenetic position of isolated dominant haloalkaliphilic strains of streptomycetes performed on the basis of sequencing of the gene 16S rRNA enabled identifying these strains as Streptomyces pluricolorescens and S. prunicolor.     

Psychrotolerant actinomycetes in soils of the tundra and northern taiga

Actinomycetes adapted to low-temperature conditions are present in the cold soils of the tundra and northern taiga in quantities comparable to mesophylic forms and dominate in the soil actinomycete complex. Actinomycetes isolated from cold soils were identified as Streptomyces. Most actinomycetes relate to psychrotolerant forms according to habitation temperature. Two of them are conditionally psychrophilic. Specific properties of the investigated populations were identified by multirespirometrical testing.     

Aerobic and microaerophilic actinomycetes of typical agropeat and peat soils

A high number (from tens of thousands to millions of CFU/g of soil) of actinomycetes and a high diversity of genera were found in typical peat and agropeat soils. Agricultural use increases the number and diversity of the actinomycete complexes of the peat soils. In the peat soils, the actinomycete complex is represented by eight genera: Streptomyces, Micromonospora, Streptosporangium, Actinomadura, Microbispora, Saccharopolyspora, Saccharomonospora, and Microtetraspora. A considerable share of sporangial forms in the actinomycete complex of the peat soils not characteristic of the zonal soils was revealed. The number of actinomycetes that develop under aerobic conditions is smaller by 10–100 times than that of aerobic forms in the peat soils. Among the soil actinomycetes of the genera Streptomyces, Micromonospora, Streptosporangium, Actinomadura, Microbispora, and Microtetraspora, the microaerophilic forms were found; among the Saccharopolyspora and Saccharomonospora, no microaerophilic representatives were revealed.     

Psychrotolerant actinomycetes of plants and organic horizons in tundra and taiga soils

It has been revealed that in organic horizons and plants of the tundra and taiga ecosystems under low temperatures, actinomycetal complexes form. The population density of psychrotolerant actinomycetes in organic horizons and plants reaches tens and hundreds of thousands CFU/g of substrate or soil, and decreases in the sequence litters > plants > soils > undecomposed plant remains > moss growths. The mycelium length of psychrotolerant actinomycetes reaches 220 m/g of substrate. Application of the FISH method has demonstrated that metabolically active psychrotolerant bacteria of the phylum Actinobacteria constitute 30% of all metabolically active psychrotolerant representatives of the Bacterià domain of the prokaryotic microbial community of soils and plants. Psychrotolerant actinomycetes in tundra and taiga ecosystems possess antimicrobial properties.     

Neutral sugars in melanins synthesized by actinomycetes from Brazilian soils

 Nine actinomycete melanins synthesized under various culture conditions, eight of them by actinomycete samples isolated from Brazilian topsoils under savanna (cerrado) vegetation and one from an ATCC sample, were subjected to a two-step hydrolysis procedure and the sugars released qualitatively and quantitatively determined by capillary gas-liquid chromatography (GLC). Humic acids (HAs) extracted from these soils, analysed previously, were used for comparison. The neutral sugars glucose, galactose, mannose, xylose, arabinose, ribose, rhamnose and fucose and the alcohol sugar inositol were present in varying amounts in most of the melanins analysed. The same sugars were present in the HAs used for comparison, except for ribose. Some qualitative and quantitative differences observed in the two types of macromolecules would be expected, considering their origins. The results indicate that the actinomycete melanins have a qualitative sugar distribution pattern similar to that of the HAs from Brazilian tropical soils and of HAs reported for soils from other climatic regions. The possible participation of actinomycete melanins in the formation of soil humic substances is discussed. Received: 4 April 1997     

Melanogenic actinomycetes (Streptomyces spp.) from Brazilian soils

Summary Melanogenic actinomycetes were isolated from cerrado soils. Starch agar with a neutral pH was the best medium for selecting pigment-producing colonies. A pigmentation screening test selected 52% of these as possible melanin producers. Tests on liquid (organic and inorganic) and solid (peptone and tyrosine) media, and enzymatic tests, confirmed about 90% as melanin producers, 68% as dihydroxyphenylalanine (DOPA)-melanin and 32% as possible other kinds of melanin producers. Melanin production occurred mostly with an organic N, or an inorganic N with an additional organic N source. An exception was observed with three strains, which were able to produce melanins with an entirely inorganic N source in the medium. Instability of melanin production was a common feature in many strains. Further characterization of melanins produced by actinomycetes compared with soil humic acids may clarify the possible role of melanogenic actinomycetes in soil organic matter formation.     

Clay minerals and base status of strongly acid soils

In Japan, as the climate is temperate and humid, almost all soils show acid reaction. Especially, a good many strongly acid soils were reported in the survey of reclaimed lands (1, 2). The great majority of strongly acid soils are mineral soils derived from Tertiary or Diluvial sediments.     

The solubility and plant uptake of chromium from heated soils

Abstract

The effects of heating on the solubility and plant uptake of Cr from three soils variously influenced by ultramafic parent materials were evaluated. Chromium extracted by 2 M HNO₃ and by M KCl increased with degree of serpentine influence and with temperature of ignition in air. In contrast, solubility of the element was only slightly influenced by ignition in a N₂ atmosphere. Heating enhanced the solubility of soil Cr by at least two oxidative reactions: (1) the destruction of a relatively heat‐stable, probably organic, complex with the release of Cr(III), and (2) the oxidation of free Cr(III) to Cr(VI).

Corn (Zea mays L.) grew poorly in the ignited soils, but normally in ignited and leached soils. Growth depression from ignition was related to shoot Cr levels (r² = 0.494) and is attributed to the readily absorbed and translocated chromate formed at elevated temperatures. Under more usual soil conditions, as in the untreated and ignited then leached soils, the less readily soluble forms of the element are the principal contributors to available Cr.     

Estimates of viral abundance in soils are strongly influenced by extraction and enumeration methods

Viruses are highly abundant in temperate soils, ranging from 10⁷ to 10⁹?g^?1, and outnumbering soil bacteria from 5- to over 1,000-fold. In order to determine the potential impacts of viruses on soil microbial communities, it is important to establish reliable methods for comparing changes in viral abundances within and across soil samples. The goals of this study were to optimize extraction-enumeration methods to accurately determine viral abundances in a range of soil types, to evaluate the feasibility of simultaneously enumerating bacterial cells and virus particles using a single extraction procedure, and to assess the utility of flow cytometry (FCM) for enumerating virus particles in soil extracts. Comparisons of extraction approaches indicated that sonication or blender extraction of soils with potassium citrate buffer yielded the highest viral abundances for most soil types. Combined viral and bacterial extractions underestimate abundances compared to separately-optimized extractions for each. Flow cytometric counts were anywhere between 350- and 1,400-fold higher than epifluorescence microscopy (EFM)-based counts for the same soil. Trends in viral abundance across soil types were different from those via EFM, and different relationships between viral abundance and soil properties were observed depending on the enumeration method. Thus, FCM is not currently recommended for enumeration of viruses in soil extracts. Based on EFM results, soil moisture and organic matter content were the most important factors determining viral abundance in soils.     

Ecological and taxonomic features of actinomycetes complex of the soils of the Lake Elton region

Ecological and taxonomic characteristics of the actinomycete complex of solonchak soils and light chestnut soils in the Lake Elton region have been presented. Data on the abundance and taxonomic structure have confirmed the ecological importance of actinomycetes in soils with evident signs of salinity.     

Effects of drying and wetting on extractable aluminum in strongly acid soils and in aluminum-saturated clays

A number of field-moist strongly acid soils, NaObr-treated soils, and Al-saturated clays were subjected to drying and wetting treatments in the laboratory. Oven drying of samples resulted in decreases in extractable Al and increases in extractable H from field-moist soils containing more than 12 mequiv./100 g exchange acidity and from Al-saturated clays, and wetting the samples resulted in the reverse. However, when field-moist soil samples containing less than 7 mequiv./100 g exchange acidity were oven dried, both the extractable Al and extractable H tended to increase. Removing organic matter with NaOBr from a soil sample low in exchange acidity resulted in a change from an increase to a decrease in extractable Al upon oven drying. In all cases, the extractable Al and extractable H contents fluctuated cyclically with repeated drying and wetting. The cause for the observed changes was attributed to Al hydrolysis, with additional influence from soil acidity buffering, Al interlayer formation, and inorganic and organic matter dissolution.     

Mouthpart morphology and trophic position of microarthropods from soils and mosses are strongly correlated

Mosses provide habitat for microarthropod communities that are dominated in abundance and richness by mites. Although these systems are used as experimental models to address questions of relevance to general ecology, and despite the fact that they are also of relevance to key, ecosystem-wide functions such as nutrient cycling rates, the trophic relationships that underpin these functions are poorly resolved. The complexity of the moss habitat matrix and the small size of its residents have hampered progress in the determination of diets. We use stable isotope analysis of moss communities and present tools that allow for more in-depth studies of food web structure in mosses and soils than are currently available. We test in mites for the first time the association between mouthpart morphology and isotope signatures. Isotopes capture the diet of mites under field conditions and over a longer time-span than traditional, snapshot measures of diet such as gut contents analyses. Our data suggest that cheliceral morphology can be used as a first inexpensive and quick filter for estimation of dietary preference in mites, with ambiguous trophic relationships resolved through isotope analyses. This work provides new information and tools for the study of mite-dominated food webs.     

Two routes in genesis of strongly differentiated acid soils under humid, cool-temperate conditions

When usual pedological data are combined with detailed biogeochemical and crystallochemical analyses, they indicate existence of two major evolutionary routes within the humid, cool-temperate zone.

1. (a) The first route is the direct result of acidolytic weathering of minerals under the influence of soluble organic compounds which are formed by decomposition of organic matter. This process is thus the result of induced acidification of an extrinsic character, i.e., a podzolization process.

2. (b) The second route is accomplished in a progressive manner according to a true evolutionary sequence. The geochemical mechanisms brought into play are, on the one hand, aluminization of the weathering complex as a result of the hydrolytic desaturation of clays (induced acidification) and, on the other hand, deferrification under hydromorphic conditions, i.e., a degradation process.

The fundamental distinction thus indicated between these two pedological routes serves to answer certain questions relative to genesis and classification of soils of temperate coolzones.     

酸性黄壤施用磷石膏对高粱营养生长和膜保护酶的影响

采用盆栽试验, 研究了贵州强酸性(pH 4.3)黄壤施用磷石膏对高粱生长、养分平衡、细胞膜保护酶活性的影响.结果表明, 在强酸性土壤上种植耐铝能力弱的高粱, 铝毒害明显, 即使施用足量的氮磷钾肥, 作物也生长不良.施用磷石膏和石灰后高粱出苗和生长正常, 各生物学性状均极显著优于对照, 施磷石膏高粱长势优于施石灰处理;高粱干物质量与磷石膏(X1)、石灰(X2)的施用量呈二次曲线变化(回归方程分别为: Yw=6.88+11.92X1-1.65X12, R=0.983**;Yw=6.88+6.39X2-0.72X22, R=0.996**);磷石膏降低酸性黄壤铝毒、提高植物钙含量的效果略逊于石灰, 在提高植物营养3要素(特别是磷、钾元素)的作用方面优于石灰, 施磷石膏植株磷含量是石灰处理的1.17～2.43倍;施高量磷石膏的高粱植株氮/磷、氮/钾、钾/磷比值分别为6.8～7.1、1.2～1.3和5.4～5.6, 比值适中、变幅小, 氮/铝、磷/铝、钾/铝、钙/铝比值提高, 改善和调节了高粱体内氮、磷、钾、钙养分的平衡.高粱叶片细胞膜保护酶(SOD、CAT和POD)活性分析表明, 施磷石膏、石灰后SOD和CAT活性增加, POD活性和脯氨酸含量下降, 施磷石膏效果优于石灰.     

Effect of crop residue biochar on soil acidity amelioration in strongly acidic tea garden soils

Strongly acidic soil (e.g. pH < 5.0) is detrimental to tea productivity and quality. Wheat, rice and peanut biochar produced at low temperature (max 300 °C) and differing in alkalinity content were incorporated into Xuan‐cheng (Ultisol; initial pH_{soil/water = 1/2.5} 4.12) and Ying‐tan soil (Ultisol; initial pH _{soil/water = 1/2.5} 4.75) at 10 and 20 g/kg (w/w) to quantify their liming effect and evaluate their effectiveness for acidity amelioration of tea garden soils. After a 65‐day incubation at 25 °C, biochar application significantly (P < 0.05) increased soil pH and exchangeable cations and reduced Al saturation of both tea soils. Association of H⁺ ions with biochar and decarboxylation processes was likely to be the main factor neutralizing soil acidity. Further, biochar application reduced acidity production from the N cycle. Significant (P < 0.05) increases in exchangeable cations and reductions in exchangeable acidity and Al saturation were observed as the rate of biochar increased, but there were no further effects on soil pH. The lack of change in soil pH at the higher biochar rate may be due to the displacement of exchangeable acidity and the high buffering capacity of biochar, thereby retarding a further liming effect. Hence, a significant linear correlation between reduced exchangeable acidity and alkalinity balance was found in biochar‐amended soils (P < 0.05). Low‐temperature biochar of crop residues is suggested as a potential amendment to ameliorate acidic tea garden soils.     

Gibbsite and halloysite decomposition in strongly acid podzolic soils developed from granitic saprolite of the Bayerischer Wald

The present study reports the occurrence of gibbsite and halloysite in soils derived from granitic saprolites and from glacial deposits formed from granitic saprolites of the Bayerischer Wald (Germany). Both minerals are common in soils of this area. They were formed in the initial stages of weathering, most probably before the Pleistocene and in a warmer climate. Under present conditions halloysite and gibbsite are unstable in the surface soils, as indicated by a decrease in gibbsite concentration towards the surface and by an undersaturation of the equilibrium soil solution with respect to both minerals. It is assumed that the strongly acid conditions and the high concentration of organic compounds in the surface horizons lead to dissolution of gibbsite and possibly to transformation of halloysite to kaolinite.     

Studies on the ecology of actinomycetes in soil II. The pH requirements of streptomycetes from two acid soils

The streptomycetes in the horizons of two pine forest soils were enumerated and isolated using neutral and acidified media. The pH requirements of all species isolated were tested in culture and two distinct groups, neutrophiles and acidophiles, were recognized. Growth of representative species at different pH in liquid medium and sterile soil was studied and found to be similar. The significance of the existence of both acidophilic and neutrophilic species in acid soils was discussed. It was suggested that acidophilic actinomycetes may be more widespread and important in soil than has been thought previously.     

Microbial biomass and nitrogen transformations in surface soils strongly acidified by volcanic hydrogen sulfide deposition in Osorezan, Japan

Volcanic acidification has created unique ecosystems that have had to adapt to the acidic environments in volcanic regions. To characterize the primary microbial properties of strongly acidified soils in such environments, we investigated microbial biomass, nitrogen transformations and other relevant chemical properties in the surface soils of solfatara and forests from Osorezan, a typical volcanic region in Japan, and compared the results to common Japanese forest soils. Soil microbial biomass C (MBC) and N (MBN) were determined using the chloroform fumigation–extraction method. Potential net N mineralization and net nitrification were measured in aerobic laboratory incubations. Long-term acidification in the Osorezan soils by volcanic hydrogen sulfide deposition caused low soil pH (3.0–3.8), base cation deficiency and increased concentrations of toxic ions such as Al³⁺. The proportions of MBC to total carbon (MBC/TC ratio) and MBN to total nitrogen (MBN/TN ratio) were lower than those in common Japanese forest soils. The extreme acidic conditions may have inhibited microbial survival in the Osorezan acid soils. Net N mineralization occurred at rates comparable to those in common Cryptomeria japonica forest soils, probably because of the presence of acid-tolerant soil microorganisms. Net nitrification was completely inhibited and autotrophic ammonia oxidizers were not detected by the MPN method. The inhibition of nitrification prevents nitrogen leaching from the soils, thus maintaining a nitrogen cycle in the volcanic acid region in which     (and NH₃) is recycled among microorganisms and plants.